This document provides readers with an understanding of how to use WAI-ARIA 1.1 [[WAI-ARIA]] to create accessible rich internet applications. It describes considerations that might not be evident to most authors from the WAI-ARIA specification alone and recommends approaches to make widgets, navigation, and behaviors accessible using WAI-ARIA roles, states, and properties. This document is directed primarily to Web application developers, but the guidance is also useful for user agent and assistive technology developers.

This document is part of the WAI-ARIA suite described in the WAI-ARIA Overview.

Introduction

This section is informative.

The WAI-ARIA Authoring Practices Guide is intended to provide an understanding of how to use WAI-ARIA to create an accessible Rich Internet Application. It describes recommended WAI-ARIA usage patterns and provides an introduction to the concepts behind them.

This guide is one part of a suite of resources that support the WAI-ARIA specification. The WAI-ARIA suite fills accessibility gaps identified by the [[WAI-ARIA-ROADMAP]].

As explained in Background on WAI-ARIA, languages used to create rich and dynamic web sites, e.g., HTML, Javascript, CSS, and SVG, do not natively include all the features required to make sites usable by people who use assistive technologies (AT) or who rely on keyboard navigation. The W3C Web Accessibility Initiative's (WAI) Protocols and Formats working group (PFWG) is addressing these deficiencies through several W3C standards efforts, with a focus on the WAI-ARIA specifications. For an introduction to WAI-ARIA, see the Accessible Rich Internet Applications Suite (WAI-ARIA) Overview.

With the understanding many prefer to learn from examples, the guide begins with a section that demonstrates how to make common widgets accessible with descriptions of expected behaviors supported by working code. Where it is helpful to do so, the examples refer to detailed explainations of supporting concepts in subsequent sections. The sections that follow the examples first provide background that helps build understanding of how WAI-ARIA works and how it fits into the larger web technoloby picture. Next, the guide covers general steps for building an accessible widget using WAI-ARIA, JavaScript, and CSS, including detailed guidance on how to make rich internet applications keyboard accessible. The scope then widens to include the full application, addressing the page layout and structural semantics critical to enabling a usable experience with assistive technologies on pages containing both rich applications and rich documents. It includes guidance on dynamic document management, use of WAI-ARIA Form properties, and the creation of WAI-ARIA-enabled alerts and dialogs.

Design Patterns and Widgets

This section demonstrates how to make common rich internet application widgets and patterns accessible by applying WAI-ARIA roles, states, and properties and implementing keyboard support.

Although users of Mac OS X are familiar with using the Command key instead of the Control key, the Command key is typically reserved for desktop applications and OS-level integration. Until device and platform independence can be addressed in WAI-ARIA 2.0, the primary Control modifier key for WAI-ARIA widget interaction is specified as Control on all platforms, including Mac OS X.

Generally Applicable Keyboard Recommendations

The following keyboard conventions are applicable to many of the patterns described in subsequent sections.

The following guidance on nested widgets will be moved to another section.

Widgets within Widgets The general navigation model is for a user to tab to a widget, interact with the controls in that widget and then tab to move focus to the next widget in the tab order. By extension, when the construct of a widget contains another widget, tab will move focus to the contained widget because it is the next item in the tab order. This continues down the layers of widgets until the last widget is reached. For example, if there are two widgets A and B on a page where widget A contains within it Widget A1 and Widget A1 contains within it Widget A2, the focus sequence when pressing the tab key would be A1, A2, A3, B.

Accordion

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

An accordion component is a collection of expandable panels associated with a common outer container. Panels consist of a header and an associated content region or panel. The primary use of an Accordion is to present multiple sections of content on a single page without scrolling, where all of the sections are peers in the application or object hierarchy. The general look is similar to a tree where each root tree node is an expandable accordion header. The user navigates and makes the contents of each panel visible (or not) by interacting with the Accordion Header. Terms for understanding accordions include:

accordion component:
Collection of panels within a common outer pane.
accordion header:
Label area of an accordion panel. This is where you find the control to expand or collapse the panels.
accordion panel:
Contents area associated with an accordion header.
Keyboard Interaction:
  • Tab - When focus is on an accordion header, pressing the Tab key moves focus in the following manner:
    1. If interactive glyphs or menus are present in the accordion header, focus moves to each in order.
    2. When the corresponding panel is expanded (its aria-expanded state is 'true'), then focus moves to the first focusable element in the panel.
    3. If the panel is collapsed (its aria-expanded state is 'false' or missing), OR, when the last interactive element of a panel is reached, the next Tab key press moves focus as follows:
      • If a subsequent accordion panel is already expanded, focus moves to the first focusable element in this subsequent panel.
      • If no subsequent accordion panel is expanded, focus moves to the first focusable element outside the accordion component.
  • Left arrow
    • When focus is on the accordion header, a press of up/left arrow keys moves focus to the previous logical accordion header.
    • When focus reaches the first header, further up/left arrow key presses optionally wrap to the first header.
  • Right arrow
    • When focus is on the accordion header, a press of down/right moves focus to the next logical accordion header.
    • When focus reaches the last header, further down/right arrow key presses optionally wrap to the first header
  • Up arrow - behaves the same as left arrow
  • Down arrow - behaves the same as right arrow
  • Control+Up arrow - Moves focus from anywhere in the accordion content to its associated accordion header or tab respectively.
  • Control+PageUp -
    • When focus is inside of an accordion pane, pressing Control+PageUp moves focus to the accordion header of the previous accordion pane.
    • When focus is in the first accordion header content, pressing Control+PageUp optionally moves focus to the last accordion header.
    • Focus will simply move to the header and will require Enter/Space to expand/collapse the accordion pane.
  • Control+PageDown -
    • When focus is inside of an accordion pane, pressing Control+PageDown moves focus to the header of the accordion pane.
    • When focus is in the last accordion header content, pressing Control+PageDown optionally moves focus to the first accordion header.
    • In the case of an accordion, focus simply moves to the header and requires Enter/Space to expand/collapse the accordion pane.
  • End - When focus is on the accordion header, an End key press moves focus to the last accordion header.
  • Home - When focus is on the accordion header, a Home key press moves focus to the first accordion header.
  • Enter/Space - When focus is on an accordion header, pressing Enter/Space toggles the expansion of the corresponding panel.
    • If collapsed, the panel is expanded, and its aria-expanded state is set to 'true'.
    • If expanded, the panel is collapsed and its aria-expanded state is set to 'false'.
  • Shift+Tab - Generally the reverse of Tab.
  • Alt+Delete -
    • When deletion is allowed, with focus anywhere within the tab panel or tab, pressing Alt+Delete will delete the current tab and tab panel from the tabbed interface control. If additional tabs remain in the tabbed interface, focus goes to the next tab in the tab list. If no additional tabs remain, then focus moves to the last place that held focus in the previous tab panel.
    • An alternative to providing a keystroke to close a tab is to provide a context menu that is associated with the tab title. When focus is on the tab, pressing Shift-F10 or pressing the right mouse button will open a context menu with the close choice.
    • A warning should be given to the user before allowing the delete to occur.

In Firefox, pressing Control+PageUp / Control+PageDown moves between browser tabs. Firefox also supports Control+Tab and Control+Shift+Tab to move between tabs. Internet Explorer 7 also uses Control+Tab and Control+Shift+Tab. There may be advantages to using Control+PageUp/PageDown as the keys to change tabs because it is a recognizable keystroke to at least Firefox users and it is also supported by the Windows operating system to move between panels in a tabbed dialog.

You should be aware of two issues with using Control+PageUp/PageDown:

  • The first arises when the user is within a tabbed interface control on a Web page. Here they can not easily switch browser tabs without first moving focus outside of the tabbed interface control. This may be acceptable.
  • The second arises when the entire web page is a tabbed interface control. In this case the user could not switch browser tabs unless the control on the web page ignored the Control+PageUp/PageDown keypress (and thus letting the browser access it) when the first or last tab was reached.
WAI-ARIA Roles, States, and Properties:
  • The accordion component must have a role of tablist and have aria-multiselectable="true" This will enable an assistive technology, such as screen reader, to convey that the tablist is an accordion or a multiselectable tablist. This will also tell the user that the keyboard navigation matches an accordion and not a tablist.
  • Contained within the tablist is a set of tab/tabpanel pairs.
  • Each header tab in the tablist has a role of tab.
  • The accordion panel uses the role tabpanel and should have an aria-labelledby relationship referencing the correponding header having a role of tab
  • The tabpanel is considered a grouping for all content consisting of that tabpanel.
  • An accordion should manage the expanded/collapsed state of each tab by maintain its aria-expanded state.
  • An accordion should manage the selected state of each tab by maintaining its aria-selected state.
  • An accordion should convey the visibility of each tabpanel by maintaining its aria-hidden state.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Open Ajax Alliance Accordion

Alert

Characteristics:
Description:

An alert is an element that displays a brief, important message in a way that attracts the user's attention without interrupting the user's task. Dynamically rendered alerts are automatically announced by most screen readers, and in some operating systems, they may trigger an alert sound. It is important to note that, at this time, screen readers do not inform users of alerts that are present on the page before page load completes.

Because an alert is intended to provide important and potentially time-sensitive information without interfering with the user's ability to continue working, authors should ensure alerts do not affect the keyboard focus. If there is a need to interrupt work flow, consider using an alert dialog

In most circumstances, authors should avoid making alerts disappear automatically. An alert that disappears too quickly can lead to failure to meet WCAG 2.0 success criterion 2.2.3. In addition, authors should be careful to avoid overuse of alerts. Frequent interruptions inhibit usability for people with visual and cognitive disabilities, leading to failures to meet WCAG 2.0 success criterion 2.2.4.
Keyboard Interaction:

An alert (WAI-ARIA live region) does not require any keyboard interaction.
WAI-ARIA Roles, States, and Properties:

The widget has a role of alert.

Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Open Ajax Alliance

Alert Dialog or Message Dialog

This section has had only minor edits since it was integrated from APG version 1.0 -- a complete APG taskforce review is pending.

Characteristics:
Description:

A dialog with the primary purpose of communicating a message and acquiring a user response to that message. Examples include action confirmation prompts, warning messages, or help for an invalid form entry. The dialog should be modal. Keyboard focus is set on an element in the dialog. The element that has initial focus will depend on the nature of the information conveyed in the dialog. Simple message dialogs, as described below, have their initial focus set to the confirmation button (e.g., the OK button). Detail message dialogs have their initial focus set on the element containing the message.

A detail message dialog conveys a message that has any one of the following attributes:

  • Is more than one sentence in length;
  • Contains information where punctuation is an essential part of the message, such as syntax of a required date format;
  • Contains detail information the user may need to re-use, e.g., a phone number, e-mail address, error number, etc.;
  • Contains an interactive element, such as a link to a help resource.

If the dialog is not a detail message dialog, one can consider it a simple message dialog.
Keyboard Interaction:

See Dialog (Modal).

  • Content authors make alert dialogs modal by ensuring that, while the alertdialog is shown, keyboard and mouse interactions only operate within the dialog.
  • The message area of a detail message dialog is focusable and has a document role so screen reader users will have complete access to the message content, e.g., the screen reader can read it by character, word, or line.
  • When the message area of a dialog is focusable and has focus, a visual focus indicator is required, and it is recommended that the indicator encompass the complete message.
WAI-ARIA Roles, States, and Properties:
  • The node containing all elements of the dialog, including the alert message and any dialog buttons, has an alertdialog role.
  • Message areas have role document and tabindex="0".
  • The Alert dialog has an aria-labelledby that references the title of the dialog. If there is not a visible title, use an appropriate aria-label instead.
  • The element with role alertdialog has an aria-describedby referring to the message element that has role document.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Open Ajax Alliance

Auto Complete

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A textbox and an associated drop-down list of choices where the choices offered are filtered based on the information typed into the box. Typically, an icon associated with the textbox triggers the display of the drop-down list of choices. An editable auto-complete accepts text entry of choices that are not in the list. An example of an editable auto-complete is the URL field in the browsers.

Keyboard Interaction:
  • With focus in an empty textbox, press Down Arrow, Up Arrow, Alt+Down Arrow, or Alt+Up Arrow to display the entire list of choices. Focus remains in the textbox and no choice is highlighted.
    • Press the Down Arrow to highlight the first choice in the list.
    • Press the Down Arrow and Up Arrow keys to highlight the desired choice in the list.
    • Note that the arrows will wrap through the textbox when the top or bottom of the list is reached. For example, pressing the down arrow when the last choice is highlighted will move focus back to the textbox, pressing down again will move focus to the first item in the list. Likewise, with focus in the textbox and the list displayed, pressing up arrow will move focus to the last item in the list.
    • When a choice is highlighted using the arrow keys, the highlighted choice is displayed in the textbox.
    • Press Enter to select the highlighted choice and close the drop-down list. This mimics the behavior of the HTML select element.
  • With the drop-down list of choices displayed, move the mouse pointer over an item in the list to highlight it. The textbox value is not modified when the mouse is used to highlight a choice. Clicking on the highlighted choice will close the drop-down and update the textbox with the selected choice. This mimics the behavior of the HTML select element.
  • With focus in an empty textbox, type any letter. If any of the available choices begin with the letter typed, those choices are displayed in a drop down. If the letter typed does not match any of the available choices the drop-down list is not displayed.
  • With focus in textbox with an existing value type additional letters. As the user types letters the list of choices is filtered so that only those that begin with the typed letters are displayed.
    • Until the user presses the arrow keys to highlight a particular choice, only the typed letters are displayed in the textbox.
    • In an editable auto-complete, if no choices match the letter(s) typed, the drop down list closes.
    • In a non-editable auto-complete, any letters that do not result in a match from the list are ignored, the drop down list of choices remains static until the user presses Escape to clear the text field, Backspace to remove some of the letters previously typed, or types an additional letter that results in a valid list of choices.
    • Navigation through the list of choices and display of the highlighted choice in the textbox works as described above.
      Optional: When a choice is highlighted via arrow key navigation, the input cursor is left at the end of the typed entry and the highlighted choice is displayed in the textbox with the characters after the input cursor selected. Typing an additional character will remove the auto-completed portion and append the newly typed character to the end of the previously typed characters. The list will be filtered based on the additional character(s) typed.
  • With focus in a textbox, press Escape
    • If there is no text in the textbox, pressing Escape closes the drop-down if it is displayed.
    • For an editable autocomplete that has text in the textbox that was both typed by the user and auto-completed by highlighting a choice using the keyboard, the auto-completed portion of the text is cleared and the user typed characters remain in the textbox. The drop-down list is closed. To completely clear the textbox contents the user must use the backspace key to remove the typed characters. This is how the Google search box in the Firefox UI works. Recommend that pressing the Escape key again completely clears the textbox rather than relying on only the backspace key.
    • For a non-editable auto-complete that has text in the textbox that was both typed by the user and auto-completed by highlighting a choice using the keyboard, pressing Escape closes the drop-down list and leaves the current choice in the textbox.
    • For an editable or non-editable auto complete with text in the textbox that was typed by the user and the mouse is highlighting a choice in the drop down (keyboard navigation was NOT used), pressing Escape closes the drop down and leaves the typed text displayed in the text box. Need to consider if pressing Escape again should clear the typed text. The user must press the Down arrow or Alt+Down arrow or click the associated icon to invoke the drop-down list of choices again.
  • Moving focus out of an empty auto complete field where a value is required should either invoke an error or if a default value was initially assigned, reset the value to the default value.
  • Moving focus out of an auto complete field that does not contain a valid entry should either invoke an error or if a default value was initially assigned, reset the value to the default value.

It is good practice to limit the number of matching items in the drop down to a reasonable number. The reasonable number is determined by the task at hand. A list of the 50 US States is probably reasonable, but a list containing all of the office numbers in a building is probably not appropriate.

WAI-ARIA Roles, States, and Properties:
  • The widget has a role of combobox.
  • The combobox has an aria-autocomplete property set to one of 'inline', 'list', or 'both'.
  • For more information, see the combobox design pattern.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Dojo autocomplete

Button

Characteristics:
Description:

A button is a widget that enables users to trigger an action or event, such as submitting a form, opening a dialog, cancelling an action, or performing a delete operation. A common convention for informing users that a button launches a dialog is to append "…" (ellipsis) to the button label, e.g., ."Save as …".

In addition to the ordinary button widget, WAI-ARIA supports 2 other types of buttons:

  • Toggle button: A two-state button that can be either off (not pressed) or on (pressed). To tell assistive technologies that a button is a toggle button, specify a value for the attribute aria-pressed. For example, a button labeled mute in an audio player could indicate that sound is muted by setting the pressed state true. Important: the label on a toggle button should never change when the state changes. In this example, when the pressed state is true, the label should not change to "Unmute"" or "Muted."
  • Menu button: as described in the menu button pattern, a button will be revealed to assistive technologies as a menu button if it has the property aria-haspopup set true.

The types of actions performed by buttons are distinctly different from the function of a link (see link pattern). It is important that the role of a widget matches the function it provides. Ideally, the role of the element also matches its visual appearance. But, occasionally an element may be visually styled as an icon or link but perform the action of a button. In these cases, the element should be given a button role. The Designers should work to avoid conflicts between visual appearance and WAI-ARIA semantics.
Keyboard Interaction:

With focus on the button, pressing the Space key or Enter key activates the button. Focus should behave appropriately for the type of action being performed. For example:

  • If activating the button opens a dialog, the focus moves inside the dialog. (see dialog pattern)
  • If activating the button closes a dialog, typically focus should return to the button that opened the dialog unless the function performed in the dialog context logically leads to a different element. For example, activating a cancel button in a dialog should always return focus to the button that opened the dialog. However, if the dialog is confirming a delete action that deletes the page from which it was opened, the focus must logically move to a new context.
  • If activating the button does not dismiss the current context, then focus should typically remain on the button after activation, e.g., an Apply or Recalculate button.
  • If the button action indicates a context change, such as move to next step in a wizard or add another search criteria, then it may be appropriate to move focus to the starting point for that action.
  • If the button is activated with a shortcut key, the focus should usually remain in the context from which the shortcut key was activated. For example, if Alt+U were assigned to an "Up" button that moves the currently focused item in a list one position higher in the list, pressing Alt+U when the focus is in the list should not move the focus from the list.
WAI-ARIA Roles, States, and Properties:
  • The button has role of button.
  • An accessible label is required. By default, the accessible name is computed from any text content inside the button element. However, it can also be provided with aria-labelledby" or aria-label.
  • If a description of the button's function is present, the button element has aria-describedby set to the ID of the element containing the description.
  • When the action associated with a button is unavailable, the button displays in a aria-disabled state.
  • If the button is a toggle button, it has an aria-pressed state. When the button is toggled, the value of this state is true, and when not toggled, the state is false.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Checkbox

Characteristics:
Description:

WAI-ARIA supports two types of checkbox widgets:

  1. Dual-state: The most common type of checkbox, it allows the user to toggle between two choices -- checked and not checked.
  2. Tri-state: This type of checkbox supports an additional third state known as partially checked.

One common use of a tri-state checkbox can be found in software installers where a single tri-state checkbox is used to represent and control the state of an entire group of install options. And, each option in the group can be individually turned on or off with a dual state checkbox.

  • If all options in the group are checked, the overall state is represented by the tri-state checkbox displaying as checked .
  • If some of the options in the group are checked, the overall state is represented with the tri-state checkbox displaying as partially checked.
  • If none of the options in the group are checked, the overall state of the group is represented with the tri-state checkbox displaying as not checked.

The user can use the tri-state checkbox to change all options in the group with a single action:

  • Checking the overall checkbox checks all options in the group.
  • Unchecking the overall checkbox unchecks all options in the group.
  • And, In some implementations, the system may remember which options were checked the last time the overall status was partially checked. If this feature is provided, activating the overall checkbox a third time recreates that partially checked state where only some options in the group are checked.
Keyboard Interaction:

When the checkbox has focus, pressing the Space key changes the state of the checkbox.

WAI-ARIA Roles, States, and Properties:
  • The checkbox has role checkbox.
  • The checkbox has an accessible label, preferably provided by a visible label associated using aria-labelledby.
  • When checked, the checkbox element has the state aria-checked="true".
  • When not checked, it has the state aria-checked="false".
  • When partially checked, it has the state aria-checked="mixed".
  • If a set of checkboxes is presented as a logical group with a visible label, the checkboxes are included in an element with role group that has the property aria-labelledby set to the ID of the element containing the label.
  • If the presentation includes additional descriptive static text relevant to a checkbox or checkbox group, the checkbox or checkbox group has the property aria-describedby set to the ID of the element containing the description.
Examples:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Combo Box

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: A combo box enables the user to type in a field and at the same time chose a predefined value from a list. By using the keyboard the user can select an item from the list. After selection she will be able to type further characters in the field.
Keyboard Interaction:
  • Left Arrow or Right Arrow move the caret within the edit field.
  • Alt+Up/Down Arrow opens and closes the list.
  • Up Arrow and Down Arrow moves focus up and down the list. As focus moves inside the dropdown list, the edit field is updated.
  • Page Up/Page Down selects the next/previous pages item depending on the lists size.
  • Escape closes the dropdown list, returns focus to the edit field, and does not change the current selection.
  • Enter selects the current item on the list, updates the edit field, highlights the selected item in the dropdown list, closes the dropdown list, and returns focus to the input field.
  • Typing a letter (printable character) key moves focus to the next instance of a visible node whose title begins with that printable letter.

For combo boxes that implement aria-autocomplete, see the autocomplete design pattern.
WAI-ARIA Roles, States, and Properties:

A combobox can be implemented using either of two design patterns:

  1. As a combination of text field, which may be editable, a displayable list of items, and a drop button to toggle the display of that list; all wrapped in the form of a single widget with role of combobox.
  2. As a combobox, which behaves like a textfield and may be editable, with a displayable list of items, and a drop button to toggle the display of that list;

Like text fields a combobox should be labeled to convey the purpose of the widget. Keyboard focus within the widget must be managed by the widget. Comboboxes are used extensively in graphical user interfaces and the design pattern for the widget should be semantically correct.

For the first combobox design pattern:

  • The container element that wraps the combobox has a role of combobox.
  • The first element within the combobox is an input text field and is responsible for managing the keyboard focus between the text field and the list as well as displaying the list. The text field is in the tab order. If you create a text field without using a standard HTML text field form control then ensure that it is in the tab order.
  • If the text field is not editable it must have have aria-readonly = true.
  • The combobox must have aria-expanded = true if the list is displayed or aria-expanded = false when it is not.
  • The next element is an html <button>, or another element with a role of button. This element is used to toggle the display of the combobox's drop down list.
  • The next element has a listbox role and represents the drop down list. It manages keyboard navigation among list items and navigating back to the text field if necessary.
  • Each item in the listbox is an option. Options are not in the tab order.
  • Provide a label for the combobox by referencing the text field in the combobox. You can use an aria-label to associate this label with the combobox or you may use the HTML <label> element and its for attribute to reference the text field.

For the second combobox design pattern:

  • The first element for the combobox has a role of combobox and behaves like an input text field and is responsible for managing the keyboard focus between the combobox and the list as well as displaying the list. The text field is in the tab order. If you create a text field without using a standard HTML text field form control then ensure that it is in the tab order.
  • If the combobox is not editable it must have have aria-readonly = true .
  • The combobox must have aria-expanded = true if the list is displayed or aria-expanded = false when it is not.
  • The next element is an html <button>, or another element with a role of button. This element is used to toggle the display of the combobox's drop down list.
  • The next element has a listbox role and represents the drop down list. It manages keyboard navigation among list items and navigating back to the text field if necessary.
  • Each item in the listbox is an option. Options are not in the tab order.
  • Provide a label for the combobox by referencing the text field in the combobox. You can use an aria-label to associate this label with the combobox or you may use the HTML <label> element and its for attribute to reference the text field.

For each combobox pattern the button need not be in the tab order if there is an appropriate keystroke associated with the input element such that when focus is on the input, the keystroke triggers display of the associated drop down list. In this case, a Tab to focus the button is unnecessary. This is the same behavior as the select element.

Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

First design pattern -- container element with role combobox :

Second pattern -- text field with role combobox :

Date Picker

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: The DatePicker widget allows the user to select a date or date ranges. The DatePicker shows one month at least. All navigation that is described below depends on the application. If no range selection is possible, the relevant keystroke interaction can be ignored. Also navigation to the past might be optional. Each week might be labeled with the corresponding calendar week number.

As a general rule the actual calendar portion of the date picker follows a table structure where days of the week and calendar day numbers are layed out in table cells. This provides context so an assistive technology can render the day of the week; its corresponding numeric calendar day, and week number if necessary. Consequently, it is best to start with an HTML table and apply WAI-ARIA semantics for a grid. However, should the author wish to uses a div or span to represent the cells then the DOM structure for a table is duplicated with rows marked with role="row."

The calendar portion can be displayed in a numbers of ways, including as a popup associated with another widget, or as a static region of a page.

Keyboard Interaction:

Keyboard navigation on days that are not included the currently displayed month should move to the month automatically and lead to the day in the next or previous month.

  • Tab - Like other widgets, the date picker widget receives focus by tabbing into it. Once focus is received, focus is repositioned on today's date in a grid of days and weeks. A second tab will take the user out of the date picker widget. Focus initially is placed on today's date.
  • Shift+Tab - reverses the direction of the tab order. Once in the widget, a Shift+Tab will take the user to the previous focusable element in the tab order.
  • Up Arrow and Down Arrow - goes to the same day of the week in the previous or next week respectively. If the user advances past the end of the month they continue into the next or previous month as appropriate.
  • Left Arrow and Right Arrow - advances one day to the next, also in a continuum. Visually focus is moved from day to day and wraps from row to row in a grid of days and weeks.
  • Control+Page Up - Moves to the same date in the previous year.
  • Control+Page Down - Moves to the same date in the next year.
  • Space -
    • Singleton Mode: acts as a toggle either selecting or deselecting the date.
    • Contiguous Mode: Similar to selecting a range of text. Space selects the first date. Shift+Arrows add to the selection. Pressing Space again deselects the previous selections and selects the current focused date.
  • Home - Moves to the first day of the current month.
  • End - Moves to the last day of the current month.
  • Page Up - Moves to the same date in the previous month.
  • Page Down - Moves to the same date in the next month.
  • Enter -
    • If the the calendar is a popup attached to some other widget (e.g., a text field), then Enter dismisses the popup, and the selected date(s) are shown in the associated widget.
    • If the calendar is a static region on the page, then Enter confirms the selected date(s).
  • Escape - in the case of a popup date picker, closes the widget without any action.

Navigation into the past is optional

Do not implement keyboard navigation schemes that would place more than one calendar day in the tab order at any time as this impacts the usability of keyboard navigation. For example, using HTML anchors for the gridcells places them all in the tab order impacting the usability of keyboard navigation.

WAI-ARIA Roles, States, and Properties:
  • The current month has a label representing the month and year. It is advisable to use a role heading but is not essential. This "label" should have a unique ID.
  • If the author would like to ensure that a label is announced by a screen reader, as the label changes, include live region properties with the label element: aria-live="assertive" and aria-atomic="true".
  • The container for the day of week headers and numeric days of the week has a role of grid.
  • The grid has an aria-labelledby property with a value equivalent to the id of the label for the grid.
  • Each name for the day of the week has a role columnheader and is not navigable via the keyboard.
  • Each numeric day of the week has the role gridcell.
  • When a day is selected its aria-selected is set to true, otherwise it is set to false or removed.
  • Changes in aria states, identified here, as well as focus, are clearly styled to show the user where their point of regard is and what days are selected.

When the datepicker is active a calender day of the week always has focus. This can be achieved by setting the tabindex on that day as appropriate and then using script to give it focus. Alternatively, the grid container could set aria-activedescendant to the id of the currently focused gridcell. Keep in mind that older browsers may not support aria-activedescendant.

Example:

Dialog (Modal)

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A dialog is a small application window that sits above the application and is designed to interrupt the current processing of an application in order to prompt the user to enter information or require a response (dialog). A modal dialog is a dialog that takes and holds focus until the dialog is closed or submitted. A specific kind of modal dialog is the alertdialog, that is used to convey a short message to the user. See the "Alert Dialog" design pattern.
Keyboard Interaction:

Keyboard navigation within a modal dialog includes these aspects:

  • Enter If the purpose of the dialog is to gather information, the dialog should have a mechanism to submit the data gathered usually via a keyboard accessible button. The Enter key should serve as the default submit action.
  • Escape There should be a method to close the dialog without taking any action. This could be implemented via a cancel button which is keyboard accessible. It is recommended that a dialog also be cancelled by pressing the Escape key with focus on any item.
  • Tab Focus must be held within the dialog until it is cancelled or submitted. As the user presses tab to move within items in the dialog, pressing tab with focus on the last focusable item in the dialog will move focus back to the first focusable item in the dialog.
  • Shift+Tab Likewise, if the user is shift-tabbing through elements in the dialog, pressing shift-tab with focus on the first focusable item in the dialog will move focus to the last item in the dialog.

Notes:

  • If the current focus item has Escape key behavior, the press of the Escape will be handled by the current item and the user may have to press Escape an additional time to close the dialog.
  • Even if the user clicks outside of the dialog on the application which invoked the dialog, focus remains in the dialog.
  • Because the dialog is modal and the user can not interact with the invoking application while the dialog is displayed, there is no requirement to make the dialog moveable via the mouse although this behavior is recommended.
  • When the dialog is closed or cancelled focus should return to the element in the application which had focus before the dialog is invoked. This is usually the control which opened the dialog.
  • When a modal dialog opens focus goes to the first focusable item in the dialog. Determining the first focusable item must take into account elements which receive focus by default (form fields and links) as well as items which may have a tabindex attribute with a positive value. If there is no focusable item in the dialog, focus is placed on the dialog container element.
  • Authors should take care when using Enter to trigger default actions since Enter might be connected to and trigger some other user interface element, or it might trigger the focused element. Authors should ensure that Enter activates only the widget they intend.
WAI-ARIA Roles, States, and Properties:
  • Generally, a modal dialog has a role of dialog.
  • If it is a simple dialog with a message that alerts, warns, or requests confirmation (e.g., "Are you sure you want quit?"), then authors are advised to use the alertdialog role. See the "Alert Dialog" design pattern for more information.
  • The dialog box title is provided by either the aria-label or the aria-labelledby property.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Dialog (Non-Modal)

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A dialog is a small application window that sits above the application and is designed to interrupt the current processing of an application in order to prompt the user to enter information or require a response (dialog).

A non-modal dialog is one which is displayed and focusable at the same time as the application which invoked it. Also like the modal dialog, focus via the tab and shift-tab key must be maintained within the dialog. However, a non-modal dialog should have a keyboard mechanism to return focus to the application while leaving the dialog open.

Keyboard Interaction:
  • Escape cancels the dialog without taking any action
  • Enter submits any data gathered in the dialog.
  • F6 is the recommended key to move focus between the application and an open non-model dialog.

Notes:

  • The mouse user may click on either the application or the dialog to change focus between the two.
  • In a Web application the non-modal dialog is usually always displayed above the application page, rather than in a separate browser window but that is not a requirement.
  • This dialog box is dragable by the mouse user and an equivalent behavior (Drag & Drop) should be offered to the keyboard only user.
  • Authors should take care when using Enter to trigger default actions since Enter might be connected to and trigger some other user interface element, or it might trigger the focused element. Authors should ensure that Enter activates only the widget they intend.
WAI-ARIA Roles, States, and Properties:

See Dialog (Modal).
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Experimental dojo floating non-modal pane

Dialog (Tooltip)

Characteristics:
Description:

A tooltip dialog is a modal dialog that is rendered near the invoking element and visually connected via a cartoon bubble-like protrusion. It is displayed when the mouse passes over or rests on that element.
Keyboard Interaction:
  • Escape The tooltip dialog is closed by pressing the escape key when focus is within the dialog, mouse clicking on a close icon, or mouse clicking outside of the dialog onto the application.
  • Tab Focus must be held within the dialog until it is cancelled or submitted. As the user presses tab to move within items in the dialog, pressing tab with focus on the last focusable item in the dialog will move focus back to the first focusable item in the dialog.
  • Shift+Tab Likewise, if the user is shift-tabbing through elements in the dialog, pressing shift-tab with focus on the first focusable item in the dialog will move focus to the last item in the dialog.

It is modal because focus is trapped within the dialog as the user navigates via the Tab and Shift+Tab key.

Unlike a true modal dialog, the user can click outside of the dialog, however in that case the tooltip dialog is immediately closed.

A tooltip dialog can not be moved/dragged.

Other than the close and move behavior, all other behaviors of a modal dialog are implemented by the tooltip dialog.
WAI-ARIA Roles, States, and Properties:

See Dialog (Modal).
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Dojo nightly

Drag & Drop

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: A drag and drop operation can occur in contexts that support selection of objects, including single and multiple selection models. An example is a tree view. The tree is a container of objects that are potentially draggable.
Keyboard Interaction:

See Drag and Drop Support, above.
WAI-ARIA Roles, States, and Properties:
  • Draggable objects are identified using the aria-grabbed state.
    • If the aria-grabbed state is absent, or if it has the value undefined, then the object cannot partake in a drag and drop operation.
    • If aria-grabbed is false, the object is draggable, but currently not being dragged.
    • If aria-grabbed is true, the object is both draggable and currently being dragged.
  • Other objects are potential drop targets. Drop targets are identified using the aria-dropeffect property.

See Drag and Drop Support for more detail.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Grid (Simple Data Tables)

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

Unlike an HTML table, which is display only, a grid presents tabular data in rows and columns that are navigable via the keyboard, and allows for cells to be selected in the grid. The user moves focus through each data cell having a role of gridcell, through the use of arrow keys. Each column has an associated element with the role columnheader. Data cells carry the role gridcell. A grid may also contain hierarchical rows. In this case the role of the grid container should be treegrid rather than grid. This design pattern, and corresponding examples, reflect a basic two-dimensional grid without grids embedded within a gridcell.

WAI-ARIA grids are not meant to replace the full functionality of a table. Consequently, there may be instances when you need to have cells span multiple columns or rows for which WAI-ARIA does not provide semantics. This can be achieved by overlaying grid and gridcell semantics onto an HTML table to provide appropriate column and row span semantics. Authors should ensure that headers are properly marked using a native header tag or WAI-ARIA columnheader or rowheader semantics. The connection between gridcell and header can be achieved using standard HTML attribute header. In HTML, multiple column or row headers for one data cell can be identified through the use of a space separated list of header ids in the headers attribute.

If a WAI-ARIA grid is not overlayed on a table, authors should mark the rowheader, columnheader, and gridcell roles on the appropriate elements. For gridcells that span multiple columns or have multiple headers, the author should apply the aria-labelledby property to the cell to the space delimited list of corresponding row or column header element IDs. Gridcells that span multiple rows or columns should be reflected in the keyboard navigation.

If a grid contains editable data, it should have both an editable mode and a navigation mode.
Keyboard Interaction:

There are two modes of keyboard interaction, namely, navigation mode and actionable mode.

Navigation Mode (Read-Only) is the default mode, and allows quick and intuitive navigation around the grid.

  • The first Tab into the grid moves focus to the first cell of the first row.
  • The second Tab leaves the grid and moves focus to the next tabbable item on the page.
  • Subsequent Tab: Once focus has been moved inside the grid, subsequent tab presses that re-enter the grid shall return focus to the cell that last held focus.
  • Right/Left arrow keys navigate through the columns. There is no wrap at the end or beginning of columns.
  • Up/Down arrow keys navigate through the rows. There is no wrap at the first or last rows.
  • Home moves the focus to the first cell of the current row.
  • End moves the focus to the last cell in the current row.
  • Page Up moves the focus to the first cell in the current column
  • Page Down moves the focus to the last cell in the current column
  • Selecting Cells
    • Control+Space selects the current column.
    • Shift+Space selects the current row.
    • Control+A selects the entire grid.
    • Shift+Arrow selects contiguous cells.
    • Shift+F8 Allows additional cells to be added to a previous selection to accomplish non-contiguous selection.

    See Global Recommendations for information on cut, copy and paste.

  • Enter or F2 pressed while focus is on a cell containing an actionable item enters Actionable Mode (see following).
  • Optionally, alphanumeric keys pressed while focus is on an actionable item enters Actionable Mode. Focus remains on the actionable item that has focus.

Actionable Mode (Interactive) allows interaction with other objects that might be found in the grid cells such as edit fields, links, menu buttons, and so on.

  • Tab moves to the next actionable item in the grid and stays within the grid wrapping at the bottom. In this mode each tabbable object in each cell of the grid can be reached with the Tab key. If multiple tabbable items are located inside a single grid cell, Tab stops at each one. When the last tabbable item in a cell is reached the next Tab moves to the next tabbable item in the grid, wrapping at the last tabbable item in the grid.
  • Shift+Tab moves to the previous actionable (tabbable) item in the grid and stays within the grid, wrapping at the top.
  • Escape exits Actionable mode (by which the user may enter text or perform an action to complete a operation) and returns to Navigation Mode (where the user is allowed to move focus among elements). If a widget is in the current grid cell that also uses the Escape key, then it should cancel the event propagation. A subsequent press of the Escape key returns focus to the parent widget.

Option: the author may choose to enable 'auto action' on a cell in order to avoid having to press Enter or F2 a second time to activate the default behavior of the object contained in a cell. For example, if the cell contains a single link the author may want to have enter follow the link rather than just move focus to it. This auto action mode should be configurable on a per cell basis as its utility is dependent on each cell's content. For example, if the cell contains multiple links, auto action should be disabled as its behavior would be ambiguous.

Option: the author may choose to implement Enter or F2 as a toggle such that pressing these keys multiple times will enter and exit actionable mode. Opinion was divided on this point. Some thought this would be confusing while others found it intuitive.

It is recommended the developer use different styling for the selection when the grid is not focused (hint: non-active selection is often shown with a lighter background color).

WAI-ARIA Roles, States, and Properties:
  • The DOM representation of the grid should follow the HTML DOM structure, although it will be possible to use aria-owns to add a row or table cell. This is an edge case and may not be supported by assistive technologies.
  • The grid container should have a role of grid.
  • The data cells should have a role of gridcell.
  • Each row should be clearly marked using a <TR> from HTML and by using a role of row.
  • Column and row headers may be represented by a <TH> if you are using an HTML table or you may explicitly use an aria role of columnheader and rowheader respectively.
  • Whenever a gridcell is selected, set aria-selected="true".
  • Whenever a row is selected, set its role to row and its aria-selected="true" allowing an AT to quickly determine that the entire row is selected.
  • By default a grid is considered to be editable, meaning all gridcells are editable. Should you want to make a grid read-only, set aria-readonly="true" on the document element having a role="grid". This will make all grid cells read-only. To override the read-only status on an individual grid cell, set its aria-readonly property to false.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Actionable, Sortable Column Header in a Grid

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

An example of a grid whose headers are sortable in either ascending or descending order based on the name in the grid column headers.

This design pattern matches that of the grid design pattern where, specifically, the author has included use of the arrow keys to permit navigation to the row or column headers that contain a button for sorting the rows of the table. Sorting is based on the data cell contents in the column being sorted, the name in the column header, and whether the contents of the column are sorted in ascending or descending order. As the order of the cells change in the column the corresponding rows move in position with respect to that sort.
Keyboard Interaction:

Keyboard navigation is identical to grid with the exceptions that: arrow key navigation includes the headers; you are not required to enter actionable mode to toggle the sort of a row or column when on the corresponding header; and content selection does not affect the selected state of row or column headers.

Simply pressing the space bar while focus is on a row or column header toggles the ascending/descending sort of the corresponding row or column.

It is recommended the developer use different styling for the selection when the grid is not focused (hint: non-active selection is often shown with a lighter background color).

WAI-ARIA Roles, States, and Properties:
  • The same as the grid design pattern with the exception that each row or column header, signified by a role of columnheader and rowheader respectively, has an aria-sort value that reflects the current state for sort for the associated row or column. If another row or column header adjusts the sort of the grid the remaining row or column header aria-sort values must reflect their sorting impact on the grid.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Landmark Navigation

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:  
Keyboard Interaction:

 
WAI-ARIA Roles, States, and Properties:

Provide the appropriate landmark for the role attribute. See the section describing landmark use.

Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Listbox

This section has been partially revised and reviewed since it was integrated from APG version 1.0 -- a complete APG taskforce review is pending.

Characteristics:
Description:

A listbox widget allows a user to select one or more items from a list of choices or options. A listbox that allows a single option to be chosen is a single-select listbox; one that allows multiple options to be selected is a multi-select listbox.

The options in a WAI-ARIA listbox are static. That is, a listbox widget is not designed to contain a list of interactive elements, such as links, buttons, or sliders. This is because browser accessibility APIs do not support child elements contained inside the list options; they provide assistive technologies only with an accessible name, which is a plain text string, and a selection state for each option.

When a screen reader user navigates the options in a list box, each static option name is spoken by the screen reader is a single piece of information. For this reason, authors should avoid creating options with very long names that contain more information than can be easily understood when spoken as a single unit of speech. Most screen reader users will not have a simple way of re-reading through the option name by character, word, or phrase if they did not understand it. See the examples for recommended ways of designing around this limitation. (Editor's note: examples are not yet coded.)

Authors should also avoid creating a large number of consecutive options that all start with the same word or phrase. Otherwise, finding a specific option can be very time consuming for a screen reader user who must listen to the repeated word or phrase while scrolling through the list. For example, if a listbox contains a list of cities where each option includes both city name and country name, and if there are 5 or more cities from each country, it would be very difficult for a screen reader user to find a city within a country if the country name precedes the city name in each option. In most cases, it would be better to have 2 list boxes, one for country and one for city, but where that is not feasible, it would typically be better to put the city name first in each option.
Keyboard Interaction:
  • The listbox element is focusable. It is either included in the tab sequence by having tabindex of 0 or greater (see Keyboard Navigation between Widgets), or it is contained within a composite widget, such as a toolbar or grid, and is made focusable by having tabindex of -1 (see Keyboard Navigation within Widgets).
  • When a listbox receives focus, visual focus is set on an option inside the listbox. If browser focus is set to the container with role listbox then aria-activedescendant must be used to refer to the option with visual focus.
  • When a single-select listbox receives focus:
    • If none of the options are selected, the first option receives focus. Optionally, it may be automatically selected.
    • If an option is selected before the listbox receives focus, focus is set on the selected item when the listbox receives focus.
  • When a multi-select listbox receives focus:
    • If none of the options are selected, focus is set on the first option. The option should not be selected when it receives focus.
    • If one or more options are selected, focus is set on the first option in the list that is selected.
  • Up and Down move focus up and down the list. If it is a single-select listbox, the selection state moves with the focus.
  • Type-ahead is strongly recommended for all lists and essential for long lists (typically more than 5 items):
    • Type a character: focus moves to the next item with a name that starts with the typed character.
    • Type multiple characters in rapid succession: focus moves to the next item with a name that starts with the string of characters typed.
  • Shift+F10: opens the context menu for the currently focused option if a context menu is available
  • Multiple Selection: In multi-select listboxes, the author may implement either of two interaction models: one that does not require modifier keys, e.g., Shift or Control, (recommended) and one that does.
    • Selection model 1 -- modifiers not required:
      • Space: changes the selection state of the focused option .
      • Control+A (optional): selects all options in the list.
      • Shift+Down Arrow and Shift+Up Arrow (optional): move the focus and select the next or previous option.
      • Control+Shift+Home (optional): selects the option with focus and all options up to the beginning of the list.
      • Control+Shift+End (optional): selects the option with focus and all options down to the end of the list.
    • Selection model 2 (modifier keys required):
      • Shift+Down Arrow and Shift+Up Arrow: move the focus and select the next or previous option.
      • Shift+Space (optional): selects contiguous items from the last selected item to the current item.
      • Control+ Down Arrow or Control + Up Arrow: move the focus without changing the selection state.
      • Control+Space Changes the selection state of the focused option.
      • Control+Shift+Home (optional): selects the option with focus and all options up to the beginning of the list.
      • Control+Shift+End (optional): selects the option with focus and all options down to the end of the list.
      • Control+A (optional): selects all options in the list.

It is recommended the developer use different styling for the selection when the list is not focused (hint: non-active selection is often shown with a lighter background color).

WAI-ARIA Roles, States, and Properties:
  • The listbox container has a role of listbox.
  • Each entry in the listbox should have a role option and should be DOM children of listbox.
  • If is not a DOM child of listbox, then it should be referenced in the listbox by aria-owns.
  • If all items in the listbox are not DOM children of the listbox, then set their aria-setsize and aria-posinset accordingly; otherwise, this information cannot be computed for context by the user agent.
  • If the listbox is not part of another widget, then it should have a visible label referenced on the listbox by aria-labelledby.
  • Each selected list item should have aria-selected="true".
Example:

Add link to example

Media Player

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:  
Keyboard Interaction:

 
WAI-ARIA Roles, States, and Properties:  
Example:

Add link to example

Popup Help (aka Bubble Help)

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

Popup Help contains more descriptive, or actionable, help-like text and elements. It may contain, and was designed to handle, interactive elements such as a button, link, or text field. It is essentially a Popup Menu with un-necessary keystrokes turned off. The key sequence for posting Popup Help was to take advantage of F1's tie to the Help paradigm (F1 calls up application Help for example).

Keyboard Interaction:
  • Control+F1
    • Posts the Popup Help widget.
    • Input focus is placed on the first interactive element in the Popup Help.
    • Control F1 is used by IE to "Display a help dialog box". In IE7 and IE8 event.cancelBubble=true; and event.returnValue=false; will allow the re-purposing of keys used by the browser. In the case of IE6, you can not stop the bubble up of keys used by the browser, but can stop the bubble up to the OS. In the case of Firefox and other standard compliant browsers, event.stopPropagation(); and event.preventDefault(); will re-purpose the keys.
    • With the exception of Control F1 to bring up Popup Help this widget is very similar to Dialog (Modal) and/or Dialog (Non-Modal) and/or Dialog (tooltip) described elsewhere in this document.
  • Esc
    • Causes no menu action and dismisses Popup Help.
    • Input focus is returned to the element, or widget the Popup Help was invoked from.
    • Pressing Enter when input focus is on the "X" glyph acts the same as pressing Esc.
  • Tab
    • One of the following occurs:
      • Modal behavior
        • Moves input focus between elements in the Popup Help's tabbing order.
          • Input focus stays in the Popup Help until one of the following occurs:
            • Esc is pressed.
            • Enter is pressed when input focus is on an interactive widget/element.
      • Non-Modal behavior
        • Moves input focus to the next tab-able element in the tabbing order if the following applies:
          • Popup Help is posted.
          • It contains no tab navigable elements in it.
  • Shift+Tab
    • As with other keyboard conventions described here, the Shift+Tab has the effect of moving the focus up rather than down and follows the same conventions as described for the modal and non-modal Tab key above.
  • Enter
    • Activates the element in the Popup Help that has input focus, if applicable, then dismisses the popup.
      • Input focus should be placed on the appropriate element after the user presses the Enter key.
        • The appropriate place to move input focus to will not always be the parent element the Popup Help was invoked from.
      • Nothing occurs if input focus is on an element that has no associated action.
  • F6
    • In the non-modal instance, the F6 key can be used to move focus between the application and the open non-modal window. This is also the behavior described in Dialog (Non-Modal) above.
WAI-ARIA Roles, States, and Properties:

See Dialog (Modal) and/or Dialog (Non-Modal) and/or Dialog (tooltip).

Example:

Add link to example.

Radio Group

Characteristics:
Description: An option in single-select list
Keyboard Interaction:

The Tab behaviour below differs from some native browser behaviors where Shift+Tab sometimes moves to the last button in the group, if none are selected.

  • Tab key will enter the radio group.
    • When Tab or Shift+Tab into a radio group, focus goes to the selected radio button. If none is selected, focus goes to the first radio button.
    • When focus is on any radio button, Tab or Shift+Tab will exit the radio group.
  • Up Arrow and Left Arrow moves focus to the previous radio button in the group, and selects that button. If focus is on the first item, then focus wraps to last item.
  • Down Arrow and Right Arrow moves focus to the next radio button in the group, and selects that button. If focus is on the last item, then focus wraps to first item.
  • Space selects the radio button with focus and de-selects other radio buttons in the group.
WAI-ARIA Roles, States, and Properties:
  • Use a container with a role radiogroup for the set of radio buttons.
  • An individual radio button has a role of radio.
  • If selected, the radio button has the state aria-checked="true".
  • If not selected, it has the state aria-checked="false".
  • It is recommended that both the radiogroup and the radio button have a label that is visible and referenced using the aria-labelledby property.
  • Use an aria-describedby property to add additional information to the radio buttons or radiogroup.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Rich Text Editor

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: Input control that accepts free-form text as its value.
Keyboard Interaction:
  • The edit control is provided by the browser; it provides the keyboard support for navigating, adding, removing and selecting text, so that behavior is not defined by the rich internet application.
  • The browser should also provide a keyboard mechanism for navigating into and out of the edit control. Within most browsers the edit control is put into the tab order of the page and can be navigated into, out of, and through using the tab and shift-tab keys like any standard form control.
  • A rich text editor widget needs to provide a user interface for interacting with the browser provided edit control. Interaction between the user interface and editor is defined here assuming that a toolbar is used.
  • Tab and Shift+Tab - If not provided by the browser, the rich text editor widget provides a keyboard mechanism to move into and out of the edit control. Tab and shift-tab are the recommended keystrokes. The toolbar or other user interface component associated with the editor is placed in the tab order immediately before the editor. To set an attribute on text within the edit control the user sets focus into the edit control, moves the insertion point, selects text and presses shift-tab to move focus from the editor back to the toolbar. The user navigates through the toolbar (see toolbar behavior) to a desired attribute and invokes that attribute. When an attribute is invoked, that attribute is applied to the selected text in the editor and focus moves back into the editor at the previous insertion point with the selection intact.
  • Options:
    • Rather than using Shift+Tab to move focus from within the editor to the toolbar, another key combination could be used (Alt+Up arrow, Control+Shift+Letter, etc.). This would eliminate the need to put the user interface control (in this example a toolbar) into the tab order immediately before the editor component. However, there are drawbacks to using a different keystroke to navigate to the user interface:
      1. It is not as "discoverable" as relying on the standard Tab/Shift+Tab behavior;
      2. It is difficult to find key combinations which are not already captured by the browser or assistive technology.
      3. Focus could stay within the toolbar after the user invokes an attribute. The user would then have to press an additional key to move focus back into the editor. This would allow multiple attributes to be set on the current selection without having to return back to the user interface but it would add an extra key sequence after setting just a single attribute. Requiring a keystroke to move focus back into the editor would also require modifying the toolbar behavior to intercept this keystroke and to know how to set focus back to the component (the editor) that the toolbar is associated with.

Optionally, if the developer wishes to provide the ability to insert a tab into the document, it is recommended one of the following methods be used.

  • Provide indent and outdent buttons in the menu. Keyboard shortcuts to the buttons should be Control+M for indent and Control+Shift+M for outdent.
  • Provide a button in the menu to toggle the use of Tab between the two modes. If this button is used, then Control+M is recommended as a keyboard shortcut to toggle the button.

 
WAI-ARIA Roles, States, and Properties:

Authors are advised to not use ARIA for rich text editors, but to rely on native HTML markup. Current rich text editors typically use an iframe element for editable content. As a result, the editable content is implicitly mapped to a document role in accessibility APIs. If using HTML5, it is recommended that authors use the designMode or contentEditable attributes.

Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Slider

Characteristics:
Description: A slider is user input where the user selects a value from within a given range. Sliders typically have a slider thumb that when moved will change the current value within the bar or track. The thumb must be keyboard accessible.
Keyboard Interaction:
  • Right Arrow and Up Arrow increase the value of the slider.
  • Left Arrow and Down Arrow decrease the value of the slider.
  • Home and End move to the first and last values of the slider.
  • Tab into and out of the slider.
  • Page Up and Page Down optionally increment or decrement the slider by a given amount.

Focus is placed on the slider. (The visual object that the mouse user would move, also known as the thumb.)

There are cases where an author may wish up/down and home/end to move the slider thumb in the opposite direction from this note. The author can do this if they think this results in a better user experience.
WAI-ARIA Roles, States, and Properties:
  • The slider control has the role slider.
  • Sliders require the aria-valuemin, aria-valuemax, and aria-valuenow properties representing the minimum possible value of the slider, the maximum possible value, and the current value. All of these are decimal numbers. The minimum and maximum are typically fixed and do not change.
  • Sometimes the value is not user readable, such as a number for the day of the week, e.g., "1". In those cases, use the aria-valuetext property to provide a human readable string for the slider's value, e.g. "Monday".
  • It is recommended that authors provide a visible label for the slider, referencing it using aria-labelledby.
  • If the slider is vertical specify aria-orientation="vertical"
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Please note that not all examples work in all browser and version combinations. For example, note the compatibility statement.

Slider (Multi-Thumb)

Characteristics:
Description: A multi-thumb slider is a slider with multiple slider thumbs designed to change 2 or more different values for an object it controls. In most cases the user is selecting a maximum and minimum value to create a range, but in some cases the 2 (or more) values selected are completely independent.
Keyboard Interaction:

This range slider allows author to modify multiple values for an object.

  • Tab to the first slider thumb.
  • Second Tab moves to next slider thumb..
  • Third Tab moves to the next slider thumb or if there are no more, it moves to the next tab stop on the page.
  • Shift+Tab moves backwards through the tabs.
  • With focus on a thumb: Same as Slider above.
    • Right Arrow and Up Arrow increase the value of the slider. If applicable this is constrained by the value of the other thumb.
    • Left Arrow and Down Arrow decrease the value of the slider. If applicable this is constrained by the value of the other thumb.
    • Home and End move to the first and last values of the slider. If applicable this is constrained by the value of the other thumb.
    • Page Up and Page Down optionally increment or decrement the slider by a given amount. If applicable this is constrained by the value of the other thumb.

Focus is placed on one of the thumbs of the slider.

All thumbs are in the tab order.

If the current value of a slider crosses over one of the other sliders, the tab order remains the same. Example. If a high range slider is moved so that its current value is below the current value of a low range slider, the thumb will visually appear to be before the low range slider. This should not change the tab order of the slider.

There are cases where an author may wish up/down and home/end to move the slider thumb in the opposite direction from this note. The author can do this if they think this results in a better user experience.
WAI-ARIA Roles, States, and Properties:
  • Each slider control has the role slider.
  • Each slider requires the aria-valuemin, aria-valuemax, and aria-valuenow properties representing the minimum possible value of the slider, the maximum possible value, and the current value. All of these are decimal numbers. The maximum of the lower slider limits the minimum of the upper slider and vice versa.
  • Sometimes the value is not user readable, such as a number for the day of the week, e.g., "1". In those cases, use the aria-valuetext property to provide a human readable string for the slider's value, e.g. "Monday".
  • It is recommended that authors provide a visible label for the multi-thumb slider, referencing it using aria-labelledby.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Spinbutton

Characteristics:
Description:

A widget that allows users to choose a value from a set, or range, of discrete values. For example, select a number from 1 to 59 for the minute of an hour when setting an alarm.

A spin button provides ways to easily increment and decrement the value. If the range is large, it may support changing the value by both a single step and by multiple steps at once. For instance, in the alarm example, the user may be able to move by 1 minute with the arrow keys and by 10 minutes with PageUp and PageDown.

A spinbutton usually includes a text field that displays the current value and allows users to directly edit it.
Keyboard Interaction:

The associated text field generally supports standard text entry operations such as selection of characters, deletions, insertions, and caret movement using the Right Arrow and Left Arrow keys. The exception is when the spinbutton's value space is restricted and the associated script limits the characters. For example, an hour-and-minute spinner would allow only the digits 1-59, the colon ':', and the characters 'AM' and 'PM'. If the user typed any other character, it would not change the contents of the text field nor the value of the spinbutton.

  • Up Arrow increases the value.
  • Down Arrow decreases the value.
  • Home and End key move to the maximum or minimum values.
  • Optional: Page Up and Page Down increase or decrease the value in larger steps.
  • Tab key moves into and out of the widget.

Focus should remain on the edit field

WAI-ARIA Roles, States, and Properties:
  • The widget has the role spinbutton.
  • Spinbuttons support the aria-valuemin, aria-valuemax, and aria-valuenow properties representing the minimum possible value of the spinner, the maximum possible value, and the current value. All of these are decimal numbers. The minimum and maximum are typically fixed.
  • Sometimes the value is not user readable, such as a number for the day of the week, e.g., "1". In those cases, use the aria-valuetext property to provide a human readable string for the slider's value, e.g. "Monday".
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Tab Panel

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A tabbed interface component is a container for resources associated with a tab. It is a set of layered pages where only one page is displayed at a time. The general look is similar to a file folder with a "tab" that contains the title of the folder. The tabs are arranged along one of the edges of the contents but most commonly are found at the top of the page. The user navigates and makes the contents of each page visible by interacting with the title "tab" of the page. Sometimes referred to as a tab container or tab panel. Terms for understanding Tab Panels include:

tabbed interface component
a set of tabs and associated tab panels
tab panel
contents area that is associated with a tab
tab
the label/title area of the tab panel. This is where you click to activate a tab panel
tablist
the set of tabs

When the user activates a tab, the contents of the corresponding tab panel is made visible. The tab is considered "active". The tab remains active until another tab is activated. The active tab is placed into the tab order. Only the active tab should be in the tab order. A default tab is specified that is active when the tabbed interface component is initialized. A collection of tabs and their associated tab panels is a complex widget, because it performs show/hide actions as well as moving the user's point of regard around within the content.

Keyboard Interaction:
  • Tab - only the active tab is in the tab order. The user reaches the tabbed panel component by pressing the tab key until the active tab title receives focus.
  • Left Arrow - with focus on a tab, pressing the left arrow will move focus to the previous tab in the tab list and activate that tab. Pressing the left arrow when the focus is on the first tab in the tab list will move focus and activate the last tab in the list.
  • Right Arrow - with focus on a tab, pressing the right arrow will move focus to the next tab in the tab list and activate that tab. Pressing the right arrow when the focus is on the last tab in the tab list will move focus to and activate the first tab in the list.
  • Up arrow - behaves the same as left arrow in order to support vertical tabs
  • Down arrow - behaves the same as right arrow in order to support vertical tabs
  • Control+Up Arrow - with focus anywhere within the tab panel, pressing Control+Up Arrow will move focus to the tab for that panel. This is not standard behavior - is this something we want to implement? Is it necessary if we provide a mechanism to change the active tab? Similar to Control+PageUp/Control+PageDown in Firefox to switch tabs?
  • Alt+Delete - When deletion is allowed, with focus anywhere within the tab panel, pressing Alt+Delete will delete the current tab and tab panel from the tabbed interface control. If additional tabs remain in the tabbed interface, focus goes to the next tab in the tab list. An alternative to providing a keystroke to close a tab is to provide a context menu that is associated with the tab title. When focus is on the tab, pressing Shift+F10 or pressing the right mouse button will open a context menu with the close choice
  • Control+PageUp - When focus is inside of a tab panel, pressing Control+PageUp moves focus to the tab of the previous tab in the tab list and activates that tab. When focus is in the first tab panel in the tab list, pressing Control+PageUp will move focus to the last tab in the tab list and activate that tab.
  • Control+PageDown When focus is inside of a tab panel, pressing Control+PageDown moves focus to the tab of the next tab in the tab list and activates that tab. When focus is in the last tab panel in the tab list, pressing Control+PageUpwill move focus to the first tab in the tab list and activate that tab.

Regarding Control+PageUp/Control+PageDown. This is currently implemented in Firefox to move between browser tabs. Firefox also supports Control+Tab and Control+Shift+Tab to move between tabs. Internet Explorer 7 also uses Control+Tab and Control+Shift+Tab. There may be advantages to using Control+PageUp/Control+PageDown as the keys to change tabs since it is a recognizable keystroke to at least Firefox users and is also supported by the Windows operating system to move between panels in a tabbed dialog. The problem is that if the user is within a tabbed interface control on a Web page, they can not easily switch browser tabs without first moving focus outside of the tabbed interface control. This may be acceptable. The other issue is if the entire Web page is a tabbed interface control - in that case the user could not ever switch browser tabs unless the control on the Web page ignored the Control+PageUp/Control+PageDown keypress (and thus letting the browser access it) when the first or last tab was reached.

WAI-ARIA Roles, States, and Properties:
  • The tabbed interface component contains tabs and their associated content panels.
  • The content panel uses the role tabpanel.
  • An element with role tab is used as a grouping label, providing a link for selecting the tabpanel to be rendered to the user.
  • Assign the aria-controls relationship of a tab to the ID of its tabpanel.
  • Authors manage the selected state of each tab by maintaining its aria-selected state.
  • A tablist is the container role for a set of elements with the role attribute set to tab.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Tool Bar

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A toolbar is a flat non-hierarchical collection of controls that provides quick access to a subset of the functions found in the menubar/menu hierarchy. Its purpose is to reduce effort in using these functions. There should neither be too few nor too many controls within a toolbar. When creating toolbars try to limit the number of items to approximately seven, as forcing users to navigate through an excessive number of items is a usability concern. Since navigation between toolbars is accomplished using a Tab keystroke, too few controls within a toolbar also creates a usability issue as it requires numerous Tab keystrokes to navigate between toolbars.

Authors must supply an aria-label property on each toolbar when their application contains more than one toolbar. The label provides information about the purpose of each toolbar; for example, an "Edit" toolbar that contains cut, copy, paste, clear, undo, and redo controls. If the application has many toolbars, it is recommended that they be placed inside a container element with a role of group to allow for keyboard navigation to the entire collection of toolbars. It is recommended that authors provide a documented key combination that allows a user to move focus quickly to the tool bar from elsewhere within the web application, placing keyboard focus on a tool within the tool bar.

It is further recommended that authors provide access to these functions via a menubar and menus to avoid cluttering the user interface with a surplus of toolbars.
Keyboard Interaction:
  • Tab moves focus to the first enabled toolbar button.
  • A subsequent Tab moves focus out of the toolbar
  • Left Arrow and Right Arrow keys navigate to the enabled buttons in the toolbar

Direction may need to be adjusted for Right to Left languages

Recommended: provide a documented keystroke that allows users to move focus quickly to the tool bar from elsewhere within the web application, placing focus on a tool within the tool bar.

There is debate concerning the treatment of disabled toolbar buttons -- should they be focusable or not? Visually, disabled buttons are grayed-out, and typicially not placed in the navigation order. This invites an issue about how a screen reader user discovers these buttons if they are not keyboard navigable. Several ways of handling this include:

  • In software applications like Microsoft® Word, the toolbars themselves are not reachable by the keyboard user, but the features are available on one of the drop-down menus.
  • Users set a preference indicating whether they want disabled buttons focusable.
  • Disabled buttons are not focusable until they are enabled. This is the way tool bars currently work.
  • Disabled buttons are focusable, but read by the screen reader as disabled.
WAI-ARIA Roles, States, and Properties:
  • The element has the role toolbar.
  • The children of the toolbar are frequently elements with role button.
  • Other tools that are common within toolbars are comboboxes and pull-down menus.
  • It is recommended that a toolbar is labelled using aria-label.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Tooltip Widget

Characteristics:
Description: Popup that displays a description for an element when a user hovers over or focuses on that element. It should popup automatically when the user gives input focus to the widget or element with which it is associated. The tooltip widget can be dismissed by pressing the Escape key or by other methods noted below. The tooltip widget differs from the Dialog (Tooltip) in that it does not receive focus at any time.

The tooltip may appear immediately or there may be a small delay before the tooltip appears.
Keyboard Interaction:

Escape: Dismisses the Tooltip.

The trigger element to which the tooltip is attached, e.g., a link, should never actually lose input focus.

If the tooltip is invoked when the trigger element gets focus, then it should be dismissed when it no longer has focus (onBlur). If the tooltip is invoked with mouseIn, then it should be dismissed with a mouseOut.

If nested widgets use the same keys, e.g., Escape, then they should be handled in a Last In First Out (LIFO) manner. For example, an editable grid contains gridcells which contain date fields. The user invokes Actionable mode on the grid and then interacts with the Date Field to invoke the Date Picker. At this point the first press of the Escape key will close the Date Picker, the second press will exit Actionable mode and return to Navigation mode.
WAI-ARIA Roles, States, and Properties:
  • Uses the WAI-ARIA role tooltip.
  • The element that the tooltip is for references the tooltip using aria-describedby.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Tree Grid

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: A grid whose rows can be expanded and collapsed in the same manner as for a tree. A Tree Grid is a combination of a Treeview and a Table with rows that are expandable
Keyboard Interaction:

There are two modes of keyboard interaction:

  • Navigation Mode (Read-Only) is the default mode, and allows quick and intuitive navigation around the grid.
    • Tab
      • The initial tab enters the grid with focus on the first cell of the first row, often a header.
      • Once in the grid a second tab moves out of the grid to the next tab stop.
      • Once focus is established in the grid, a Tab into or a Shift+Tab into the grid will return to the cell which last had focus.
    • Left Arrow and Right Arrow keys navigate between columns. If the next cell in the row is empty, focus should not move.
    • Up Arrow and Down Arrow The down arrow moves focus to the first column of a child row, if expanded. Otherwise focus is moved to the same column in the next row. Up arrow performs the same navigation but in reverse.
    • Control+Left and Control+Right Arrows expand or collapse rows.
    • If the cell contains an editable field, the Enter key starts edit mode and the Escape key exits edit mode.
    • Selecting Cells
      • Control+Space selects the current column.
      • Shift+Space selects the current row.
      • Control+A selects the entire grid.
      • Shift+Arrow selects contiguous cells.
      • Shift+F8 Allows additional cells to be added to a previous selection to accomplish non-contiguous selection.

      See Global Recommendations for information on cut, copy and paste.

The author may choose to indent child nodes visually. This should be done with an appropriate number of spacer cells marked as presentation in order to keep the headers aligned.

If cells are used for padding or layout of the hierarchy, navigation to those presentational cells should be prevented.

  • Actionable Mode (Interactive) allows the interaction with other objects that might be found in the grid cells such as edit fields, links, etc.
    • F2 pressed anywhere inside the grid will enter Actionable Mode. Focus will not be moved.
    • Enter pressed while focus is on an actionable item will enter Actionable Mode. Focus will remain on the actionable item that has focus.
    • Optionally, alphanumeric keys pressed while focus is on an actionable item will enter Actionable Mode. Focus will remain on the actionable item that has focus.
    • Tab will move to the next actionable (tabbable) item in the grid and stay within the grid wrapping at the bottom. In this mode each tabbable object in each cell of the grid can be reached with the tab key. If multiple tabbable items are located inside a single grid cell, the tab will stop at each one. When the last tabbable item in a cell is reached the next tab will move to the next tabbable item in the grid, wrapping at the last tabbable item in the grid.
    • Shift+Tab moves to the previous actionable (tabbable) item in the grid and stays within the grid, wrapping at the top.
    • Escape exits Actionable mode (by which the user may enter text or perform an action to complete a operation) and returns to Navigation Mode (where the user is allowed to move focus among elements). If a widget is in the current grid cell that also uses the Escape key, then it should cancel the event propagation. A subsequent press of the Escape key will return focus to the parent widget.
WAI-ARIA Roles, States, and Properties:

Uses the WAI-ARIA role treegrid, and requires the child element row. By default a treegrid is considered to be editable, meaning all gridcells are editable.

  • To make a treegrid read-only, set aria-readonly="true" on the document element having a role="treegrid." This will make all gridcells read-only.
  • To override the read-only status on an individual gridcell, set its aria-readonly property to false.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

  • For a visual (not accessible) example of where padding cells have been implemented see: dojo's TreeGrid example.
  • An example where padding cells have not been used (also not accessible): Oracle's Tree Grid.

Tree View

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description:

A tree view is a component to navigate hierarchical lists. It is made up of one or more top level nodes. A node may have children or it may be an end node. Nodes with children can be expanded or collapsed - when expanded its child nodes are visible. When collapsed the children are not visible. There is generally some sort of visual indication whether a node has children and can be expanded. Any number of nodes can be expanded at a time and child nodes may contain children.

An example of a Tree View is a File Navigator where a tree view is used to navigate the directories and files on a file system. The directory nodes can be expanded and collapsed to reveal its contained subdirectories and files. Terms for understanding tree views include:

node
An item in a tree.
parent node
Node with children. It can be opened / expanded or closed / collapsed
open node
Expanded node with children; first-level children are visible.
closed node
Closed node with children; the children are not visible.
end node
Node with no children

General behavior for tree views follows:

  • On first load of the tree component, the top level node is in the tab order.
  • One and only one node of the tree component is in the tab order of the page at any time.
  • The last visited node in the tree control is retained in the tab order when the user navigates away from the tree control.
  • Nodes can be focused and/or selected. There must be visual distinction between focused and selected nodes.
  • Arrowing to an item with the keyboard or clicking on an item with the mouse will focus and select the node. Any previous selections are cleared
Keyboard Interaction:
  • Up Arrow and Down arrow keys move between visible nodes.
  • Left arrow key on an expanded node closes the node.
  • Left arrow key on a closed or end node moves focus to the node's parent.
  • Right arrow key expands a closed node, moves to the first child of an open node, or does nothing on an end node.
  • Enter key performs the default action on end nodes.
  • Typing a letter key moves focus to the next instance of a visible node whose title begins with that letter.
  • Home key moves to the top node in the tree view.
  • End key moves to the last visible node in the tree view.
  • Control+Arrow to an item with the keyboard focuses the item (but does not select it). Previous selections are maintained, provided that the Control key is not released or that some other keyboard function is not performed.
  • Control+Space with focus on an item toggles the selection of the item.
  • Shift+Up Arrow extends selection up one node.
  • Shift+Down Arrow extends selection down one node.
  • Shift+Home extends selection up to the top-most node.
  • Shift+PageDown extends selection down to the last node.
  • *(asterisk) on keypad expands all nodes.
WAI-ARIA Roles, States, and Properties: A tree view uses the WAI-ARIA role tree, where tree is a main container element. A tree can itself contain subtrees that may be collapsed and expanded; these have the role treeitem. A collection of treeitems to be expanded and collapsed are enclosed in a group. See the XHTML example in the [[WAI-ARIA]] specification.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Window Splitter

Characteristics:
Description:

Visible separator between sections of a Window that is used to modify the size of the panes.

A Window Splitter can take one of two forms, namely, fixed size and variable size.

The group recommends unique naming of the window splitter to avoid the confusion that could be created by multiple splitters located on the same window.

Keyboard Interaction:
  • Tab - Like other widgets, the tab key is used to move focus to the splitter. It should appear in the normal tab order of the page. A second tab will move focus to the next tabbable item on the page.
  • Left Arrow and Right Arrow - In the case of a vertical splitter these keys will move the splitter to the left and to the right.
  • Up Arrow and Down Arrow - In the case of a horizontal splitter these keys will move the splitter up and down.
  • Enter - If pane controlled by the splitter is not collapsed, then collapse the pane. If the pane is collapsed then restore the splitter to its previous position.
  • End Optionally moves splitter so the associated pane is the largest allowed size.
  • Home Optionally moves splitter so the associated pane is the smallest allowed size. In many cases this will collapse the pane completely.
  • F6 Optionally is recommended to rotate through the window panes.

Fixed size splitter simply omits implementation of the arrow keys.

 
WAI-ARIA Roles, States, and Properties:

Uses the WAI-ARIA role separator.

  • Most window splitters are expandable and collapsible. Ensure that the splitter's aria-expanded state is updated accordingly.
  • As there may be multiple splitters, use aria-label, aria-labelledby, or the title attribute, to label the splitter in order that an accessible name is computed by the user agent. The assistive technology can then convey to users which window splitter they are controlling.
  • Authors should set the aria-controls attribute of the element having the separator role. Its value should be the IDs of the panes whose sizes it controls. An assistive technology can then provide navigation among the panes.
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Wizard

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Characteristics:
Description: A sequence of dialogs or panels guiding the user through performing a task.
Keyboard Interaction:

A Wizard can be done in several ways. Either is valid.

  • Method 1: Like a Tool Bar
  • Method 2: Controls as Default Actions
    • Escape cancels the wizard.
    • Enter invokes the "next" action; If the last page, it invokes "finish"
  • Method 3: Hot Keys
    • Control+Alt+N next, finish
    • Control+Alt+P previous
    • Escape cancel, exit without saving
    • Control+Alt+R reset current page to default settings
    • Control+Alt+S save and exit
  • Method 4: Like a Dialog

Authors should take care when using Enter to trigger default actions since Enter might be connected to and trigger some other user interface element, or it might trigger the focused element. Authors should ensure that Enter activates only the widget they intend.

WAI-ARIA Roles, States, and Properties:  
Example:

Any examples referenced here that are hosted outside www.w3.org may have changed and may not accurately exemplify the guidance in this section. The APG taskforce is developing examples for APG version 1.1 that will be directly incorporated into the guide.

Dojo nightly

General Steps for Building an Accessible Widget with WAI-ARIA

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

At this point you should have a basic understanding of how WAI-ARIA is used to support interoperability with assistive technologies. If you are not reusing a WAI-ARIA-enabled widget library and wish to create your own the following steps will guide you through the thought process for creating an accessible widget using WAI-ARIA.

  1. Pick the widget type (role) from the WAI-ARIA taxonomy

    WAI-ARIA provides a role taxonomy ([[WAI-ARIA]], Section 3.4) constituting the most common UI component types. Choose the role type from the provided table. If your desire was to create a toolbar set the role to toolbar:

    <div role="toolbar">
  2. From the role, get the list of supported states and properties

    Once you have chosen the role of your widget, consult the [[WAI-ARIA]] for an in-depth definition for the role to find the supported states, properties, and other attributes. For example, the toolbar role definition includes:

    superclass role
    In the taxonomy the widget you selected inherits states and properties from this role. In the case of a toolbar you will see that a toolbar is a subclass of a group. This makes sense given that a toolbar is a collection of commonly used functions.
    related concept
    This is really more informative to state what other concepts are similar to this role. These may exist in different host languages outside WAI-ARIA. The keyboard model for the control should emulate that of the related concept control.
    supported states and properties
    These are unique states and properties that this widget supports and that were not inherited from its ancestors in the taxonomy. In the case of a toolbar there are no such states or properties. However, in the case of a listbox, you may choose to set the property of aria-multiselectable to true if you were to have more than one item in the listitem selected at a time. This indicates to the assistive technology that the listbox manages a collection of selectable options.
    inherited states and properties
    These are all the states and properties which are inherited from the roles's ancestors and which you may use.
    global states and properties
    These are states and properties which apply to all host language components regardless of whether a role is set or not. You may use these as well.

    Once you have chosen the states and properties that apply to your widget you must set those properties you will use to set their initial values. Note: You do not need to use all the states and properties available for your role. In our case we shall use:

    <div role="toolbar" id="customToolbar" tabindex="0" aria-activedescendant="button1"
      onkeydown="return optionKeyEvent(event);"
      onkeypress="return optionKeyEvent(event);"
      onblur="hideFocus();"
      onfocus="showFocus();"
      > 
      <img src="img/btn1.gif" title="Home" alt="Home" role="button" id="button1"
           onclick="updateText('Home was invoked');">
      <img src="img/btn2.gif" title="Refresh" alt="Refresh" role="button" id="button2"
           onclick="updateText('Refresh was invoked');">
      <img src="img/btn3.gif" title="Help" alt="Help" role="button" id="button3"
           onclick="updateText('Help was invoked');"> 
</div>

    By setting tabindex=0 on the toolbar, the toolbar will receive focus in the document order. It is necessary then to use script and the aria-activedescendant property to manage virtual focus among the buttons. The details are given in step five, below.

    Important: When embedding WAI-ARIA markup in (X) HTML, all WAI-ARIA states and properties must be preceded with the characters aria- with the exception of the role and tabindex attributes. Otherwise, the user agent will not map the WAI-ARIA information, resulting in it not being recognized by assistive technologies.

    When embedding WAI-ARIA into other host languages, tabindex does not carry over. The WAI-ARIA tabindex extensions are specific to (X)HTML to repair deficiencies in keyboard support.

  3. Establish the widget structure in the markup (parent/child)

    Assistive technologies are very dependent on the structure of widgets as well as general document structure. Structure provides context to the user. A toolbar is a collection of common functions made available to the user. Therefore, all functions you would like in the toolbar must be contained within it. This can be determined by using the [[dom]] tree structure created by the browser when parsing the host language. By using the parent child relationship of the DOM, an assistive technology can determine all the related toolbar widgets associated with the toolbar. The toolbar widgets would be DOM children of the "toolbar" container. For our purposes we will define three image buttons for cut, copy, and paste.

    <div role="toolbar" tabindex="0" aria-activedescendant="button1">
  <img src="buttoncut.png" alt="cut" id="button1">
  <img src="buttoncopy.png" alt="copy" id="button2">
  <img src="buttonpaste.png" alt="paste" id="button3">
</div>
  4. Repeat steps 1-3 for the children of the parent

    We now need to assign the roles and states for each of the children. However, we shall save the detailed navigation for step 5.

    <div role="toolbar" tabindex="0" aria-activedescendant="button1">
  <img src="buttoncut.png" alt="cut" role="button" id="button1">
  <img src="buttoncopy.png" alt="copy" role="button" id="button2">
  <img src="buttonpaste.png" alt="paste" role="button" id="button3">
</div>

    The process of setting roles and states may be a recursive procedure if the children themselves have children, such as in the case of an expandable/collapsible tree widget.

  5. Establish keyboard navigation of the widget and plan for how it will be navigated to within the document

    It is very important that your widget be keyboard accessible. In fact, there must be a keyboard equivalent for every mouse operation. Where possible you should refer to the WAI-ARIA examples in this guide for tips on how to implement keyboard navigation for your widget. If you find that an example is not provided, you should follow standard keyboard bindings for UI components such as those used for the Java Foundation Classes for Windows 95/NT.

    Commented out link to conference paper, which a) was broken, and b) we should have more canonical references than conference papers for things like this.

    For our toolbar, we have chosen to have the toolbar manage the focus for its children and through the use of the aria-activedescendant property. We have also chosen to have the toolbar receive focus based on the tab order by using tabindex. In order to use aria-activedescendant, each focusable descendant must have an assigned ID. 

     <head>
 <script>
    … 
    function optionKeyEvent(event)
      {
      var tb = event.target;
      var buttonid; 
  
      DOM_VK_ENTER = 13;
      // Partial sample code for processing arrow keys

      if (event.type == "keydown") {
         if (event.altKey) {
           return true;  // Browser should use this, the menu view doesn't need alt-modified keys
         }
         // XXX Implement circular keyboard navigation within the toolbar buttons
  
         if (event.keyCode == DOM_VK_ENTER) {
           ExecuteButtonAction(getCurrentButtonID()); // This is an author defined function
         }
         else if (event.keyCode == event.DOM_VK_RIGHT) {
           // Change the active toolbar button to the one to the right (circular) by 
           var buttonid = getNextButtonID();   // This is an author defined function
           tb.setAttribute("aria-activedescendant", buttonid); 
         }
         else if (event.keyCode == event.DOM_VK_LEFT) {
            // Change the active toolbar button to the one to the left (circular) by 
            var buttonid = getPrevButtonID();  // This is an author defined function
            tb.setAttribute("aria-activedescendant", buttonid); 
         } 
         else {
            return true;
         }
         return false;
      }
      else if (event.type == "keypress") {
        …
      }
    }  
</script>

<div role="toolbar" tabindex="0" aria-activedescendant="button1" id="tb1" 
  onkeydown="return optionKeyEvent(event);"
  onkeypress="return optionKeyEvent(event);">
  <img src="buttoncut.png" alt="cut" role="button" id="button1">
  <img src="buttoncopy.png" alt="copy" role="button" id="button2">
  <img src="buttonpaste.png" alt="paste" role="button" id="button3">
</div>

    The details of implementing keyboard navigation are described in Keyboard and Structural Navigation section of this document.

    You must also show the visual focus for each element that has focus.

  6. Apply and manage needed WAI-ARIA states in response to user input events

    Similar to the processing of aria-activedescendant in Step 5, as author you must set any additional WAI-ARIA states and properties on document elements.

  7. Synchronize the visual UI with accessibility states and properties for supporting user agents

    Thomas comment: is confusing that the example switches from toolbar to treeitem. Maybe the best overall sample is to do a tree because it demonstrates each of the points you want to make?

    You should consider binding user interface changes directly to changes in WAI-ARIA states and properties, such as through the use of CSS attribute selectors. For example, the setting of the aria-selected state may change the background of a selected treeitem in a tree. This may also be done with JavaScript.

    .treeitem[role="treeitem"][aria-selected="true"] {color: white; background-color: #222222;}

.treeitem[role="treeitem"][aria-selected="false"] {color: white; background-color: beige;}

    Authors should be aware that CSS attribute selectors are not supported in some browsers, such as Internet Explorer 6. A consistent way to apply styling to reflect WAI-ARIA semantics would be to assign an element a class name based on the WAI-ARIA attribute being set using script as shown here:

    function setSelectedOption(menuItem)
     {
        if (menuItem.getAttribute("role") != "menuitem") {
           return;
        }
        var menu = getMenu(menuItem);
        var oldMenuItem = getSelectedOption(menu);
        
        // Set class so that we show selection appearance
        oldMenuItem.className="unselected";
        menu.setAttribute("aria-activedescendant", menuItem.id);
        menuItem.className= "selected";
      }
  8. Showing and Hiding Sections in a Widget

    The proper synchronization of showing and hiding sections in a widget with the WAI-ARIA display state is also critical. Some platform accessibility APIs provide events for applications to notify the assistive technology when pop-ups such as menus, alerts, and dialogs come into view or go away. Rich Internet applications can assist browsers which support these conventions by:

    1. Creating an entire section and then insert it into the [[dom]], as a subtree of the parent element activated to show the pop-up, and then removing the section from the inserted area when the pop-up goes away.

      OR

    2. Using the following style sheet properties to show and hide document sections being used to represent the pop-up items, menus or dialogs:

      • display:block
      • display:none
      • visibility:visible
      • visibility:hidden

      By monitoring these behaviors a user agent may use this information to notify assistive technology that the pop-up has occurred by generating the appropriate accessibility API event.

    Some assistive technologies may use the DOM directly to determine these when pop-up occurs. In this case, the first mechanism of writing a section to the DOM would work using the DOM events as demonstrated here. 

    	  // create new table row with table cell and div
	  var newTr = document.createElement('TR');
	  var newTd = document.createElement('TD');
	  var newDiv = document.createElement('DIV');
	  newTr.appendChild(newTd);
	  newTd.appendChild(newDiv);
	  
	  
	  //insert this new table row before the Node selected
	  var container = theNode.parentNode;
	  container.insertBefore(newTr, theNode);
	  
	  //remove theNode selected
	  container.removeChild(theNode);"

    However, if you are using CSS to show and hide sections of the DOM (2) it is essential that you set the corresponding WAI-ARIA aria-hidden property to indicate that the section is visible or hidden and synchronize it with your CSS styling as shown here: 

    [aria-hidden=true] {visibility: hidden;}

…

<div role="button" aria-haspopup="true" aria-owns="mypopupmenu">
<div role="menu" aria-hidden="true" id="mypopupmenu">…</div>
  9. Support basic accessibility, such as alternative text on images

    When an image is used to represent information within a component, such as image buttons, you need to set the alternative text on those images. This is then mapped by the user agent to the accessible name in the platform accessibility API. Using our example:

    <div role="toolbar" tabindex="0" aria-activedescendant="button1" id="tb1" 
     onkeydown="return optionKeyEvent(event);"      
     onkeypress="return optionKeyEvent(event);">    
   <img src="buttoncut" role="button" id="button1" alt="cut">
   <img src="buttoncopy" role="button" id="button2" alt="copy">
   <img src="buttonpaste" role="button" id="button3" alt="paste">      
</div>
  10. Establish WAI-ARIA relationships between this widget and others

    Once you have made the basic widget accessible you may then need to establish its relationship to other widgets. Examples of this are aria-labelledby, aria-controls, aria-describedby and aria-flowto. The details of using these relationships are described in the Relationships section of this document.

    Other relationships which should be considered are more declarative and provide context to the widget within a set. For these, aria-level, aria-posinset, and aria-setsize are provided. If you structure your Document Object Model appropriately so that the user agent can determine this information from it using the DOM hierarchy directly, you do not need to set these properties. There are, however, situations in rich internet applications where all the elements in a container are not in the DOM at one time, such as when you can only render the ten of fifty items in a subtree. In this case the user agent cannot determine the number of tree items (aria-setsize) for the position in the set (aria-posinset), and potentially the tree depth (aria-level) from the DOM. In these situations you will need to provide these WAI-ARIA properties.

  11. Review widget to ensure that you have not hard coded sizes

    The ability for applications to respond to system font settings is a requirement. Most user agents are designed to meet this requirement. This also means your Web application running within your browser is impacted when the user agent changes the font sizes to meet the need. If you have hard coded your font size in pixels an increase in system fonts will not be reflected in your Web application. You must also not hard code the size of your widgets in pixels either. If the fonts are scalable, but the widget they are encapsulated in is not, then the text could flow outside your widget.

    Follow these rules to allow your application to respond to system font settings:

    • Establish a base set of font sizes used in widgets based on percentage of the container element font size.
    • Use CSS width, borders, margin, padding, background, and positioning properties to specify the graphical rendering of widgets and their sub-components, use percentage units or em units to specify widths of widget components (An em is a the font unit of measure between the top and bottom of an upper case letter M.). Border widths, padding, and margins can use PX units.
    • Use scripting for run time CSS positioning of widget sub-components in relation to other sub components.
    • Make sure all widgets use consistent height and width units of measure.

    Percentages are the most reliable way to consistently specify proportional text sizes in widgets. The use of percentages and em should be used for specifying widths of a widget and the widget sub components. The use of percentages for text size and percentages and em units for widths support browser zoom capabilities to make widgets larger or smaller. Pixels can be used for specifying line widths, padding and margins.

    Important: Most browsers today have a zoom feature which allow the user to magnify the entire Web page. Most legislation today requires that your application respond to system font and color settings and therefore you will want to consider the fact the system settings could adversely affect your Web page should you decide to hard code pixel sizes.

  12. Compensate for Background Images when in High Contrast Mode

    Authors use background images when styling their widgets, including situations where the background image is not merely decorative, but informative. An example is a horizontal progress bar that it is filled by gradually revealing more of a background image. This is accomplished by initially setting the width of the element to zero, and then incrementing its width in accordance with the degree of progress.

    High contrast mode is an operating system display modification that makes the screen easier to see for low vision users. Some operating systems (e.g., Windows), do not display background images when in high contrast mode. Consequently, the progress bar described above appears empty regardless of the progress. It is recommended that authors not use background images as the sole method to convey important information, and to compensate with alternative or additional style rules.

    In the case of the progress bar example, a technique that works when in high contrast mode is to style the element with a border. Since the width of the element is updated as progress increases, its border gradually expands horizontally forming an ever wider unfilled rectangle. This provides alternative visual feedback as to the extent of the progress.

    Another technique is to replace a background image with text. Consider a dialog that uses a background image for its close box. To compensate for the missing close box when in high contrast mode, a lower case 'x' is used instead. The compensation technique used depends on the context, particularly the purpose of the background image.

    There are two general approaches with respect to detecting high contrast mode. They are (1) executing a script to determine if the system is in high contrast mode, or (2) providing a preference to use alternative styles. The advantage of automatic detection is that some operating systems simply apply a different color palette when in high contrast mode and do not turn off background images. In that case, authors need not compensate for missing background images. However, detection of high contrast mode by script is relatively expensive compared to a preference that users can set, and, presumably, users can see whether background images are displayed in high contrast mode on their system. It is up to individual authors to decide which method they find acceptable for their particular situation.

    The following code fragment outlines how to detect high contrast mode. 

    /* Define styles for the high contrast test element */
#hiContrastTestEl {
    border: 1px solid;
    border-color:red green;
    position: absolute;
    height: 5px;
    top: -999px;
    background-image: url('resources/blank.gif');
}
…
// An onload event handler that inserts the high contrast test element and
// then tests its computed styles.
function detectHiContrast() {
    var div = document.createElement('div');
    div.setAttribute ('id', 'hiContrastTestEl');
    // … append <div#hiContrastTestEl> to the <body> element …
    var cs = window.getComputedStyle(div);
    var bki = cs.backgroundImage;
    var hiContrast = false;
    
    // The CSS sets the top and right borders of the test element to red and
    // green, respectively.  In high contrast mode either the borders are
    // the same colour, or there is no legitimate url to the background image.
    hiContrast =    (cs.borderTopColor == cs.borderRightColor) ||
                    (bki != null && (bki == 'none' || bki == 'url (invalid-url:)'));
    
    if (hiContrast) {
        // apply hi contrast styles to compensate for missing background images.
    }
    // … remove the test element from the document …
}
  13. Test with User agent, Assistive Technology, and People with disabilities

    To ensure you have set your WAI-ARIA semantics correctly, test your application with your user agent, an assistive technology, and a person with disability. Example assistive technologies are screen readers and screen magnifiers. Ensure that your user agent is designed to support WAI-ARIA and their your assistive technology is designed to support WAI-ARIA in the selected user agent.

    Finding people with disabilities to do testing may be difficult but many companies employ people with disabilities, including your customers, and you should reach out to them to ask for help. Other places to look are advocacy groups like the National Federation of the Blind or your local schools for the blind, reading and learning centers, and so on. The people you reach out to may someday need to use what you produce.

Keyboard and Structural Navigation

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Providing an effective navigation experience to the user is critical for usability. This section starts with guidance on how to provide effective keyboard navigation for widgets in a Rich Internet Application environment. This includes a discussion on how to manage keyboard focus and the specifics on providing keyboard navigation for tooltips. This is is followed by a broader discussion on how to convey structural semantics for the entire Web page. These semantics help an assistive technology provide additional navigation, increase user productivity, and render the page in an alternative formats. This rendering may be in different forms, including but not limited to speech, page restructuring, and alternative input solutions.

Providing Keyboard Navigation for Widgets

WAI-ARIA Keyboard Bindings and Behaviors

Essential to accessible Web 2.0 widgets is keyboard support to provide full operation and functionality of a widget through keyboard-only events. Unlike traditional HTML form controls, Web 2.0 widgets, typically, have no inherent keyboard support. The developer must enable keyboard support for the widgets they create or use widget libraries with keyboard support. The model for keyboard support for Web 2.0 widgets are graphical user interface (GUI) operating systems like Microsoft Windows, Mac OS X; and other desktop operating systems like GNOME and GTK. Basic accessibility requirements for keyboard focus include:

  • Support users who cannot use pointing devices due to physical or visual impairment to access the full functionality of the Web application.
  • All major software and Web accessibility guidelines for people with disabilities require keyboard-only operation of the interface for accessibility.
  • Communicate accessibility information to assistive technologies on the type of widget and its associated state and properties.

For example, if a screen reader user hears a tree announced, they know that pressing the right arrow key will expand a node. Similarly, when they hear a grid announced, they know they can use their screen reader's table reading commands.

Keyboard Navigation between Widgets (tabindex)

The tabindex attribute enables focus to be moved via keyboard to HTML elements. For standard HTML 4.01, tabindex was limited to form and anchor elements. For WAI-ARIA, the tabindex attribute is now applicable to all renderable HTML elements with additional functionality designed to help the author produce keyboard accessible Web 2.0 widgets.

  • Tab and Shift+Tab key move focus among widgets and standard HTML controls.
  • Widgets with tabindex=0 will be added to the tab sequence based on document order
  • Widgets with tabindex>0 will be added to the tab sequence based on the TABINDEX value
  • Widgets with tabindex<0 will not be added to the tab sequence but are enabled to receive keyboard focus.

Once a widget has keyboard focus, arrow keys, Space, Enter key, or other keyboard commands can be used to navigate the options of the widget, change its state, or trigger an application function associated with the widget.

Keyboard Navigation within Widgets

Each element that receives keyboard focus needs to have a tabindex attribute set to its current active descendant element and itself if an active descendant does not exist. The element with keyboard focus is essential because it communicates information about the widget to assistive technologies like screen readers and magnifiers through operating specific accessibility APIs like Microsoft Active Accessibility (MSAA), the Apple AX APIs, and the ATK Accessibility Toolkit. The TAB key moves keyboard focus to the widget, and other keys operate the features of the widget, typically cursor keys, Enter key and Space. The actual keys are up to the developer, but best practices recommend using the same key bindings that are used to control similar widgets in common GUI operating systems like Microsoft Windows, Mac OS X and other desktop operating systems like GNOME and GTK.

Authors can use either the JavaScript focus() method to move focus to the appropriate element in the widget, or they can use a WAI-ARIA property called aria-activedescendant on the actual widget container to indicate which descendant element in the widget has focus. Use the following procedure when focus is completely dependent on the use of tabindex to provide focus in a widget:

  • Set tabindex="0" on the current active descendant in the container widget while setting tabindex="-1" on all the other descendant elements of the widget.
  • As the user navigates (e.g., arrows) away from an item, set tabindex="-1" on the old item, and tabindex="0" on the new.
  • Use the JavaScript focus() method to put focus on the new item, whose tabindex="0".

This procedure creates a roving tabindex. If the user TAB navigates away and then TABs back to the widget, the same last active descendant becomes active again. This relieves the author from having to compute and set the focus to the last active descendant.

Conversely, if you use the WAI-ARI aria-activedescendant property:

  • Set tabindex="0" on the element which is the composite widget, and set its aria-activedescendant property to the id of the descendant element you wish to be active,
  • As the user navigates (e.g., arrows) away from an item in the widget, refresh the aria-activedescendant property on the containing widget to the id of the new active descendant element.

In this scenario, the browser manages focus changes; however, the author manages changes to the aria-activedescendant property. For greater detail, see Using Tabindex to Manage Focus Among Widgets. In both scenarios authors indicate which element in the widget has focus or is active through styling and/or markup.

Keyboard Shortcuts for Widgets

It is useful to provide keyboard access to widgets, to focus a widget directly and to activate the features within the widget. These may be "mnemonics" that use a letter from the label of the control, as well as other special keys that perform familiar operations on the system. When providing non-standard key commands, document them so the user knows how to use them.

When localizing the user interface, it may be necessary to localize keyboard mnemonics as well in order to keep them apparent. Be sure not to introduce key conflicts when doing this, and ensure that the correct key commands remain apparent to the user.

Example Keyboard Operation: Radio Group/Radio

See working Radio button examples from the University of Illinois.

Key Bindings for Radio Group Behavior - Example
Key Description of Radio Group Behavior
Tab Key If no radio button is checked, focus moves to the first radio button in the group, but the radio button remains unchecked. If one radio button is checked, focus moves to the checked radio button. If SHIFT+TAB is pressed, focus moves to the last radio button in the group, but the radio button remains unchecked.
Space Bar Checks the radio button with keyboard focus (this is a special case when using tab and no radio buttons have been marked as checked).
Down Arrow If no button is checked, check the first radio button. If the last radio button is checked, check the first radio button. Otherwise, move the check from the current radio button to the next radio button.
Up Arrow If no button is checked, check the last radio button. If the first radio button is checked, check the last radio button. Otherwise, move the check from the current radio button to the previous radio button.

In this Radio Group example, the tabindex of the first and last radio button elements has a tabindex="0" (assuming none of the radio buttons is checked), the remaining radio elements have tabindex="-1". As soon as the first or the last radio button receives focus it changes the tabindex value of the other radio button to -1. If none of the radio buttons is selected the and the keyboard focus leaves the group the first and the last radio buttons have their tabindex values set to 0.

Todo: should you discuss what happens when the user tabs to the radio group and no button is checked?

Other Widget Authoring Practices

The Common Widget Design Patterns section of this document contains best practices, such as keyboard navigation, for creating common widgets found on the Web. This section contains miscellaneous authoring practices that you should also consider.

Maintain a valid format for aria-valuenow

It is essential that application vendors maintain a valid format for aria-valuenow, and aria-valuenow should accurately represent the value of the widget.The value must be within range of aria-valuemin and aria-valuemin, where the value of aria-valuemin is less than or equal to the value of aria-valuemax, throughout the life cycle of your widget. If aria-valuemin is not less than or equal to the value of aria-valuemax, or if the aria-valuemax is indeterminate, this creates an error condition that will be handled by the assistive technology, resulting in undesirable results. Should an alternative text equivalent be needed to properly represent the aria-valuenow, such as a day of the week, then you should accompany the aria-valuenow with an appropriate aria-valuetext equivalent such as in this example: 

<div role="slider" aria-valuenow="1" 
	aria-valuemin="1" aria-valuemax="7"
	aria-valuetext="Sunday">

Here the values 1 through 7 represent the days of the week and aria-valuenow of 1 is equivalent to the first day of the week or Sunday. When aria-valuetext is made available aria-valuenow should also be treated as an index which is 1 based.

Providing Keyboard Focus

One way to provide keyboard support in (X)HTML is with form and list elements that accept keyboard focus by default. With the Tab key, the user can navigate to these types of elements. However, when building sophisticated widgets, it's necessary to be able to control keyboard navigation exactly. Authors may require or prefer to use host language elements that do not have built-in keyboard navigation features. For example, the author may wish to provide keyboard navigation without altering the tab order. Navigating within large composite widgets such as tree views, menubars, and spreadsheets can be very tedious and is inconsistent with what users are familiar with in their desktop counterparts. The solution is to provide full keyboard support using the arrow keys to provide more intuitive navigation within the widget, while allowing Tab and Shift+Tab to move focus out of the widget to the next place in the tab order.

A tenet of keyboard accessibility is reliable, persistent indication of focus. The author is responsible, in the scripts, for maintaining visual and programmatic focus and observing accessible behavior rules. Screen readers and keyboard-only users rely on focus to operate rich internet applications with the keyboard.

Using Tabindex to Manage Focus among Widgets

One requirement for supporting the keyboard is to allow focus to be set to any element. The tabindex attribute can be used to include additional elements in the tab order and to set programmatic focus to them. Originally implemented in Internet Explorer 5, the feature has been extended to Opera, Gecko-based user agents such as Firefox, and WebKit-based user agents such as Safari. The following table outlines the use of the tabindex attribute:

Use of the Tabindex Attribute
Tabindex Attribute Focusable with mouse or JavaScript via element.focus() Tab Navigation

not present

 Follows default behavior of element (only form controls and anchors can receive focus.) Follows default behavior of element

zero - tabindex="0"

 yes In tab order relative to element's position in document

Positive - tabindex="X" (where X is a positive integer between 1 and 32768)

 yes Tabindex value directly specifies where this element is positioned in the tab order.

Negative - tabindex="-1"

 yes No, author must focus it with element.focus() as a result of arrow or other key press

Setting a tabindex value of -1 to an element enables the element to receive focus via JavaScript using the element.focus() method. This method is used to enable arrow key navigation to elements. Each element that can be navigated to via arrow keys must have a tabindex of -1 to enable it to receive focus. Here are just a few additional tips to help you with managing keyboard focus:

  • Use focus and blur events (or event delegation) to monitor changes to the current focus - focus and blur events can now be used with every element. Modern browsers now support an activeElement property on the document object to get the focused element. Don't assume that all focus changes will come via key and mouse events, because assistive technologies such as screen readers can set the focus to any focusable element, and that needs to be handled elegantly by the JavaScript widget. Techniques such as "event delegation" (for example, intercepting events on a list rather than on every listitem) can greatly increase web application performance and code maintainability, and authors are encouraged to use JavaScript best practices whenever possible.

    The activeElement property is now standard in HTML 5.

  • Follow keydowns to move focus - A keydown event handler can determine the next object to receive focus and call that element's focus() method.

  • Use onkeydown to trap key events, not onkeypress - Key press events do not fire for all keys and they vary across browsers.

  • Dynamically change focusability using the tabIndex property - You may want to update tabindex values if a custom control becomes disabled or enabled. Disabled controls should not be in the tab order. However, you can typically arrow to them if they're part of grouped navigation widget. When an element receives focus, it should change the tabindex value to 0 to make an element the default element of the widget. This is important if the user leaves the widget and returns to the widget again so focus is on the last element of the widget the user was on. If other elements of a widget can receive keyboard focus, only one element of the widget should have a tabindex value of 0.

  • Use element.focus() to set focus - Do not use createEvent(), initEvent() and dispatchEvent() to send focus to an element, because these functions do not change the focus. DOM focus events are informational only, generated by the user agent after an element has acquired focus, but not used themselves to set focus.

  • The use of :focus pseudo-class selectors to style the keyboard focus is not supported in many versions of Internet Explorer. Authors should use the :active pseudo-class (which older versions of IE treat like :focus) in conjunction with the :focus pseudo-class. Example: a:focus, a:active { text-decoration: underline; }

    If the related CSS pseudo-classes are not appropriate or not supported in all browsers, authors can use JavaScript techniques to indicate an appropriate focus alternative, such as using focus and blur events to toggle a classname on an element.

  • Always draw the focus for tabindex="-1" items and elements that receive focus programmatically when supporting versions of Internet Explorer older than 8 - Choose between changing the background color via something like this.style.backgroundColor = "gray"; or add a dotted border via this.style.border = "1px dotted invert". In the dotted border case, you will need to make sure those elements have an invisible 1px border to start with, so that the element doesn't grow when the border style is applied (borders take up space, and IE doesn't implement CSS outlines).

  • Prevent used key events from performing browser functions - If a key such as an arrow key is used, prevent the browser from using the key to do something (such as scrolling) by using code like the following:

    <span tabindex="-1" onkeypress="return  handleKeyPress();">

    If handleKeyDown() returns false, the event will be consumed, preventing the browser from performing any action based on the keystroke. In addition to the return value the browser must call the event methods that will prevent the default action, for IE this is setting the event property "returnValue=false", and for other browsers supporting the W3C event model this means calling the "preventDefault" method of the event object.

  • <span tabindex="-1" onkeydown="return handleKeyDown();">

    If handleKeyDown() returns false, the event will be consumed, preventing the browser from performing any action based on the keystroke.

  • Use key event handlers to enable activation of the element - For every mouse event handler, a keyboard event handler is required. For example, if you have an onclick="doSomething()" you may also need onkeydown="return event.keyCode != 13 || doSomething();" in order to allow the Enter key to activate that element.

    There are user agent-specific considerations for key event handling.

  • Consider using a "roving" tabindex for complex widgets if you are not using the aria-activedescendant property.

Using activedescendant to Manage Focus for Widget Children

In addition to tabindex, WAI-ARIA provides the aria-activedescendant property for managing the focus of child elements within a widget. Widgets like grid and tree typically manage their children. The root element of the widget should have a tabindex value greater than or equal to "0" to ensure that the widget is in the document tabbing order. Rather than setting a key event handler on each element within a larger component, the event handler can be set on the parent element such as the tree. It is then the job of the parent element to manage the focus of the children.

The parent may use the aria-activedescendant property to indicate the active child. For example, the container element with the role of tree can provide an onkeydown event handler so that each individual tree item within the tree does not need to be focusable and to listen for the keydown event. The container object, in this case the tree, needs to maintain the point of regard and manage which individual child item must be perceived as active.

Important: For a given container widget where activedescendant must cause focus events to be fired to ATs, the actual focus must be on the container widget itself. In HTML this is done by putting tabindex="0" on the container widget.

The key handler on the parent captures the keystrokes and determines what item becomes active next and updates the aria-activedescendant property with the ID of the appropriate, next active child element. The browser takes that ID information and generates the focus event to the assistive technology. Each individual element does not have to be made focusable via a tabindex value of -1, but it must be styled using CSS to indicate the active status.

As active status is moved to the next descendant, ensure that it is scrolled into view using scrollIntoView(). See section Managing Focus with Scroll below for more information.

Managing Visual Focus with tabindex Alone

An alternative to using activedescendant is to have the parent element, in response to the same keyboard input, move focus to its children by first removing tabindex from children that do not have focus, which removes them from the tab order. This would be followed by setting the tabindex to "-1" on the element that is to receive focus and then using script to set focus on the element to receive focus. As with aria-activedescendant, this omits managed children from the tabbing order. It enables browsers that do not yet support aria-activedescendant to maintain keyboard navigation, and it provides notification to many assistive technologies like screen magnifiers to move visual focus without relying on other WAI-ARIA properties. Today, this technique will work in most user agents, but in the long run aria-activedescendant will require less work by the developer.

Although not always ideal based on the widget you are creating, one benefit of using tabindex to manage focus on an element is that the user agent will scroll the element into view when focus is set to the it. This is not the case for aria-activedescendant. When setting or updating the aria-activedescendant property, e.g. aria-activedescendant="cell23", authors must ensure that the element with id="cell23" is in view. In either case, consider positioning your widget in the visible area of your browser to maximize usability. This can be achieved using available JavaScript scrolling functions.

Managing Focus with Scroll

In some browsers, a JavaScript call to scrollIntoView() on this element should suffice, but in browsers where this is unreliable, authors should explicitly set the scrollTop and scrollLeft properties of the "cell23" element and its ancestors to scroll the element into view. scrollTop and scrollLeft adjust the node positions by the amounts(pixels) needed to scroll a node into view.  Scrolling values are adjusted by the amounts(pixels) needed to scroll a node into view. This is done by comparing the sizes of the nodes using available measurements such as scroll+offset+clientWidth/Height/Left/Top. It's important to note that you have to adjust a node so that it's viewable within the context of its parent node.  Then you have to move up the DOM tree and make each parent node visible.

For example, create a custom scrollIntoView() method that is called at various times, including coincidence with the setting of the aria-activedescendant property. The method takes a DOM node argument, say "n". Here is the high level algorithm:

  1. If n is already in view, stop; otherwise, continue.
  2. adjust n.scrollTop and n.scrollLeft such that it is in view.
  3. adjust scrollTop and scrollLeft for the ancestor nodes of n such that that the region of the ancestors which n consumes is visible.

This is a minimum-position-change algorithm.

Understanding how the DOM scrollIntoView works across browsers is important. Browsers (including Firefox3) force the node either to the top or the bottom of the screen (as defined by the single Boolean parameter) even if its already in view. This is problematic when you only need to scroll horizontally to see the element. It is also problematic when the node is partially off the bottom of the screen and the parameter is (true) which forces the node all the way to the top, and vice versa with the top going to the bottom on (false). IE forces the node to the left of the client area (or right in right-to-left mode) even if it's horizontally in view already.

The scrollTop and scrollLeft functions create some challenges. scrollTop is always accurate but misleading with respect to inner (nested) scrollbars. scrollLeft cannot be relied on in right-to-left languages because it is sometimes negative and sometimes positive especially with respect to inner (nested) scrollbars. Different browsers handle right-to-left completely differently.

Managing the Perception of a Dual Focus

Often applications give the perception of having a dual focus. Two examples of this are multi-selection list boxes and selected tabs, within a tablist, when focus is in a tabpanel. In the case of a muti-selection list box a developer may gray selected items as they move focus to list box items to toggle their selected state. In the case of a tabpanel the user selects a tab but then navigates to a focused item in the corresponding tabpanel the tab appears to also have focus. In reality, only one element may have focus in an application. In these scenarios authors should ensure keyboard focus is set on the current element that visibly receives keyboard user input while ensuring other "highlighted" elements have an aria-selected state of "true" until de-selected. When the de-selection occurs, such as when a multi-select item is de-selected or a user moves to a new tab and de-select the old tab, the author should ensure that the visible selection of the de-selected item is removed.

Author-Defined Keyboard Short-Cuts or Mnemonics

Author-defined keyboard short-cuts or mnemonics present a high risk for assistive technology users. Because they are device-, browser-, and AT-dependent, conflicts among key bindings are highly probable. Therefore, if you needed to use accesskey, you should be aware that it will behave differently in
different browsers. It also may not work with small devices so it is still advisable to ensure that all features are accessible with the basic keys like Tab/Shift+Tab, arrow, Enter, Space and Escape.

The XHTML 2 Working Group is currently developing a new Access Module to address this issue and we hope to have it or a feature like it in future versions of (X)HTML. Refer to Section 9: Implementation Guidance.

Supporting Tooltips with the Keyboard

A tooltip is a popup messages typically triggered by moving a mouse over a control or widget causing a small popup window to appear with additional information about the control. To provide simple text tooltips, the HTML title attribute should more than suffice because the user agent will render it for tooltips. When creating a tooltip, it is essential that the user be able to activate it using the keyboard. When a form control or widget receives keyboard focus, the tooltip must display. When the form control or widget loses focus, the tooltip must disappear. Browsers do not currently support this functionality.

The following code snippet from the iCITA site shows the use of a onfocus="tooltipShow();" function to display the tooltip when focus is placed on an element. 

<html lang="en-us"">  
<head>    
   <title>inline: Tooltip Example 1</title>      
   <link rel="stylesheet" href="css/tooltip1_inline.css"  type="text/css">    
   <script type="text/javascript" src="js/tooltip1_inline.js"></script>    
   <script type="text/javascript" src="../js/widgets_inline.js"></script>
   <script type="text/javascript" src="../js/globals.js"></script>          
   <link rel="icon" href="http://www.cites.uiuc.edu/favicon.ico" type="image/x-icon">    
   <link rel="shortcut icon" href="http://www.cites.uiuc.edu/favicon.ico" type="image/x-icon"> 
</head>
   …   

   <body onload="initApp()">

   <div id="container">

   <h1>Tooltip Example 1</h1>
     <h2>Create Account</h2>
   <div class="text">
   <label for="first">First Name:</label> 

   <input type="text"  id="first" name="first" size="20" 
          onmouseover="tooltipShow(event, this, 'tp1');"     
          onfocus="tooltipShow(event, this,  'tp1');" 
          aria-describedby="tp1"  		 
          aria-required="false"/>

   <div id="tp1" role="tooltip" aria-hidden="true">Your first name is optional. </div>    
   </div>
  …

When Keyboard Handlers Shortcuts Steal the Keys

Similar to the tip specified in Using Tabindex to Manage Focus on Widgets, a web application should cancel (or swallow) the keyboard event in the keyboard handler to prevent the key from being used outside the web application. For example if the user presses Control+PageDown in a tab panel in a web application, this keyboard event should not also go to the user agent, which would cycle the active browser tab, confusing the user.

Providing Navigable Structure within Web Pages

This section takes a broader look at the Web page. It is intended to assist you in conveying a logical, usable, and accessible layout to an assistive technology or adaptive system designed to modify the visual layout to meet the users needs.

One of the deficiencies of (X)HTML for disabled users has been the usability of keyboard navigation. Users dependent on a keyboard for navigation have been forced to tab everywhere in the document, as the only keyboard accessible document elements are form and anchor elements. This has forced developers to make most everything a link to make it keyboard accessible, and to get to each link you have to tab to it. With the advent of portals and other content aggregation means Web pages are divided into visible regions and there has been no vehicle to get to them other than perhaps to do things such as:

  • Create a skip link at the top of the page to the main content
  • Make the head of each perceivable region (search bar, stock quote, TV Listing, etc.) an <H1> tag

There are number of problems with this approach:

  • Both force the user interface to change to support accessibility
  • In the case of using <H1> to mark your regions, this is not consistent across Web sites
  • The semantics are limited to main content and a section
  • Neither convey the need for the rich internet application developer to control keyboard navigation to an assistive technology

This remainder of this section provides the author with a playbook for using WAI-ARIA to add semantically rich navigation structure in a Web page so that an assistive technology may provide an effective user experience and avoid these shortcomings.

Steps for Defining a Logical Navigational Structure

Due to the complexity of today's web content, it is imperative that all content reside in a navigation landmark. Sight and mobility impaired users must be able to quickly access a list of landmarks for a web page, to be used as a table of contents. This allows the user to quickly navigate to important sections of the page without "endless" TAB navigation. If this is not done, then content will be orphaned and missed by the user. In fact many of today's accessibility test tools have built-in rules to flag this issue as a compliance error. This section defines how to create these navigable regions of the page:

  1. Identify the logical structure of your page

    Break up your page into perceivable block areas which contain semantically associated information called "regions". You can further break down each region into logical regions as needed. This is a common process undertaken by portal developers who break the page into perceivable regions called portlets. Think about the user wanting to navigate to these logical block areas on your Web page. Write down a description of what you believe each region to be.

    Depending on your Web application you may then need to break it into sub regions depending on the complexity of your Web application. This is a recursive process. A user will look at these perceivable areas like pealing an onion. You might have an outermost collection of perceivable regions or block areas and upon entering each region you may have a collection of regions within it.

  2. Implement the logical structure in markup

    Implementing the block structure in markup often involves wrapping elements contained with a "region" such as a <div> or <iframe> with visible borders so that each region or block is perceivable to the user.

  3. Label each region

    Once you have broken up each region you need to label it. The start of each region must have a perceivable header and it should be used to label the region. For details on how to do this see section 3.4.3.1 Header Levels vs. nesting level to create a header to label each region. If you're finding it difficult to come up with a label for the region, make sure at least to use one of the standard roles defined in the following step. The drawback of not providing a label is that users will not know the purpose of the region. By definition, regions would be included in a summary of a page. If an assistive technology were to summarize it would be unable to provide information about the section without a label.

  4. Assign landmark roles to each region

    Now that you labeled your regions, you need to assign them semantic navigation landmarks. Landmarks are a vast improvement over the rudimentary "skip to main content" technique employed prior to WAI-ARIA. If possible it is best to use these as landmarks. Skip to main content links may impact the placement of web application elements. This may be a consideration for developers that want to try to keep their web application in a specific visible area. Consequently, layout adjustments may need to be made to support skip to main content links. Also, skip to main content links are limited in that they only address only one main content area. WAI-ARIA provides a collection of landmarks which are applied to each of the regions you identified in step 2.

    The presence of common, semantic, navigation landmarks allows each site to support the same standard and allows your assistive technology to provide a consistent navigation experience - an important feature for screen readers and alternate input solutions. For users with cognitive and learning disabilities the landmark information could be used to expand and collapse these regions of your page to aid in simplifying the user experience by allowing the user to manage the amount of information processed at any one time.

    WAI-ARIA landmark roles that are applied to elements having strong native semantics are not mapped consistently to the platform accessibility API. An example is the TABLE element. For this reason, it is recommended that authors apply landmarks to DIV and SPAN containers.

    There are also mainstream benefits of providing navigation landmarks. Your browser may assign key sequences to move focus to these sections as they can be set on every site. Navigation to these landmarks is device independent. A personal digital assistant (PDA) could assign a device key to get to them in your document. The common landmarks in WAI-ARIA include:

    application
    Represents a region of the page representing a unique software unit executing a set of tasks for its users. It is an area where assistive technologies should also return browse navigation keys back over to the web application in this region.

    If the entire web page has a role of application then it should not be treated as a navigational landmark by an assistive technology.

    banner
    A region that contains the prime heading or internal title of a page.
    complementary
    Any section of the document that supports but is separable from the main content, but is meaningful on its own even when separated from it.
    contentinfo
    Meta information which applies to the first immediate ancestor whose role is not presentation.
    form
    A region of the document that represents a collection of form-associated elements, some of which can represent editable values that can be submitted to a server for processing.
    main
    Main content in a document.
    navigation
    A collection of links suitable for use when navigating the document or related documents.
    search
    The search tool of a Web document.

    To set a landmark in your page: 

    <div role="navigation" title="Table of Contents"> … </div> 
<div role="main" title="Game Statistics"> … </div>
  5. For application landmarks with static prose

    If you have a regional landmark of type application and static descriptive text is available, then on the application landmark, include an aria-describedby reference to associate the application and the static text as shown here:

    <div role="applicaton" aria-labelledby="calendar" aria-describedby="info">
<h1 id="calendar">Calendar<h1>
<p id="info">
This calendar shows the game schedule for the Boston Red Sox.
</p>
<div role="grid">
…
</div>
  6. For landmarks unsuited to specialized region WAI-ARIA roles

    You can create custom regional landmarks by using a generic region. While it is not essential to label these specialized regions with a header, you should provide a title to ensure that the region name is accessible to all users, just as you would the standard regional landmarks. See Header levels versus Nesting levels for directions on how to label the region.

    <div role="main"> … <div role="region" title="weather">

    Note: the region role is generic and should only be used when a more specific role is not applicable.

  7. Indicate to the assistive technology who controls the keyboard navigation

    Today's screen readers for the blind have been designed to give the user a "browsing" experience meaning the screen reader consumes a number of keys to aid in the browsing experience. For example, the "up" and "down" arrow keys are used to read the next and previous line of text on your Web page. Accessible rich internet applications will use these keys in an application to navigate within "widgets" like a Tree View.

    Assistive technologies must be able to identify widgets which implement WAI-ARIA and allow them use of the keyboard. However, if you have used numerous widgets to form an application you must set the role on the encompassing region to application. Should you have regions which should be browsed as documents within the application region you should mark those regions with a document role as needed. See section 3.4.2 Structural Roles used to facilitate assistive technology navigation.

Structural Roles that Facilitate Navigation with Assistive Technologies

While WAI-ARIA is designed to address many disabilities, this section is best described in terms of screen reader use. In desktop applications, screen readers typically treat widgets as discrete entities, reading and interacting with each widget one at a time. The user moves the point of focus from widget to widget using tab/shift tab, mnemonics, or accelerators, keyboard commands which are usually provided by the application or the operating system. We refer to this mode of interaction as "application mode."

When viewing Web content however, screen readers often gather information about all the widgets in an area and present them in a document-like view which the user navigates using keyboard commands provided and controlled by the screen reader. Think of this mode as a virtual environment that presents Web content in a way that makes it convenient for adaptive technology users to navigate and read. This is sometimes called browse mode, or virtual mode. We refer to this as "document browse mode."

Because many screen readers provide document mode navigation support using single key mnemonics on the alpha-numeric keyboard, they may provide a third mode, called "forms mode," used to interact with form controls that are encountered in document mode. Behavior in forms mode is similar to that of application mode. The key feature of forms mode is that it can be toggled with document mode to make it easy to both interact with a specific widget, and read virtualized content of which the widget is a part. Since, as described above, a screen reader's perception of an area as either a document or an application greatly influences how the user reads and interacts with it, WAI-ARIA provides content authors a way to indicate whether their pages must be viewed as applications or documents by assistive technologies.

To set document or application mode follow these steps:

  1. Set the Application Role

    After you have divided your Web page into regions through the use of role landmarks and custom regions, you must make a decision: Is your Web page an application or not? If the majority of the content is application-like the default interaction mode should be set to application, with document regions embedded within the application if applicable. Otherwise the default interaction mode is document-like and therefore should not be overridden by the use of a global role of application. In this case the application role can be placed on discrete regions within the document if applicable.

    If it is, set the role of application on the body tag as follows: 

    <body role="application">

    When using application, all static text must be associated with widgets, groups or panes via using the aria-labelledby and aria-describedby properties, otherwise it will not be read by the screen reader when the user navigates to the related widget or group.

    Special Considerations:

    • If you have selected to have a role of application on the body tag, it is recommended that a widget have focus after the page is first loaded. There may be an instance when an application itself needs to receive focus, such as an application consisting solely of a scrollable editable text area.
    • If when your page loads and you should have focus on a widget this is a strong indicator that your Web page should have role of application.
    • If your page has only a few isolated widgets, like pop-up calendars located on a Web page, it is not necessary to expressly set the role of application on the body. Screen readers, based on widget roles, must be able to provide access to these widgets without recognizing the entire page as an application.
    • Also, browsers make use of a feature called the contenteditable attribute, which will be incorporated into HTML 5. Contenteditable allows an author to turn the browser section into a rich text editor, similar to a word processor. Any section which has contenteditable set to "true" is considered a widget.
    • If the body element has been given the role of application, please follow step 3. Otherwise, the Web page is considered a document, and no further action is required in this regard.
  2. Dialogs and alert dialogs - special case application roles

    WAI-ARIA provides dialog and alertdialog roles that are to be treated as special case application roles. Like application, screen readers will leave the main job of keyboard navigation up the dialog.

    When using dialog, all static text must be associated with widgets, groups or panes using the aria-labelledby and aria-describedby properties, otherwise it will not be read by the screen reader when the user navigates to the related widget or group. Unlike an application, your Web page is unlikely to start out as either of these two roles but rather the author is most likely to dynamically create dialogs or alertdialog sections within the Web page.

    Unlike dialog, descriptive text of the alert does not need to be associated via a relationship, as the contents of alert dialogs will be read automatically by the screen reader when the dialog opens.

  3. Set the document role

The default mode for a screen reader to be processing an HTML Web page is document browse mode. This is equivalent to having a role of document on the HTML <body> tag. If you have already specified a role of application on the body tag there may be times in which you tell the screen reader to switch into "document browse mode" and start stealing the necessary keys to browse a document section of your Web page. These keys are the typical keys used by WAI-ARIA widgets and to provide this level of navigation the keys must be stolen from your browser.

To mark areas of your page to tell the assistive technology when to switch into document browse mode, look at the regions/landmarks you have defined and determine which ones must be browsed as a document or navigated as an application. For each region which must be browsed in document browse mode, embed a div element within it with the role of document as follows: 

<div role="document">

Now, when a screen reader encounters this region, it will change its interaction model to that of document browsing mode.

Implicit Nesting and Headings

This section discusses the use of the heading role and nesting levels.

Header Levels Versus Nesting Levels

The heading role value signifies a heading for a section of the document instance. Use of the heading role indicates that a specific object serves as a header. The region of the document to which the heading pertains to should be marked with the aria-labelledby property containing the value of the id for the header. If you have a heading and there is no element containing the content that it heads, wrap the content in a <div> bearing this aria-labelledby attribute. If headings are organized into a logical outline, the aria-level property can be used to indicate the nesting level. Here is an example with and without ARIA. Note that the preferred way is using native semantics without ARIA, but the approach with ARIA is shown first to demonstrate use of the heading role:

Using ARIA:
<div role="main" aria-labelledby="page_title">
  <p id="page_title" role="heading" aria-level="1">Top News Stories</p>
   … main page contents here …
</div>

Using native markup:
<div role="main" aria-labelledby="page_title">
  <h1 id="page_title">Top News Stories</h1>
   … main page contents here …
</div>
Owns Repairs Nesting

Assistive technology briefs users on the context where they are. When they arrive at a new page, a page summary may be given. When they move into a new context, some of the labeling from elements containing the new focus or reading location may be rendered by the assistive technology, to give context to the details to be read next.

The syntactic structure of a page provides the default nesting of contexts. If a paragraph is nested in a <div> or table cell, it is assumed that labels for the <div> or headers for the table cell are pertinent to what is in the paragraph. On the other hand, it is not possible to always flow the logical structure one-to-one into the parse structure.

The aria-owns relationship is provided to annotate logical nesting where the logical child is not a syntactic descendant of the logical parent. In a Rich Internet Application, updates may be made to the document without updating the logical syntactic structure, yet elements may appear to be added to the document structure. From a DOM and accessibility hierarchy perspective aria-owns is a fallback mechanism to using the tree hierarchy provided in the DOM. An example of where aria-owns is needed is a treeitem, where children in a folder subtree are added to a visible subtree but not reflected in the actual document subtree of the folder. The aria-owns relationship can be used to associate the folder with the new "adopted" child. For more details on the use of aria-owns see section 4.2 Owning and Controlling. The aria-owns relationship is used to indicate to a user agent that a menu is an adopting parent of a sub menu. Another use for aria-owns is a hierarchical diagram where the child nodes of the diagram are not be adequately represented using the DOM structure.

Directories, Groups, and Regions

There are several WAI-ARIA roles used to indicate a collection of user interface objects, and each has a distinct purpose:

directory
Contains a static table of contents
group
Small set of related user interface objects that would not be included in a page summary or table of contents by an assistive technology
region
Section of related user interface objects that should be included in a page summary or table of contents.

The use of each is described below.

Directories and Their Applicability

The WAI-ARIA role, directory, allows authors to mark static table of content sections of a document. Prior to WAI-ARIA, the user would need to guess if an area of a document actually pertained to the table of contents. Authors should mark these sections within a document with a role of directory.

<div role="directory">
   <ul>
      <li>Global Warming Causes
          <ul>
             <li>CO2 Buildup</li>
             <li>Auto emissions<li>
             <li>Factory emissions</li>
             <li>Destruction of rainforests</li>
          </ul>

      </li>

      <li>Tailoring CO2 buildup
          <ul>
             <li>Elimination of the incandescent light bulb</li>
             <li>Hydrogen fuel cells</li>
             <li>Solar energy</li>
             <li>Wind power</li>
          </ul>

      </li>  
   </ul>

</div>
Groups and Their Applicability

Authors should use a role of group to form logical collections of items with related functionality in a widget. A group should not be considered a major perceivable section on a page. A group neither has a heading nor appears in the "Table of Contents." A group may delineate a set of treeitems having the same level in the tree or it may be used to group a set of related checkboxes in a form. Other examples include:

  • a row in a grid (a row is a specialized group representing a row in a grid);
  • a group of children in a tree widget forming a collection of siblings in a hierarchy; or
  • a group of items having the same container in a directory

Proper handling of a group by assistive technologies, therefore, is determined by the context in which it is provided. Group members that are outside the DOM subtree of the group need to have explicit relationships assigned for them in order to participate in the group. Groups may also be nested.

If an author believes that a section is significant enough in terms of the entire document instance, then the author must assign the section a role of region or one of the designated standard landmarks. The designated landmark roles are listed in the section Regions and XHTML Role landmarks.

Regions and Their Use

When defining a region for a section of a document, authors must consider using standard document landmark roles defined in the XHTML Vocabulary. This makes it possible for user agents and assistive technologies to treat roles as standard navigation landmarks. If the definition of these regions is inadequate, authors must use the WAI-ARIA region role and provide the appropriate title text.

For more information on the use of region see Regions and XHTML Role landmarks.

 

Remaining Structural Roles

Tabular Structure-Related Roles Supporting Tabular Widgets

A number of structural roles support the tabular widgets, grid and treegrid. These structural roles indicate additional keyboard navigation as well as the ability to select rows and/or columns. Typically, you would apply these roles to an underlying table in the base markup as shown here:

<table role="grid">

However, that may not work for the developer in all instances, such as when the developer has need for a <div> or <span> or when additional semantics are needed. To assist, the following roles are provided to support tabular widgets:

When constructing a grid or treegrid the author must use gridcells for the actual cells:

<table role="grid">
   <tr>
      <td role= "columnheader">Apples</td><td role= "columnheader">Oranges</td>
   </tr>
   <tr>
      <td role="gridcell">Macintosh</td><td role="gridcell">Valencia</td>
   </tr>
</table>

Unlike table cells within a table, authors should ensure a grid's gridcells are focusable through the use of tabindex (in HTML), or aria-activedescendant on the grid.They may also be editable, as is shown in the above example.

Treegrid's may require expanding and collapsing rows which may not be performed using a <tr>. In these instances authors will use an HTML <div>. WAI-ARIA provides a role of row which may be assigned to the <div> to convey to the assistive technology that this is still a row. If you decide to not use the native HTML <table> elements and choose more flexible elements, such as <div> and <span>s, with applied WAI-ARIA roles in this section, you should structurally lay out your elements in line with what you would expect from HTML. All of your rowheaders should be in a row and your gridcells should be children of each subsequent row in the same format as HTML for <td>s and <th>s within <tr>s.

Marking Descriptive Sections

A new feature of WAI-ARIA is the ability to associate descriptive text with a section, drawing, form element, picture, and so on using the aria-describedby property. The use case for aria-describedby is to reference the local id of the long description. The most common use case for longdesc is for the author to create a separate file to describe a picture. It is prefereable to have the descriptive text in prose as well so that it is readily available to all users. This is useful for authors who do not want to create a separate document that contains the description, and for cognitively impaired users who can be confused by context changes when having to go to another page for the description. Yet, like longdesc, descriptive text is treated separately from the short name provided by the title or alt attributes in HTML.

The aria-describedby property allows for the text of hidden elements to be used for accessible descriptions. Some screen reader vendors have used non-standard attributes to provide hidden help text for form elements. In order to standardize this feature, hidden text is exposed in the description property of Accessibility API objects when referenced by aria-describedby. 

<img src="foo" alt="abbreviated name" aria-describedby="prose1">

<div id="prose1">
   The prose in this div describes the image foo in detail.
</div>

This is the preferred vehicle for providing long descriptions for elements in your document.

When the author does not desire the entire descriptive text to be located on the main page, aria-describedby can also be used to point to a link to another page. 

<div id="figuretitle">Figure 1-1: Entity Relationship Diagram showing EMP and DEPT</div>
  <img src="foo" aria-labelledby="figuretitle" aria-describedby="link1">
  <a href="descriptionLocation.html" id="link1">Description of Figure 1-1: Entity Relationship Diagram showing EMP and DEPT</a>
</div>

It is not good practice to use the above pattern when the describing element—the <a> tag with @id='link1'—is hidden, since there is no way for a user to navigate to and activate the link. Use the technique only when the description is not hidden.

Miscellaneous XHTML Section Roles

In order to synchronize with the XHTML Role Attribute module, WAI-ARIA includes two XHTML roles which are neither landmarks nor widgets of any kind. These roles were incorporated to replace standard elements found in host languages. These roles are definition and note. If either role has a corresponding element in the host language, it is recommended that authors use the corresponding element in the host language.

The definition role indicates a definition statement in your document. For HTML developers implementing lists of definitions, we recommend you using the DL, DT, and DD elements rather than marking an arbitrary element with a role of definition. An arbitrary element would be appropriate for inline definitions used in conjunction with the DFN element.

Example of an inline definition with an explicit labelledby relationship:

<p>The doctor explained it had been a <dfn id="placebo">placebo</dfn>, <span role="definition" aria-labelledby="placebo">  
an inert preparation prescribed more for the mental relief of the patient than for its actual effect on a disorder.</span>
</p>

Example of an inline definition with an implicit labelledby relationship determined by nesting:

<p>The doctor explained it had been a <span role="definition">
<dfn>placebo</dfn>, an inert preparation prescribed more for the mental relief of the patient than for its actual effect on a disorder.</span>
</p>

Note: In the case where host language semantics do not allow for implicit nesting of definitions terms inside definition roles, authors should explicitly use the aria-labelledby attribute, even when the definition term is nested in the definition as shown here:

<p>The doctor explained it had been a <span role="definition" aria-labelledby="placebo">
<dfn id="placebo">placebo</dfn>, an inert preparation prescribed more for the mental relief of the patient than for its actual effect on a disorder.</span>
</p>

The following is an example using a definition list:

<dl>
 <dt id="anathema">anthema</dt>
 <dd role="definition" aria-labelledby="anathema">a ban or curse solemnly pronounced by ecclesiastical authority and accompanied by  
excommunication</dd>
 <dd role="definition" aria-labelledby="anathema">a vigorous denunciation : cursor</dd>
<dt id="homily">homily</dt>
<dd role="definition" aria-labelledby="homily">a usually short sermon</dd>  

<dd role="definition" aria-labelledby="homily">a lecture or discourse on or of a moral theme</dd>

</dl>

The note role defines a parenthetic or ancillary remark to the main content of the resource. It also allows assistive technologies to skip over this section of the document unless more information is requested about the main content.

<div role="main" aria-labelledby="foo">
   <h1 id="foo">Wild fires spread across the San Diego Hills</h1>
   Strong winds expand fires ignited by high temperatures …
</div>

<div role="note">
   This article was last updated July 30, 2008 at 6:05PM. 
</div>

Relationships

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Labeling and Describing

Marked up content or widgets will often need additional context to make clear what the meaning or purpose is. It is also reasonable that some content media types will need additional descriptions in another format to give clarity to those who are unable to consume the origin format. These additional meta-content sections are linked together by tagging them as labels or descriptions. WAI-ARIA provides the aria-labelledby and aria-describedby attributes to signal the browser to feed these relationships into the accessibility layer. This layer is then used by screen readers and other accessibility technology (AT) to gain awareness of how disparate regions are actually contextually connected to each other. With this awareness the AT can then present a meaningful navigation model for discovery and presentation of these additional content sections. The user agent itself can also choose to present these insights in a meaningful way. Generally you should always add these attributes to any widgets on your site as they are often merely a construct of HTML and JavaScript which provides no obvious insight as to what the widget's behavior or interactivity is.

Labeling

When using one element to label another use the aria-labelledby by attribute. A label should provide the user with the essence of what the object does. For example, you could have a dialog box erected from HTML <div> and you need to assocate a label for the dialog. With a WAI-ARIA role of dialog, you can indicate its widget type and define a label using an HTML header and then associate that label with the dialog using the aria-labelledby relationship. 
	<div role="dialog" aria-labelledby="dialogheader">
	<h2 id="dialogheader">Choose a File</h2>
	… Dialog contents
	</div>

The section doing the labeling might be referenced by multiple widgets or objects as these need only reference the same id, so contextual description may not always be viable. The labelledby attribute can have multiple ids specified as a space separated list much like applying multiple classes to a single DOM object.

The aria-labelledby property can be used to label all visual objects, however it should be noted that (X)HTML provides a @for attribute on the label element which is used to label form controls. Use this attribute where possible and valid. Because the aria-labelledby attribute accepts multiple IDREFs, it is recommended that authors use aria-labelledby for labeling elements that require more than one label string.

Some elements receive their label for embedded text content, but that is the exception.

Often user agents will operate with images turned off for network performance reasons. In these situations, alt text is provided in the place of the image. When the host language provides alternative text capability it is recommended that authors use the alternative text to support these situations and not use separate labeling as a replacement.

Describing

Using aria-describedby

When one element describes another, use the aria-describedby attribute. An aria-describedby section provides further information about a given object or widget, which may not be intuitively obvious from the context, content or other attributes. For example, a fake window is a common widget used in Web applications and is often constructed using a div absolute positioned in a layer above other content. To simulate common window behavior look and feel there is often an X box in the corner which, when activated, dismisses the window widget. One common way to make this X box is to simply make a link whose content is an X. This doesn't give a non-visual user much to go on and belies the real purpose of the X link. To help we add more descriptive text stored elsewhere in the page like this: 

<button aria-label="Close" aria-describedby="descriptionClose" 
    onclick="myDialog.close();">X</button>
and then elsewhere in the HTML 
<div id="descriptionClose">Closing this window will discard any information entered and 
return you back to the main page</div>
Like labelledby, describedby can accept multiple ids to point to other regions of the page using a space separated list. It is also limited to ids for defining these sets. In our contrived example we would also want a good labelledby section to fully explain what the window does and how closing will effect the task being worked on. If an object or widget lacks describedby the user agent or AT may try to extract information from the label or th tags, if present. The label and th tags have limited use in that they can only be applied to forms or tables, respectively.

Using a tooltip as a description

WAI-ARIA also defines the tooltip role to which aria-describedby may reference an author defined tooltip. The assistive technology can tell from the type of object describing the document element what the purpose of that element is. For example, a screen reader could announce the tooltip without the user having to wave the mouse over the element by following the describedby relationship to a document area with a tooltip role. The aria-describedby property is also useful for describing groups.

Here is a code snippet showing a set of the tooltip: 

…    
  <div class="text">
    <label for="first">First Name:</label>
      <input type="text"               
          id="first"           
          name="first"            
          size="20"           
          onfocus="tooltipShow(tooltip1);"          
          onblur="tooltipHide(tooltip1);"
          onmouseover="tooltipShow(tooltip1);"           
          onmouseout="tooltipHide(tooltip1);"           
          aria-describedby="tp1"
      />
  <div id="tp1" class="tooltip" role="tooltip">Your first name is optional</div>    
  </div>    
…

Descriptions on external pages

The aria-describedby property is not designed to reference descriptions on an external resource—since it is an IDREF, it must reference an element in the same DOM document. This is different from the HTML longdesc attribute, which accepts any URI. In general, the preferred pattern for WAI-ARIA applications is to include all relevant resources in the same DOM, But if you wish to reference an external resource with aria-describedby, you can reference a link that in turn references the external resource. This requires the user to follow two steps, first following the aria-describedby arc, then following the link, but does address the use case. The following example demonstrates this:

<p>
   <img
       src="images/histogram.png"
       alt="Histogram of Blackberry tree heights"
       width="40%"
       aria-describedby="longdesc1"
   />
</p>

<p>
    <a id="longdesc1" href="blackberry-description.html" target="_description">Data for Blackberry Histogram</a>
</p>

It is not good practice to use the above pattern when the describing element—the <a> tag with @id='longdesc1'—is hidden, since there is no way for a user to navigate to and activate the link. Use the technique only when the description is not hidden.

Owning and Controlling

Two relationships expand the logical structure of a WAI-ARIA Web application. These are aria-owns and aria-controls .  The aria-owns relationship completes the parent/child relationship when it cannot be completely determined from the DOM created from the parsing of the markup. The aria-controls relationship defines a cause-and-effect relationship so that assistive technologies may navigate to content effected by and changes to the content where the user is operating.

The Owns Relationship

In addition to WAI-ARIA role and state information, for a document element, an assistive technology needs to convey its context. In the case of a treeitem, it is important to know the parent (container), which may provide a folder depth and the number of siblings in the folder. This containment hierarchy can often be determined by the DOM tree, as it provides parent, siblings, and children for a given document element. That said, the DOM hierarchy is rigid and acyclical in that each node may only have one parent. In some situations, a child is reused by multiple parents or a child is separated from its sibilings or parent in the DOM tree. One example is when a radio button appears in a table but it is not a DOM child of the radiogroup, due to the authors use of a table for formatting and the placement of the radio buttons placing them outside the radiogroup container. To solve this problem WAI-ARIA provides the aria-owns property.

The aria-owns property is set on a document element, and its values are the unique IDs of all the adopted children. These elements may appear anywhere in the DOM, yet they are treated as siblings of each owning parent. This example illustrates a radiogroup that first uses the DOM hierarchy to convey context and then aria-owns:

First, consider the preferred method for using the W3C DOM to describe the relationship between radiogroup and radio roles for HTML:

<div id="radio_label">My radio label</div>
<ul role="radiogroup" aria-labelledby="radio_label">
<li role="radio">Item #1</li>
<li role="radio">Item #2</li>
<li role="radio">Item #3</li>
</ul>

In this example, the elements with role="radio" are child nodes of the parent role="radiogroup" element node.

Now, consider an alternative method using the aria-owns property to describe the parent-child role relationship between radiogroup and radio roles for HTML:

<table>
<tr>
<td role="radiogroup" aria-owns="myradio1 myradio2 myradio3" rowspan="3" >
My Radio Label
</td>
<td id="myradio1" role="radio">Item #1</td>
</tr>
<tr>
<td id="myradio2" role="radio">Item #2</td>
</tr>
<tr>
<td id="myradio3" role="radio">Item #3</td>
</tr>
</table>

The aria-owns property should be used sparingly, since it increases the computational load on assistive technology to provide alternative renderings. Also, when accessing the DOM and enumerating children of a DOM node, an AT should then enumerate the adopted children using the aria-owns property. At that instance of walking the DOM, the parent of the adopted children is the adopted parent and not the DOM parent. This will avoid recursion problems.

Each child, adopted or natural, should have the appropriate aria-posinset and aria-setsize properties set consistent with their rendering, if these cannot be determined from the DOM from a direct parsing of the host language. Places where direct parsing does not allow the user agent to determine aria-posinset and aria-setsize are long lists where only the currently visible items are loaded (via Ajax). If the children are re-sorted then the aria-posinset and aria-setsize values should be updated consistent with their visual rendering. Rather than setting size only on a container, content authors should specify aria-setsize on each member of a set to avoid performance issues.  If this property is not set, the user agent must compute and set the property on supporting roles.

Platform accessibility API mappings must invert this relationship for assistive technologies, so that they may determine the owning parent from a child and couple it with aria-posinset and aria-setsize information to provide context information to the user.

 Using Owns with Reusable Content

If you are re-using content across different, transient sections of content by restyling it to render it in association with a different object, you need to maintain the aria-owns property as well to match the current use and apparent ancestry of the reused sub-section. A good example of this is a context help menu that resides at the end of the document. When the user wishes to launch the context help menu in association with different visual elements, styling is used to render the menu in context with that object. Prior to rendering the visual submenu you should ensure the object to which you have requested help assigns its aria-owns property value to the submenu ID. When the menu closes you can remove the aria-owns property.

The Controls Relationship

In rich internet applications document elements may control the behavior on another part of Web page outside themselves. The aria-controls attribute indicates cause-and-effect relationships between document elements.

An example might be a group of radio buttons that "control" contents of a listbox in another part of the page. Here, you would want the radio group to assign a aria-controls relationship to the listbox which will be updating without a page reload. The user, through their assistive technology, can then navigate to the listbox by following the aria-controls relationship when a different radio is selected, to see how the contents changed in the listbox. The ability to update parts of a page without a page reload is a common practice of applications making use of Ajax. Without the aria-controls attribute, a user would be unable to effectively use these types of Web pages as assistive technologies often will not make the user aware of what is happening outside the context of the element the user is currently operating.

With the aria-controls attribute the user may use the assistive technology to follow the relationship to the object it is controlling. It is extremely important for an assistive technology to present changes in the document in response to user input. Therefore, an assistive technology immediately presents changes to a live region when the controlling widget is the one which has user keyboard focus. For example, if a tree view controls a help document pane, each time
the tree item changes the new tree item and then the new help contents should also be read. In the case of a screen reader, the amount of information read in the target live region is dependent on how the live region is configured.

The aria-controls attribute takes one or more ids which refer to the document element. If this relationship is not implied by the host language semantics, then the controlling element must be given a controls attribute with the IDs of the other elements where the changes will show up listed in the attribute value.

Changing the Reading Flow

(X)HTML suffers from a number of disadvantages in keyboard navigation today. One such example is the restriction of navigation to the tabbing order. This is a common problem with presentations in office suites where the logical, perceivable, navigation order of a slide may not match the tabbing order. Sighted users may see a logical navigation process (such as visual steps in the process for assembling a lawn mower). This "flow" is not conveyed by the tab order. The user might tab from step 1 and land on step 4. Another problem is the construction of model-based authoring tools on a Web page. In a model-based authoring tool, a visual object may provide a number of paths that the user can take, such as a multiplexor, which may have output that logically flows to a number of optional electronic components in a drawing. In Web 2.0, developers are actually creating drawings like this to perform tasks such as visually model a work flow. In this scenario, the user will want to decide which object they will navigate their screen reader or alternate input device to next.

Although it is recommended that Tab order follow the reading flow, there may be instances where this is not possible. For these reasons, WAI-ARIA provides a relationship property, called aria-flowto. This allows the author to provide an assistive technology with alternative navigation flows through the document that best represents the author's intent and which is more logical for people with disabilities. aria-flowto establishes the recommended reading order of content, so that the an assistive may overriding the default of reading in document order to its user. aria-flowto does not change the keyboard navigation order of the browser.

Consider the first case of changing a basic reading flow to circumvent (X)HTML tabbing. A good example of this is a logical reading flow in a portal with landmarks. In the future, the user may wish to change the reading flow based on the order of priority with which they navigate a personalized Web application. In the following example, the navigation would follow the order of "Top News Stories", "television listings", "stock quotes", and "messages from friends" by following (X)HTML document reading order. However, the author or end user may determine that the main content is most important, followed by "stock quotes", "messages from friends", and then "TV listings." The end user can change the order if the web page or assistive technology provides an interface for such personalization.

<html>  
…  
<div role="main" title="Top News Stories" id="main" aria-flowto="stock"></div>  
<div role="complementary" title="television listings" id="tv"></div>
<div role="complementary" title="stock quotes" id="stock" aria-flowto="messages"></div>
<div role="complementary" title="messages from friends" id="messages" aria-flowto="tv"></div>

The second use case is such that the Web developer may wish to circumvent the flow by branching to multiple paths in the Web page, requiring the assistive technology to present a collection of options where the user could go next. This is important for work flows or business process management applications. More of these applications are becoming Web based, and a vehicle is required to tell the user how to get through the work flow. The flowto property takes multiple idrefs, allowing the author to define each object the user could flow to. To implement this technique do the following.

Popups and drop-downs

In order for menus, menubars, and menuitems to indicate that it opens a menu, set its aria-haspopup property to "true." The type of menu being launched (submenu, context help, etc.) is not explicitly indicated with WAI-ARIA but is based on the operational characteristics (keyboard and mouse commands).

Combo boxes, or drop down lists, work differently. Controls with the role combobox must contain a list of items that can be opened, usually as a drop-down. Because this is intrinsic to the functionality of a combo box, it does not need to be explicitly indicated with aria-haspopup.

The following html fragment shows the use of aria-haspopup with a menubar, its menus, and submenus. All of the menuitems associated with the menubar have aria-haspopup set to 'true'. Also, the "Zoom" menuitem of the "View" menu has an aria-haspopup property as it leads to a submenu.

<div role="menubar">
  <!--
    File menu: File menuitem has an aria-haspopup attribute set to 'true'.
    That popup div follows immediately below.
  -->
  <div role="menuitem" aria-haspopup="true" id="fileMenu">File</div>
  <div role="menu" aria-labelledby="fileMenu">
    <div role="menuitem">Open</div>
    <div role="menuitem">Save</div>
    <div role="menuitem">Save as …</div>
    …
  </div>
  <!--
    View menu:
  -->  
  <div role="menuitem" aria-haspopup="true" id="viewMenu">View</div>
  <div role="menu" aria-labelledby="viewMenu">
    <div role="menuitem">Normal</div>
    <div role="menuitem">Outline</div>
    <!--
      The View's Zoom menuitem has aria-haspopup='true' as it leads to a
      submenu.
    -->
    <div role="menuitem" aria-haspopup="true" id="zoomSubMenu">Zoom</div>
    <div role="menu" aria-labelledby="zoomSubMenu">
      <div role="menuitem">50%</div>
      <div role="menuitem">75%</div>
      <div role="menuitem">100%</div>
      <div role="menuitem">150%</div>
      <div role="menuitem">200%</div>
    </div>
  </div>
</div>

Managing Dynamic Changes

This section has had only minor edits since it was integrated from APG version 1.0 -- a complete APG taskforce review is pending.

Managing Content and Presentational Changes

General rules for managing content and displaying information

If you are refreshing areas asynchronously, then you need to designate live regions. The following sections explain how to implement live regions and when to use roles that are considered "live" sections by default, including alert, status, or log.

Implementing Live Regions

Live regions are parts of a Web page that the author expects to change. Examples of live regions include dynamically updated content (sports stats, stock information), logs where new information is being added (chat transcript logs), notification areas (status, alerts), etc.

Live regions enable assistive technologies, such as screen readers, to be informed of updates without losing the users' place in the content. Live region settings provide hints to assistive technologies about how to process updates. Note that the assistive technology is responsible for handling these updates and enabling users to override these hints.

The section on Live Region Properties and how to use them gives the details of how to apply live region properties. This process will help rich internet application (RIA) developers to set live region settings that will provide a good user experience for most assistive technology users with little configuration on their part. When applying these live region properties, it is recommended that you conduct user testing. If the AT supports scripting of the response to live regions you may wish to customize the response, such as through a screen reader script for your Web page.

  1. Identify the live regions

    Live regions are any region on a page that receives dynamic updates through client-side scripting. Note the regions of your page that will be live.

  2. See if any of the special case live regions meet your needs

    WAI-ARIA provides a number of special case live region roles whose live region properties are pre-defined and which you may use. If one of these live region roles meet your needs just apply the specific role to the region of the Web page.

  3. Decide the priority of each live region

    When a live region changes, should the user be notified of the change? Notifications could include a sound for a screen reader user. (For simplicity, we will use the case of an audio notification in this discussion.) The shorter the interval between changes and the less important the information, the less likely that the user needs to hear every change. A simple example of changes that should not be heard are changes to time; a sound for every second would be very annoying.

    If the user should hear the change, should the change be announced immediately, as soon as possible, or only when the user is idle? Announcing a change immediately can be disorienting for users, so that should be done sparingly. Most updates should probably only be announced when the user is idle.

    After you have decided the priority for each live region, then decide the live property value:

  4. Decide how much context is needed for each update

    When part of a live region changes, how much context is needed to understand the change. Does the user need to hear the entire live region or just the change by itself?

    If the user needs to hear the entire live region, then mark the entire live region with aria-atomic="true".

  5. Decide what types of changes are relevant for each live region

    Three possible types of changes are: additions, removals, and text. Additions means new nodes are added to the DOM; removals means nodes are removed from the DOM; and text means changes are solely to the textual content. Should the user hear all types of changes or only certain types?

    By default, the user will hear additions and text type changes. If you wish to explicitly define the types of changes, you need to set relevant="THE_TYPES_OF_CHANGES". If more than one type of change is relevant, the types are separated by a space. For example, to define additions and removals as relevant but not text, set relevant="additions removals".

Live Region Properties and How to Use Them

One of the most important concepts behind live regions is politeness. Politeness indicates how much priority a live region has. The following politeness values are available for aria-live: off, polite, and assertive.

aria-live="off"
This is the default. Any updates made to this region must not be announced to the user. live="off" would be a sensible setting for things that update very frequently such as GPS coordinates of a moving vehicle.
aria-live="polite"
Any updates made to this region should only be announced if the user is not currently doing anything. live="polite" should be used in most situations involving live regions that present new information to users, such as updating news headlines.
aria-live="assertive"
Any updates made to this region are important enough to be announced to the user as soon as possible, but it is not necessary to immediately interrupt the user. live="assertive" must be used if there is information that a user must know about right away, for example, warning messages in a form that does validation on the fly.

There are times to suppress AT presentation changes while a region is updating. For that you can use the aria-busy property.

aria-busy="true"

To suppress presentation of changes until a region is finished updating or until a number of rapid-fire changes are finished, set aria-busy="true" and then clear the attribute when the region is finished. While it is busy, the AT will track and collate the changes. It will finally speak the changes once the region is no longer busy.

When a live region is updated, the update can often be announced on its own and still make sense. For example, if a news headline is added, it would make sense to simply announce the headline. However, sometimes the entire live region must be read in order to give the user enough context to make sense of the update. For example, it would not make sense to only give the current value of a stock without saying the name of the stock. The atomic setting gives assistive technologies a hint about which of these cases an update falls into.

aria-atomic="false"
This is the default. It means that when there is a change in the region, that change can be presented on its own; the AT should not present the entire region. atomic="false" is generally a good idea as it presents users with only changes and does not cause them to hear repetitive information that has not changed. However, Web developers should take care that the changed information, when presented by itself, can still be understood and contextualized by the user.
aria-atomic="true"
If atomic is set to "true", it means that the region must be presented as a whole; when there is a change, the AT should present the entire region, not just the change. atomic="true" can make it harder for users to understand changes as the changed areas are not presented independently. atomic="true" can also be annoying as it can force users to listen to repetitive information that has not changed. However, atomic="true" is necessary in cases where the change, when presented by itself, cannot be understood and contextualized by the user. Note that when aria-atomic="true", the AT will attempt to speak the atomic region only once when multiple changes occur in the same region and it hasn't been spoken yet.
Not all updates to a live region are relevant. For example, if the oldest headline in a list of headlines is removed and a new headline is added, the removal of the oldest headline is probably not important enough to announce to the user. However, in a chat application, when a user leaves the chat and their username is removed from the list of users, that removal may be important enough to announce. The relevant setting gives a hint about what types of changes are relevant and should be announced. Any change which is not relevant will be treated as if the region had live="off" and will not be announced. Multiple types of changes can be listed as relevant; the types are separated by a space. The default is relevant="additions text" and this is the most common use case. If the default is applicable to your application, you do not need to provide the relevant property explicitly.
aria-relevant="additions"
Insertion of nodes to the live region should be considered relevant.
aria-relevant="removals"
Removal of nodes to the live region should be considered relevant. Often, removals are not relevant because nodes are removed to make space for new information - e.g. a log implemented as a table where items are taken off the top. However, in the case of something like a buddy list, it is relevant if a buddy is removed. It doesn't require the screen reader to speak the removal, but it notifies the screen reader that it could be useful to do so. Use of aria-relevant="removals" or aria-relevant="all" should be used sparingly. Notification of an assistive technology when content is removed may cause an unwarranted number of changes to be notified to the user.
aria-relevant="text"
Changes to the textual content of nodes that already exist in the live region should be considered relevant. Textual content includes text equivalents, such as the alt attribute of images.

This example shows two live regions. If both regions update simultaneously, liveRegionA should be spoken first because its message has a higher priority than liveRegionB. 

<div id="liveRegionA" aria-live="assertive">         
</div>         
<div id="liveRegionB" aria-live="polite>         
</div>

Choosing Between Special Case Live Regions

You may wish to use a special live region role instead of applying live region properties. WAI-ARIA contains a number of standard roles which are by default considered "live" sections of your Web page. It is important to know when to use these and when to create a custom live region on your known. Here are some rules of thumb:

alert - You must use the alert role for a one-time notification which shows for a period of time and goes away and is intended to alert the user that something has happened. The assistive technology should be notified by the user agent that an alert has occurred, if your operating system supports this type of event notification. When choosing to use alert you should use the alertdialog role instead if something inside the alert is to receive focus. Both alert and alertdialog appear to pop-up to the user to get their attention.

status - You must use the status role when you want to mark an area which is updated periodically and provides general status of your Web application. Changes in status are not typically announced automatically by an assistive technology. However, it is possible to configure some assistive technologies, such as a scriptable screen reader, to watch for changes in the status bar and announce them. Using the status role is also important in that the user could always check the status section for changes in status on different Web pages. Many applications provide status widgets and they are often found, visibly, at the bottom of the application and contain a variety of widgets within it to convey status. The use of status does not guarantee how the AT will respond to changes in the status. The author can still put live="off" or live="assertive" to influence the ATs treatment of the status.

timer - You must use a timer role when you want to mark an area which indicates an amount of elapsed time from a start point, or the time remaining until an end point. The text encapsulated within the timer indicates the current time measurement, and are updated as that amount changes. However, the timer value is not necessarily machine parsable. The text contents MUST be updated at fixed intervals, except when the timer is paused or reaches an end-point.

marquee- You must use a marquee role when you need to mark an area with scrolling text such as a stock ticker. The latest text of the scrolled area must be available in the DOM. A marquee behaves like a live region, with an assumed default aria-live property value of "polite."

log - You must use log if you have a live area where new information is added, like a scrolling chat log of text. Unlike other regions, implied semantics indicate the arrival of new items and the reading order. The log contains a meaningful sequence and new information is added only to the end of the log, not at arbitrary points. If you have a chat text entry area you should indicate that it also controls the aria log aria like so:

<div contenteditable="true" role="log" id="chatlog">
</div>


<label id="gettext">Send Text</label>
<div aria-controls="chatlog" 
     role="textbox" 
     contenteditable="true" 
     aria-labelledby="gettext">
</div

live region - If you have some other live area use case, WAI-ARIA allows you to mark an area using the aria-live attribute. This accompanied by the collection of attributes which support the live property allow you to create your own custom live area on your Web page. For more details regarding live regions refer to the live region section of this guide.

Live region roles that are applied to elements having strong native semantics are not mapped consistently to the platform accessibility API. An example is the TABLE element. It is recommended that authors apply live regions to DIV and SPAN containers. For example: 

<!-- Live region 'log' role used with TABLE element:  the 'log' role is not consistently mapped to platform AAPI. -->
<!-- Do not use. -->
<table role="log" … >
  …
</table>

<!-- Wrap the TABLE element in a DIV with role 'log' instead: -->
<div role="log" … >
  <table … >
    …
  </table>
</div>

Presentation Role

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

This section describes the presentation role, including the conditions under which it is inherited by an element's children.

Rationale

Authors devote a good deal of effort to the appearance of their web pages, and this is especially true in the case of scripted web applications. To this end authors employ various elements purely for visual presentation. For example, <img> elements are used for spacing and decoration; and <table>s are used to create a column based layout. Elements used strictly for presentation are semantically neutral and irrelevant in terms of accessibility. It is necessary to mark such elements as presentational so that they do not appear in the accessible tree created by the user agent. For example, a current technique used with spacer images is to provide blank alt text to indicate that the image is not meaningful. User agents will not publish any information about images with blank alt text to the platform accessibility API.

There are elements other than <img> and <table> that are used solely for visual presentation. Any element is a potential candidate for presentation, and, if so used, these elements also need to be marked as semantically neutral.

It is important to separate content and presentation. CSS 3 has introduced new table layout functionality to allow a user agent to layout content using CSS. There are many advantages to using this feature of CSS such as browser style sheet caching and improved adaptability to mobile devices with limited screen real estate. There are, however, cases where presentational markup cannot be avoided. In such instances, authors are counseled to consult WCAG 2.0 for more detailed guidance.

WAI-ARIA introduces the presentation role as a general device for marking elements as presentational. The presentation role overrides the element's native implicit role, and informs the user agent to not publish the element to the accessiblity API. In fact, the preferred way to mark <img> elements as decorative is to use a role="presentation" attribute instead of (or in addition to) an empty alt attribute. Here is a code fragment sample:

<!-- [role="presentation"] informs the user agent that the spacer images are for layout only. -->
…
<h2>Other Histories of Architecture</h1>
<p>
  <a href="www.somewhere.com">Ancient Roman Architecture</a>
  <img src="spacer.png" role="presentation">
  <a href="somewhere.else.com">19th Century Italian Architecture</a>
  <img src="spacer.png" role="presentation">
  <a href="www.elsewhere.com">Modern Buildings more than 100 Years Old</a>
</p>

<h2>Modern Building Design</h1>
…

The resulting accessible tree is shown below. Note that none of the spacer <img> elements are present:

Inheritance of Presentation by Parent Element's Children

In general, the presentation role is not inherited by an element's children. The exceptions are elements whose role entails that the element has required owned children. Examples include the <table> element and list role, and these exceptions are discussed further below. For all other elements, only the element marked presentational is eliminated from the accessible tree. Note, however, that its contents are published; in particular, the element's textual content is published, but any attributes of the element that may form a text-equivalent are not. For example, a header element with a presentation role would not appear in the accessible tree, but its text does. An image with a role of presentation is not exposed in the accessible tree, nor is the contents of its alt attribute. This is shown in the following code fragment:

<!-- 1. [role="presentation"] negates the implicit 'heading' role semantics but does not affect the contents. -->
  
<h1 role="presentation">Presentation role overrides Header role</h1>
<h1>Another header</h1>
  
<!-- 2. [role="presentation"] hides the image from the accessibility API and does not publish the alt attribute contents. -->
  
<img role="presentation" alt="This text will not appear in the Accessibility API" src="…">

The first header element is absent from the accessible tree for the above example, but its text appears. The second header element is present as a heading. The img element is not exposed at all:

Be aware that the markup <img role="presentation" alt="non-empty alt text"…> is in fact contradictory: Declaring a role of presentation says that the image is for layout, is decorative and meaningless, whereas the non-empty alt text implies that the image is meaningful. It is recommended that authors instead use empty alt text (alt="") where they use role="presentation".

Earlier it was noted that the presentation role is not generally inherited by an element's children. The exception are roles that have required owned elements. Examples include the <table> element, and the list and tree roles. A list is required to have listitem children; a tree, treeitem children. The <table> element's child components are <tbody>, <thead>, <tfoot>, <th>, <tr>, <td>, and <caption>. These component elements would not appear in the markup without the enclosing <table> root element. Thus, when a table is used for layout, it follows that all of its component elements are present in the markup for layout as well. Since annotating all the required child elements with role="presentation" is error prone and difficult to maintain, it is sufficient to mark the table root element as presentational. The presentation role propagates to all the table component elements. However, as before, the contents of the table elements do appear in the accessible tree. Here is an example:

<!-- Layout table marked with [role="presentation"]. -->

<table role="presentation">
  <tbody>
    <tr> <td>Some text</td> <td><p>Paragraph</p></td> </tr>
    <tr> <td><a href="www.somewhere.com">Link text</a></td> <td><img src="meaningful.jpg" alt="meaningful image"></td> </tr>
  </tbody>
</table>

All table specific elements (table, tr, td, etc.) are eliminated from the tree by inheriting the presentation role, but other elements and textual content in the table cells are exposed:

The same logic applies to other roles that have required owned children, such as a list. If the list's root element is declared presentational using role="presentation", all of its listitem elements inherit the presentation role, and none of the list item elements appear in the accessible tree. However, the contents of each list item, that is, other elements and textual content, are included in the tree.

Overriding Presentation

The presentation role is overridden in some circumstances. Recall that the presentation role informs user agents that certain elements are semantically neutral, and are irrelevant for accessibility. If, however, there is an aspect of an element that makes it meaningful, it is no longer neutral, and cannot simultaneously be presentational. The Core Accessibility API Mappings describes the cases where this occurs:

These situations entail that the given element is semantically relevant and will appear in the accessible tree. Marking the element with a role="presentation" is an error, and user agents will ignore the presentation role in these cases. Authors are advised to not mark an element with a role of presentation when it has any of the above properties; rather, to use a role that reflects the element's purpose.

Form Properties

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

This section identifies authoring practices for elements used as form elements.

Use aria-invalid and aria-required To Improve Access to Forms

Until the introduction of WAI-ARIA's aria-invalid state and aria-required property, only presentational strategies have been available to Web content authors to indicate that certain form fields and controls are required or invalid. In applications, these states are only available through styling or varying markup, which is inconsistent, and therefore is inconclusive. In Web-based forms, fields required may be marked by an asterisk. Forms submitted with required data missing or improperly specified may be redisplayed with the unacceptable elements highlighted in red. The assistive technology user is poorly served by such imprecise methods, and all users confront inconsistent indicators for consistent situations.

The WAI-ARIA invalid state and required property provide:

Alert the User When Maximum Length Value Is Reached

When a text input field that has a maximum length value (or the host markup language's equivalent) receives focus, the value defined for "maximum length" should be communicated to the user. When text entry reaches that maximum length (or the markup language's equivalent), an alert (expressed in accordance with user preferences and capabilities) should inform the user that the maximum length for a given field has been reached. Such an alert can be expressed programmatically or, using as an aural icon, by using a WAI-ARIA alert; the user agent may alert the user through a system beep and by triggering the operating systems' "show sounds" facility. When maximum length (or the markup language's equivalent) is reached, the user must then be able to move to another form field in a manner consistent with tab-navigation for that document.

Automatic Focus Changes

Having a user agent automatically change focus in a form in response to user input can be advantageous in situations where that change saves the user keystrokes or on-screen keyboard interaction in order to manually move the focus from one field to another. However, as with form auto-completion, this type of text input event must be firmly under user control because this may not have been the user's intention and some users with disabilities may become disoriented such as those with sight impairments. Consider these cases:

Form Auto-submit

Use caution when using automatic submission of a form without explicit user command or in response to a user-defined setting that permits such behavior, as expressed by the Priority 1 UAAG 1.0 Checkpoints 7.1, 7.2 and 11.1. Unless the user has specifically chosen to set the user agent to allow auto-submission, authors are advised not to set onChange or onFocus events either to trigger submission of a form or to provide an auto-submission event upon completion of all or all required fields of a form or input field.

Math

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Editors' note: This section was added as part of disposition of comment 4, but is very incomplete. The section needs to be reordered, so that instructions on how to use the math role properly appear before considerations of legacy content and negative examples (such as the use of generic HTML to approximate a visual representation of a mathmatical expression). It needs more introductory text about how to use math. The examples need better introductions, and the positive examples should preceded the negative examples, which need to be explained more fully.

There exists significant amounts of legacy content that uses images and/or textual approximations to represent mathematical expressions. Examples of this include the use of ASCII art and/or the misuse of HTML tags -- in particular, SUB and SUP -- to achieve a visual approximation of a mathematical expression, one which is void of the structure needed to render mathematical expressions inherently meaningful.

Use of generic HTML to approximate a visual rendering of a mathematical expression:

<i>a</i><i>x</i><sup>2</sup> + <i>b</i><i>x</i> + <i>c</i> = 0

Accessible example of the same function, using the math role, appropriate label, and MathML rendering:

<div role="math" aria-label="a times x squared plus b times x plus c equals 0">
  <math xmlns='http://www.w3.org/1998/Math/MathML'>
    <mrow>
      <mrow>
         <mrow>
            <mi>a</mi>
            <mo>&#x2062; <!-- invisible times --></mo>
            <msup>
              <mi>x</mi>
              <mn>2</mn>
            </msup>
         </mrow>
         <mo>+</mo>
         <mrow>
            <mi>b</mi>
            <mo>&#x2062; <!-- invisible times --></mo>
            <mi>x</mi>
         </mrow>
         <mo>+</mo>
         <mi>c</mi>
      </mrow>
      <mo>=</mo>
      <mn>0</mn>
    </mrow>
  </math>
</div>

Similarly:

<i>f</i>(<i>x</i>) = <i>x</i><sup>2</sup> + <i>x</i> - 2

Accessible example of the same function, using the math role, appropriate label, and MathML rendering:

Todo: add aria-label here also

<div role="math">
  <math xmlns='http://www.w3.org/1998/Math/MathML'>
    <mrow>
      <mrow>
         <mi>f</mi>
         <mo>&#x2061;</mo>
         <mrow>
            <mo>(</mo>
            <mrow>
               <mi>x</mi>
            </mrow>
            <mo>)</mo>
         </mrow>
      </mrow>
      <mo>=</mo>
      <mrow>
         <msup>
           <mi>x</mi>
           <mn>2</mn>
         </msup>
         <mo>+</mo>
         <mi>x</mi>
         <mo>&#x2212;</mo>
         <mn>2</mn>
      </mrow>
    </mrow>
  </math>
</div>

Drag-and-Drop Support

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Drag-and-drop operations are a common feature of Rich Internet Applications (RIAs). Drag-and-drop features have traditionally challenged people with functional disabilities. These problems arise from the difficulty of manipulating the mouse, finding targets capable of receiving the object being dragged, and actually moving the object to the drop target. Screen readers and alternate input systems assist the user to some degree by allowing the user to simulate a click, drag, and release operation. It is then up to the user to find a target that, hopefully, will receive the object(s) being dragged. Additionally, the user may not be aware if the desired drop operation is supported or what source objects can be selected for dragging. The end result can be a very unproductive and frustrating experience.

WAI-ARIA introduces two new Drag and Drop properties that aide Web application authors with the drag and drop process, called aria-grabbed and aria-dropeffect. The property aria-grabbed is applied to the source(s) being dragged, while aria-dropeffect is applied to the target(s). Use of these properties--combined with best practices for enabling the user to select the appropriate drag operations and for assigning appropriate keyboard operations for dragging and dropping--will vastly improve the accessibility of drag and drop functionality. The following steps will guide you through the process.

  1. Identify draggable objects

    Set the initial aria-grabbed state of all draggable interface objects. Roles that typically support drag and drop operations are listitem and treeitem. The default state for all objects is assumed to be undefined, meaning that they are not draggable. For objects that may be dragged, set the aria-grabbed state to "false". This will allow assistive technologies to indicate which objects are draggable and potentially facilitate in choosing the objects to grab.

    Objects that can be dragged need to have a determinable role. HTML tags such as <div> and <span> provide no semantics, unlike <select>, and would require you to set the WAI-ARIA role attribute.

    This step clearly marks elements that can be "grabbed" for drag-and-drop operation. Assistive technologies, such as screen readers or alternate input devices, can help the user move focus directly to the grab-supporting objects without having to navigate through all the elements and to guess which could be ready to initiate a drag operation. Although not necessary, authors or intermediaries could use CSS to highlight those elements that may be grabbed. At this point, qualified drop targets cannot be determined as they are determined based on the objects being dragged--which have not yet been selected.

    All grabbable objects must be navigable using the keyboard.

  2. Allow the user to initiate the appropriate drag operation using the keyboard

    The author must provide a keyboard accessible way of selecting one or more elements to drag. It is recommended that the space bar be used for selection. It is further recommended that Shift+Space be used to select multiple objects and define a contiguous set; and that control+space be used to define a noncontiguous set. As each object is selected, its aria-grabbed property must be set to "true", giving the ATs references as to what has been grabbed. It is recommended that Control+M be supported to indicate that all objects have been selected for drag.

    Selection of the objects to be dragged may differ depending on their type. For example, a list of emails might be selected one at a time or many at a time in contiguous or non-contiguous manner using the Space key as indicated above. However, text in a document might better be selected by positioning the cursor at the beginning of a word and holding down the Control key while using the right and left arrow keys to mark the letters you wish to move.

  3. Mark the drop targets

    When the user has completed selecting source objects to drag, you must indicate which targets may receive them by setting the aria-dropeffect properties on those targets. This will indicate to the assistive technology that all objects have been grabbed as well as what targets are capable of receiving the drop.

    When using a mouse, users click, hold the mouse button, and drag the mouse when moving the selected objects, and, by implication, are no longer selecting them. With respect to keyboard users, the previous section, Item 2, "Allow the user to initiate the appropriate drag operation using the keyboard", recommends using Control+M to indicate the end of the selection phase.

    * copy:
    A duplicate of the source object will be dropped onto the target.
    * move:
    The source object will be removed from its original location and dropped onto the target.
    * link:
    A reference or short cut to the dragged object will be created in the target object.
    * execute:
    A function supported by the drop target is executed, using the drag source as an input.
    * popup:
    The author must provide a popup menu or dialog to allow the user to choose one of the drag operations (copy, move, reference) and any other drag functionality, such as drag cancel.
    * none:
    no drop operation is supported. This is the default for all objects.

    Example:

    <div role="treeitem" aria-dropeffect="copy move popup">

    CSS may also be used to highlight the targets to show sighted users which objects can receive a drop of the grabbed source(s). Any object without an aria-dropeffect property set will have an assumed aria-dropeffect value of "none." Any object with an aria-dropeffect value of "none" is ignored by ATs in the drop operation.

  4. Implement keyboard functionality to assist the user and AT with executing the drop.

    After all objects have been grabbed, the author should provide standard keyboard accessible navigation (such as through tabbing) to enable the user to navigate to the desired drop target. To achieve this, you may optionally support Shift+F10 to invoke a single select list of possible drop targets from which the user may choose a single drop target that, when selected, would move focus to that drop target. Otherwise, you must provide a keyboard accessible way (through tabbing and arrowing) to allow the user to navigate to the drop target. The user's point of regard should be clearly visible during this navigation.

    When the user arrives at the drop target the author should provide a keyboard accessible way to drop the selected object(s) onto the target. Control+M should be used to provide the most intuitive type of drop, either copy, move, or a shortcut. In the case of only one drop operation available, the Control+M should be used to drop the selected object(s) onto the target.

    If drop target supports additional drop operations, then the author should provide a WAI-ARIA-enabled pop-up menu from which the user can choose supported operations from the list. A recommended way to invoke this menu is to use the Shift+Control+M key sequence when focus is on the drop target. Furthermore, the aria-dropeffect property should include "popup" in its list of values to indicate that a keyboard accessible menu is provided. After the user has selected an action from the pop-up menu, the menu must close, with focus returning to the drop target. If the user does not choose an action and instead presses the Escape key, the application must dismiss the menu, returning focus to the drop target.

  5. Cancelling a drag operation

    Users can cancel the entire drag operation at any time, with one exception, by pressing the Escape key. The one exception is when the drop operations pop-up menu is displayed (see previous step four above). In this case, Escape simply dismisses the pop-up, and a second Escape keystroke is needed to cancel the drag operation. When the drag operation is so cancelled, all aria-dropeffect properties are set to "none", all grabbable objects' aria-grabbed properties are set to "false", and keyboard focus returns to the last grabbed source object.

  6. Clean-up after drag/drop

    Once the drop has occurred, you should clean up the DOM as you would do for drag-and-drop operation. This should include setting:

    • All aria-dropeffect properties to "none" or remove them altogether.
    • All aria-grabbed of draggable objects to "false".
    • All objects that are not grabbable must either omit the aria-grabbed property or have an aria-grabbed property set to "undefined."
    • Focus on the appropriate DOM element, and its role must also be determinable.

    Other methods of performing the same operation as drag-and-drop may be the best way to meet the accessibility requirements. As an example, when moving a mail message from the inbox to another folder, a list of those folders could be presented in a select list as an alternative to drag-and-drop.

  7. Document non-recommended keyboard navigation

    If the author must use alternatives to the keyboard navigation recommended here, it should be documented on the page.

States and Properties, and Assistive Technologies

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Assistive Technologies (AT) access WAI-ARIA state and properties via a platform accessibility API. An example of such an API is Linux's AT-SPI. The user agent is responsible for publishing WAI-ARIA roles, states, and properties and relevant changes via the accessibility API. For more information, see the Core Accessibility API Mappings [[CORE-AAM]].

With respect to desktop applications, the interaction between the platform accessibility API and an AT is bidirectional. The application sends information to the AT using the accessibility API, and the AT can request a change in the accessible state of an application through the same accessibility API. However, with respect to ARIA 1.0, the flow of information is one way only from WAI-ARIA to the accessibility API. There is no provision, currently, to go the other way. An AT cannot use an accessibility API to alter any WAI-ARIA information in the DOM.

The reason is that there is no consistent cross-browser implementation of a mutation event that web applications can rely on to detect when a WAI-ARIA state or property has changed. Web applications use WAI-ARIA information for rendering their components. For example, if the web application includes a DHTML checkbox as part of its interface, then the web app renders the visual appearance of the checkbox based on its aria-checked state. If an outside agent were to change the state of that checkbox without the web app receiving any notification, then the checked state of the checkbox is no longer in agreement with its visual appearance. It is likely that the behaviour of the web app will suffer.

W3C is investigating device-independent interfaces to allow web applications to receive notification of changes to WAI-ARIA states and properties. When this is available, WAI-ARIA will be bidirectional with respect to the platform accessibility API, allowing Assistive Technologies to alter WAI-ARIA states and properties. Even so, the set of states and properties that an Assistive Technology is likely to change is limited to the following:

The following States and Properties are unlikely to be manipulated by an assistive technology: An AT would need to have greater understanding of the application and the results could be adverse.

Reusable Component Libraries

This section has not been updated since it was integrated from APG version 1.0 -- an APG taskforce review is pending.

Rich internet applications are complex to author. To save time, it is often faster to use existing widget libraries that implement WAI-ARIA and that have already gone through:

Some publicly available UI component libraries have already implemented WAI-ARIA. Authors can reuse such libraries to start developing accessible rich internet applications.

Appendices

Background on WAI-ARIA

This section has not been updated since it was integrated from the ARIA 1.0 Primer -- an APG taskforce review is pending.

According to the SecuritySpace Technology Penetration Report, more than 55% of all Web sites today contain JavaScript, dramatically affecting the ability for persons with disabilities to access Web content. New Rich Internet Applications (RIAs) render custom widgets, modeling rich desktop components to perform UI updates without having to reload the entire page - much like a graphical user interface (GUI). Legacy GUI accessibility frameworks address these issues through a comprehensive accessibility application programming interface (API) and infrastructure to foster interoperability with assistive technologies. These APIs constitute a contract between applications and assistive technologies, such as screen readers, to enable them to access rich dynamic content with the appropriate semantics needed to produce a usable alternative. No such contract exists between modern RIAs and assistive technologies, creating an accessibility gap for persons with disabilities.

Unfortunately, HTML and other markup languages do not provide adequate support for accessible dynamic content. Until now, the W3C WAI has discouraged the use of JavaScript per [[WAI-WEBCONTENT]], Checkpoint 6.1). A number of W3C initiatives underway address this problem using a declarative markup approach. This primer describes a means to bridge the interoperability problem with assistive technologies now by incorporating the appropriate metadata into current HTML and XHTML markup to support today's accessibility APIs. Moreover, the primer provides web developers with a conceptual understanding of WAI-ARIA as a prelude to using the [[WAI-ARIA]]. WAI-ARIA brings advanced accessibility features of the desktop to the web through the creation of cross-cutting technologies that (X)HTML authors can incorporate in their markup. WAI-ARIA defines roles, states, and properties, where those roles reflect standard GUI elements that are recognized by accessility Application Programming Interfaces (APIs). These metadata that describes these GUI widgets and document structures aides assistive technology vendors in providing accessible, usable solutions. The W3C WAI PF working group is working with User Agent manufacturers, assistive technology vendors, and accessibility tool providers, to ensure an end-to-end working solution.

For an introduction to WAI-ARIA, see the Accessible Rich Internet Applications Suite (WAI-ARIA) Overview. The WAI-ARIA Primer is part of a set of resources that support the WAI-ARIA specification. The Primer provides a basic introduction to the concepts behind and reason for WAI-ARIA, and the WAI-ARIA Authoring Practices describe recommended usage patterns for Web content developers. The WAI-ARIA Suite fills gaps identified by the [[WAI-ARIA-ROADMAP]]. These documents serve as important places of clarification where topics appear to be unclear.

The Problem

Aspects of traditional Hypertext Markup Language (HTML) make accessible support of dynamic content difficult:

  1. Accessibility of dynamic content relies on abstracting semantics from both content and presentational information. Extracting semantic cues from current HTML content is typically unreliable as the cues are limited to tag elements names.
  2. While HTML allows content to be repurposed for presentational formatting, it lacks the ability to attach meaningful metadata about document structure and to convey semantic information. A common example of this is content formatted with tables rather than style sheets.
  3. When combined with script and cascading style sheets (CSS), HTML can be repurposed to create dynamic custom components without providing a means to convey semantic information to native accessibility architectures designed to support dynamic graphical user interface (GUI) content.
  4. Custom components built from common HTML elements often are not keyboard accessible.

Authors of JavaScript-generated content do not want to limit themselves to using standard tag elements that define the actual user interface element such as tables, ordered lists, etc. Rather, they make extensive use of elements such as DIV tags in which they dynamically apply a user interface (UI) through the use of style sheets and dynamic content changes. HTML DIV tags provide no semantic information. For example, authors may define a DIV as the start of a pop-up menu or even an ordered list. However, no HTML mechanism exists to:

  • Identify the role of the DIV as a pop-up menu
  • Alert assistive technology when these elements have focus
  • Convey accessibility property information, such as whether the pop-up menu is collapsed or expanded
  • Define what actions can be formed on the element other than through a device-dependent means through the event handler type (onmouseover, onclick, etc.)

In short, JavaScript needs an accessibility architecture to write to such that a solution can be mapped to the accessibility frameworks on the native platform by the user agent.

The following diagram illustrates a typical document object model (DOM) node in a Model-View-Controller architecture. Accessibility information surfaced to assitive technologies is provided only by the HTML element's tag name, with only the accessibility attributes that tag can provide.

shows that on the node, data, or the "Model", which should include semantic information, is separated from the user interface presentation, the "View." Here, the document element is managed by the user agent based on the default behavior of the element. The user agent's default behavior at the document element forms the controller.

Accessibility infomation mapped to a DOM element in the Document Object Model
Accessibility Interoperability at a DOM Node without JavaScript

The box between the DOM node and the assistive technology contains the contract provided by the user agent to the assistive technology. This data includes typical accessibility information found in the accessibility API for many accessible platforms for GUIs (role, state, caret, selection, text, hypertext, name description, parent/child information, parent/child information, and relations). For HTML and other W3C markup, the accessibility information provided solely depends upon what the element's tag name and any accessibility attributes that map to that tag provides. For example, the accessible role of a table is table. The author provides an accessible description by assigning a title attribute.

In contrast, with JavaScript, user actions can trigger updates in the data and presentation, but the default accessibility information available in the element tags is no longer valid.

DOM Element with JavaScript controller
Accessibility Interoperability at a DOM Node with JavaScript

shows the same DOM node provided in Figure 1.0 but with JavaScript acting as the new controller. JavaScript overrides the default user agent behavior at the DOM node. It manipulates the data, content, and style in response to events caused by user interaction to produce custom widgets. In this situation, the default accessibility information is no longer valid and, therefore, the contract is now invalid. Figure 2.0 shows the contract with asterisks in front of role, state, actions, value, event changes, and relations. These asterisks represent potential accessibility errors and gaps in the base markup. These gaps result from the author's inability to provide the new semantic data needed to support the contract.

Requirements

Any solution to facilitate the creation of accessible rich Internet applications (RIAs) must:

Allow for discovery of custom UI components through the use of Semantic Web technologies
Web ontologies allow for storage of semantic information about objects and how they relate to others in the ontology.
Support today's accessibility architectures
Accessibility architecture today is centered around object technology. Each object in an application or document exposes its accessible properties to an assistive technology.
Allow for separation of content and presentation
Dynamic content authors must be able to store the accessible meta data in the document independent of how it is rendered.
Allow for passive monitoring of the application by an assistive technology
Assistive technology vendors should not be required to poll an application for changes in accessibility information.
Leverage new W3C efforts to solve the problem
This problem needs to be solved quickly. A number of efforts are underway, such that minimal changes may be required to bring them to the level needed.
Be light weight
The solution needs to be light-weight in order to promote adoption by Web authors.
Scaleable
The solution needs to be scalable; it must make simple things easy while making complex things possible.
Internationalizable
Like other Web solutions, our solutions must be internationalizable.
Guarantee user agent support up front
User agent manufacturers must be involved up front to ensure support for the solution when the specification is complete.
Involve assistive technology vendors up front
To ensure interoperability, assistive technology vendors need to be involved from day one. The effort must leverage support by AT vendors to ensure that a total solution is available when the specification is complete.
Produce Developer Guidelines during the process
This is a critical mistake made by people creating a new accessibility model. Developers must be engaged early on so that they can contribute feedback and start producing workable solutions early.

Solution

What is clear from the problem statement is that developers of dynamic web content cannot provide the appropriate accessibility information in the markup to support the accessibility APIs on the target platform. This problem is not limited to HTML. It extends to other markup, including Scaleable Vector Graphics [SVG]. This primer addresses the problem for web content delivered to desktop browsers and introduces you to common extensions to both HTML and XHTML called [[WAI-ARIA]]. The goal is to make these standard features in HTML 5.

HTML Accessibility API Support Analysis

Using as a template for addressing the problem and U.S. Section 508 accessibility standards, Table 1.0 illustrates gaps in the infrastructure and identifies W3C standards that should be used to address the problem. In the right column, table cells that are empty or that indicate a limitation represent accessibility gaps in HTML and XHTML.

Table 1.0 Platform Gap Analysis for Accessible Dynamic Web Content for HTML and XHTML
Required Components Who does what today? (HTML)
Events:  
FocusChange DOM 2, 3 events
Activation User Agent API
Caret Change User Agent API
Value Change  
State Change  
Selection Change User Agent API
Mutation DOM Events
Accessible Actions:  
Event Handler functional information to label the actions  
Access to the available event handlers for enumerating the actions  
State Information:  
Role Information: Limited to standard HTML tag names. (Mix Content/presentation)
Relationships: Parent/child Limited DOM (affected by style) (Mix Content/presentation)
Relationships: (Label, MemberOf - Group, ControllerFor) Limited to HTML (Title, alt, label)
Text Core DOM from parsed HTML
Content selection: Browser-dependent (incomplete)
Font/Font Style Information: Can set but can't get final format
Description/Help: Limited to HTML 4.0 - Alt Text, title text
Accessible value: Limited to form elements
Coordinates (Bounding rectangle, etc.): User Agents. platform accessibility API
Accessible Name:  
Respond Desktop Font/Color Changes: Partial (conflicts with CSS and JavaScript)
Device independent navigation:  
Accessibility API Mapping: Partial - User Agents
Provide focus to all active elements (important for equivalent keyboard access on desktops) Limited to forms and anchors

Filling the Gaps for Content Delivered to Desktop Browsers

This section has not been updated since it was integrated from the ARIA 1.0 Primer -- an APG taskforce review is pending.

At this time,W3C WAI Protocols and Formats working group's primary focus is on extensions to HTML 4.01 and XHTML 1.X by extending the host language to include WAI-ARIA with a migration path to HTML 5. This will require the creation of new hybrid document type definitions (DTDs) that incorporate the extensions. This work will be in the [[WAI-ARIA]] specification. WAI-ARIA will constitute extensions to fill most of the gaps needed to support accessibility API infrastructures and dynamic (X)HTML content. The comprehensive gap analysis of (X)HTML, used to form WAI-ARIA is found in Table 1.0 and how WAI-ARIA fills those gaps. In the future we hope to incorporate WAI-ARIA into many host languages to improve their accessibility. The critical extensions needed to make accessible dynamic Web content accessible, through rich interoperability with assistive technologies, are summarized here:

States, and Property attributes - This is the set of attribute modifications to (X)HTML necessary to provide full keyboard focus and states and properties that may be mapped directly or indirectly to platform accessibility APIs to ensure full interoperability with assistive technologies for WAI-ARIA.

Role attribute - The role attribute, borrowed from the, [[ROLE-ATTRIBUTE]], allows the author to annotate host languages with machine-extractable semantic information about the purpose of an element. It is targeted for accessibility, device adaptation, server-side processing, and complex data description. WAI-ARIA uses the role attribute to provides the role information, in to an assistive technology.

Role document landmark values - These values, borrowed from the [[ROLE-ATTRIBUTE]] provides a standard set of role attribute values designed to define pertinent parts of a document (landmarks) for the purpose of accessibility. User agents may incorporate device equivalents, such as key mappings in the case of a desktop user agent, to navigate to these sections of a document.

Taxonomy of WAI-ARIA role values - The necessary core roles found in Accessibility API sets for Windows and Linux as well as roles representative of document structure, such as banner or treegrid. Use of document structure is necessary for assistive technologies to navigate complex documents and to know when they have entered active areas of a Web page such as in the case of a dynamic scripted Web application. The taxonomy is designed to help user agents or authoring tools determine what properties a given role supports and to assist with accessibility API mapping of these properties. The taxonomy will is like a class hierarchy used to convey semantics and structure and includes knowledge about each role. At this time, that taxonomy is modeled using [[RDF-CONCEPTS]] and [[OWL-FEATURES]].

In short, WAI-ARIA will be used to fix the dynamic accessibility of scripted Web content, in particular the use of JavaScript with (X)HTML markup. They are meant to be cross-cutting and should apply to other markup like SVG. Less critical for (X)HTML but helpful for accessibility will be the descriptive extensions to XML events and the new [[XHTML Access]]. Web Content Accessibility Guidelines 2.0 calls for the WAI-ARIA properties in guideline 4.1 Maximize compatibility with current and future agents, including assistive technologies (roles, states, properties, and values) and section guideline 1.3 Create content that can be presented in different ways (for example spoken aloud, simpler layout, etc.) without losing information or structure (relationships).

The next section describes how the specifications are used together as well as how they will be implemented in HTML 4.

Use of New Provisions for Keyboard Focus and Semantics to Support Platform Accessibility APIs

Adaptive technologies, which need to provide alternative access to complex user interfaces authored via HTML, are often left guessing at the semantics behind specific portions of HTML document. As an example, an XHTML document might use a certain HTML construct, such as a collection of DIV tags, to create navigation bars, a site-navigation menu, and other GUI-like user interface widgets. To fix the problem, we incorporate the role attribute, assign the accessible state properties, and give the object focus using the new TABINDEX feature. Addition of this information helps authors to provide the necessary information to enable the user agent to support the accessibility API accessed by the adaptive technology.

Provision of the Role Attribute: "What is the Object?"

Each platform accessibility API has the notion of a "role" for a GUI object. This is the case for [[JAPI]], [[MSAA]]], [[AXAPI]], and the [[ATK]], or [[UI-AUTOMATION]] (called content type in UI Automation). The WAI-ARIA specifications are based on XHTML 1.X and include the role attribute. The "role" attribute takes a qname, enabling authors to reference the role attribute from the WAI-ARIA Roles. In the following example, we use qname to reference the menu role in the WAI-ARIA specification.

Example: Use of WAI-ARIA to incorporate role information into XHTML 1.x

<?xml version="1.1" encoding="us-ascii"?>
<!DOCTYPE html PUBLIC "Accessible Adaptive Applications//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"
>
    <body>
        <div role="menu">
            File
        </div>
    </body>
</html>

WAI used RDF/OWL to model our taxonomy for WAI-ARIA. In fact, if a host language sought to use namespaces or qnames, they could do so to reference the WAI-ARIA role taxonomy. The WAI-ARIA role taxonomy could be used by authoring tool developers to ensure that states and properties assigned to a given role are accurate.

Provision of the Accessibility State Information: "What meaningful properties does this object have at this time?"

Since this is dynamic content, the state of these new repurposed objects will change. The WAI-ARIA specification shall provide the common accessible properties needed to support the accessible state or property information provided by the platform accessibility API defined previously. This specification was created based on an analysis of the accessibility properties defined in MSAA and ATK. The following example extends the previous approach by adding the aria-haspopup accessibility property.

Example: Use of WAI-ARIA to incorporate accessible state information information into XHTML 1.x

<?xml version="1.1" encoding="us-ascii"?>
<!DOCTYPE html PUBLIC "Accessible Adaptive Applications//EN" 
    http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">



>
        <body>
            <div role="menu" aria-haspopup="true">
                File
        </div>         
    </body>
</html>

A Windows user agent may now map this property to the Microsoft Active Accessibility state of STATE_SYSTEM_HASPOPUP. Adding or removing this state would result in the Windows user agent sending an EVENT_OBJECT_STATECHANGE event to the assistive technology. The task of the JavaScript page author would be to maintain this state attribute, which can easily be done through the use of Document Object Model calls.

Provision of the Keyboard or Input Focus: "What object am I working on?"

Virtually all adaptive technology solutions, such as screen readers and onscreen keyboards, must know which object currently has focus. For example, an author might want to insert text into the current object with focus or to announce information about the object that has focus. With today's HTML 4.01 and XHTML 1.x, script authors can only provide focus to form and anchor elements yet the Document Object Model Specification allows all elements to receive events including keyboard events. This means that HTML, by design prohibits script authors from making all HTML elements keyboard accessible. This single problem effects usability of Web pages where one gains access to elements by using the Tab key on desktop browsers. This slow, unproductive, approach makes portal navigation difficult because all active elements must be tabbed through to put focus on an active element in the last portlet in a document. To solve this problem in XHTML 1.x, we are incorporating a feature in Firefox and Internet Explorer to define the tabindex for -1. This allows a script author to give an element focus without placing it in the tab order: The following table describes these changes that will be incorporated into the new Accessible Adaptive Application specification.

Accessible Adaptive Application Changes to Support Use of tabindex to give Element Focus
tabindex attribute Focusable with mouse or JavaScript via element.focus() Tab navigable
not present Follows default behavior of element (yes for form controls, links, etc.) Follows default behavior of element
Negative, e.g. tabindex="-1" Yes No, author must focus it with element.focus() as a result of arrow or other key press
Zero, e.g. tabindex="0" Yes In tab order relative to element's position in document
Positive, e.g. tabindex="33" Yes Tabindex value directly specifies where this element is positioned in the tab order. These elements will be positioned in the tab order before elements that have tabindex="0" or that are naturally included in the tab order (form elements and links)

The following example shows the introduction of TABINDEX to provide focus to a DIV having the new accessibility meta data:

Example: Use of tabindex to give non-form and anchor elements focus in XHTML 1.x

<?xml version="1.1" encoding="us-ascii"?>
   <!DOCTYPE html PUBLIC "Accessible Adaptive Applications//EN" 
    http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">



>
    <body>
        <div role="menu" aria-haspopup="true" tabindex=-1>
            File
        </div>
    </body>
</html>

Supporting WAI-ARIA in XHTML and HTML 4.01

Unlike XHTML, HTML 4.01 is non-extensible in that it is not possible to extend HTML 4 through the use of namespaces. That said, members of the working group have worked with the HTML working group to agree on a vehicle that does not use namespaces, which at this time is supported by XHTML and HTML which will be supported in HTML 5 when it becomes recommendation. Firefox 3 is leading the way to implement this, and other browser manufacturers are working to support it as well. The technique allows all role values specified in WAI-ARIA (including those specified by the XHTML Role attribute module) to be specified without a namespace prefix. Additionally, WAI-ARIA states and properties shall be represented as aria- followed by the concatenated WAI-ARIA state or property.

Example: Browser supported HTML technique for the tabindex example in section 5.1.3


<html lang="en">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
  </head>
    <body>
        <div role="menu" aria-haspopup="true" tabindex=-1>
            File
        </div>
    </body>
</html>

In order to validate these extended attributes for HTML and XHTML the WAI-PF working group will investigate the creation of an enhanced schema or DTD for each host language.

Use of XHTML Role Landmarks to Improve Document Navigation

In addition to the common roles which will reside in WAI-ARIA Roles, both XHTML 2.0, and the XHTML Role attribute module ([[ROLE-ATTRIBUTE]], Section 4) defines a collection of common role, regional, landmarks that define pertinent parts of a document for the purpose of accessibility. User agents may incorporate device equivalents, such as key mappings in the case of a desktop user agent, to navigate to these sections of a document independent of the Web site. The addition of these semantics allows the user agent to provide standardized navigation to common document sections. This is especially important for portals to improve the usability. These may be used as attributes in XHTML 1.x by applying them to sections of the document as shown in this example. Note: since these roles are a part of XHTML they do not need to be namespace qualified.

Example: Use of XHTML navigation role to define a landmark for the navigation section in an XHTML 1.X document

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">    
<html xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>    
  <title>application/xhtml+xml: Navigation Roles Example 1</title>        
  <link rel="stylesheet" href="css/nav1_xhtml.css"  type="text/css" ></link>    
  <script type="text/javascript" src="../js/globals.js"></script>    
  <script type="text/javascript" src="../js/widgets_xhtml.js"></script>  <link rel="icon" href="http://www.cites.uiuc.edu/favicon.ico" type="image/x-icon" />    
  <link rel="shortcut icon" href="http://www.cites.uiuc.edu/favicon.ico" type="image/x-icon" />    
</head>    
<body onload="widgets.init()">
.
.
.    
<div id="leftnav">         
<h2 class="nav" id="leftnav_label">Career Center Services</h2>         
 <ul title="Career Center Services" role="navigation" aria-labelledby="leftnav_label">        
   <li><a href="http://www.uiuc.edu/">Career Home</a></li>  
   <li><a href="http://www.uiuc.edu/">Career Counseling</a></li>        
   <li><a href="http://www.uiuc.edu/">Pre-Health Advising</a></li>        
   <li><a href="http://www.uiuc.edu/">Services</a></li>        
   <li><a href="http://www.uiuc.edu/">Workshops</a></li>        
   <li><a href="http://www.uiuc.edu/">Resource Center</a></li>        
   <li><a href="http://www.uiuc.edu/">Question Board/FAQ</a></li>  
 </ul>

...

</body>

The example above was taken from the header from the Career Center Web page at the University of Illinois at Urbana-Champaign. Students from this university, under Jon Gunderson's guidance created Accessibility extensions for Mozilla/Firefox, in part, to allow a page author or user to view a list of navigation landmarks. This tool, shown in , lists the navigation sections on the page. Keyboard navigation of the list of navigation bars causes the corresponding document section to be highlighted. The title for each navigation region displays in the list.

Table of Contents from Landmarks
Table of Contents generated from navigation landmarks in the header

shows the accessibility extensions for Mozilla/Firefox from the University of Illinois at Urbana-Champaign to render the document landmarks. This picture shows the Firefox browser rendering the University of Illinois Career Career Center home page. In this example. The "List of Navigation Bars" viewer is shown, launched from the extension on the toolbar. The viewer shows that the secondary "Career Center Services" is selected resulting in that section of the document being highlighted in yellow. The Navigation Bar Lists Viewer lists the following list of titles corresponding to the navigation sections:

  • Career Counseling Resources
  • Resources by Audience
  • Career Center Services
  • Quick Links

WAI-ARIA Role Taxonomy - Extensible Semantic Role Model, using RDF/OWL

The WAI-ARIA role taxonomy was modeled using semantic web technology, in the form of [[RDF-CONCEPTS]] and the [[OWL-FEATURES]], as a vehicle to define a knowledge-based class hierarchy for roles. This model shows what states and properties are supported, by each role in the taxonomy. The role in the class hierarchy inherits properties from its ancestors and defines its own properties. Where applicable, semantic web technology is used to define related concepts within other namespaces. This information is critical in determining how to choose a role and how to interact with it. The role taxonomy uses RDF as a way for using data to describe data and provides a W3C standards-based approach to represent this information.

Sample Semantic Map for Taxonomy
Example, Partial RDF Map for a possible ButtonUndo role as an extended role to WAI-ARIA

shows a basic RDF mapping that defines a set of terms and relationships defining an object. At the center is a Widget object that defines common states and properties for all GUI widgets. The Button object extends Widget and inherits defined accessibility properties from the superclass Widget. It also defines a relatedConcept property to a Link object. The ButtonUndo role extends Button. It has a relatedConcept of an HTML input object. ButtonUndo will introduce Dublin Core meta data such as the description of the object. The terms relatedConcept and requiredState are terms that will be defined as part of the corresponding RDF schema. Each role instance will represent standard Roles found in the platform accessibility APIs of platforms like Windows and Gnome as well as content structure. These roles will form the taxonomy. Although host language browser implementations may reference WAI-ARIA roles without namespaces, the RDF representation for a given role may be referenced using a qname from a Host XML markup language. This examples shows an XHTML reference to a grid role in the RDF representation of the WAI-ARIA taxonomy:

<div role="grid"> whereby grid expands to: http://www.w3.org/2005/01/wai-rdf/GUIRoleTaxonomy#grid in the button markup.

The power of this design is that it enables a web authoring tool to go back into the corresponding RDF/OWL markup and determine what properties it supports for Accessibility API mapping. Additional, middleware solutions can now make intelligent transformations of Web Content by processing the semantics behind rich browser and rich structured frameworks to adapt accessible solutions for a broader user base. Our immediate goal is to fix the accessibility problem with scripted Web content. Assistive technologies will use the standard roles to determine how to render most content.

Interoperability Example: Grid Role

To understand the power of this approach, consider the case of a Grid Role, analogous to a table. shows a DHTML example using XHTML, JavaScript, and CSS to produce a GUI-like application. This example developed in IBM shows a notebook tab with a data grid that behaves like a traditional desktop GUI. The user uses arrow keys to navigates the data grid and among the page tabs. Using the Tab key, a user navigates between the notebook tab, the edit fields, buttons, and the data grid.

DHTML example of GUI-like notebook tab with a data drid
DHTML Example

Accessible role and state meta data from the WAI-WAI-ARIA Roles, States, and Properties specification, are added as attributes to each of the XHTML elements repurposed as GUI widgets dynamically. The user agent, in this case Firefox, maps this information to the platform accessibility API. shows the Microsoft Active Accessibility rendering of the new accessibility markup provided on the DataGrid page tab which has focus.

MSAA Inspect Tool diagnostics for Notebook page tab
Microsoft Inspect Tool rendering of the page tab DataGrid

show a Microsoft Inspect 32 rendering of the DataGrid Page page tab in Figure 5.0. Inspect32 provides Microsoft Active Accessibility information; here it shows the accessible role of "page tab" and accessible state information of focused, focusable, and linked. There are no page tab elements in XHTML. Here, an XHTML DIV element is repurposed by a JavaScript controller to look like a notebook tab. It is now able to receive focus, unlike in standard XHTML 1.X, and it does so without requiring tabbing. With these specifications, the script author can now add the accessibility properties to support platform accessibility API. Accessible state properties for the DataGrid page tab are shown as focused, focusable, and linked. Unlike a GUI application, authors need only enable their applications once for multiple operating system platforms.

Beyond scripted Web content, the working group intends to extend the use of roles to enable other user cases. These may include:

  • Structured Textual Markup - enhancing structure of the markup of a document, including Data Tables , or translating the structure of an XML document to a markup structure that user agents are used to dealing with (e.g. myXML to XHTML) Binding sections of a document to a common role. This allows for different navigation techniques though a document
  • Knowledge representation of Web content - As a secondary benefit, roles improve compatibility with Knowledge-Based Services and the Semantic Web. By integrating accessibility and the semantic Web, accessibility can be moved forward, paving the way for customized accessible searches and intelligent user agents with additional applications.
  • Adding concepts in the type of content for adaptation to the user scenario - The more that is understood about content, the better it can be adapted for the end user. For example:
    1. If it is known that a page hyperlink has the role of taking the user to the site's home page, then that knowledge can be used to create enhanced accessibility in different ways in many different scenarios, such as icons or access keys.
    2. If it is known that a text box is for the user email address, then the user agent can support users filling in the form by labeling it with an icon or symbol, automatically validating it, or even form filling.
    3. If it is known that a paragraph is complex, then a simple equivalent can be shown in its place
    4. If a word is ambiguous, then a role of a concept can be given, providing clarity An example of this may be : <span role="role:nonliteral" aria:hasAlternate="no">

Accessibility Events and Event Handling

Interoperability between applications and assistive technologies requires event notification for accessibility. The events will be fired via the user agent. The accessible value and state property changes will be generated in response to changes in the DOM attributes as defined by the WCAG 1.0 AAA specification. User agents supporting the platform accessibility API, will support event notification such as the state change or value change events.

HTML 5 - A Look Ahead

HTML 5 and the "serialized" XHTML version of HTML 5 are years away from standardization. We have preliminary consensus to add the WAI-ARIA states and properties, role, and tabindex changes needed for WAI-ARIA in HTML 5 as demonstrated in section 5.1.4. This is subject to change between now and when the specification goes to recommendation. In HTML 5, we will see many more standard controls that developers may choose to use and that should be used in preference to WAI-ARIA features. We shall continue to promote WAI-ARIA's use and adoption in industry to ensure that there continues to be the ability to provide support accessibility of new types of controls. A number of gaps remain, such as named event handlers and enhancements for access key, that we need to address. This work is in progress.

Building Accessible Applications with WAI-ARIA

This section has not been updated since it was integrated from the ARIA 1.0 Primer -- an APG taskforce review is pending.

This section provides a brief introduction to the process of making applications accessible using WAI-ARIA. The choice and usage of roles can be complex and context dependent. It is beyond the scope of this document to explain implementations for all the possible WAI-ARIA use cases. WAI-ARIA Authoring Practices provides detailed guidance on WAI-ARIA implementation methodology as well as references to sample code.

First steps to making an application accessible:

  1. Each element or widget has correct and complete semantics that fully describe its behavior (using element names or roles);
  2. The relationships between elements and groups are defined;
  3. States, properties, and container relationships are valid for each element's behavior and are accessible via the [[dom]] and the platform accessibility API; and
  4. Keyboard focus should be maintained for the duration of the user's interaction with the application.
  5. All interactive components should be keyboard operable.

WAI-ARIA provides authors with the means to make the different elements in a web application semantically rich. User agents use the role semantics to understand how to handle each element. Roles convey additional information that the assistive technologies need to anticipate the behavior of the elements inside the application such as how to present the corresponding WAI-ARIA states and properties to the user. The user agent will use the accessibility semantics from the host language and WAI-ARIA accessibility semantics (which may augment or override those of the host language) and present them to assistive technologies through the Document Object Model or the platform accessibility API. The user agent will create an accessible representation of each element in the web page, and will use the appropriate accessibility API to notify assistive technologies of changes to the semantics of those elements.

The following steps are recommended when WAI-ARIA is applied to content:

  1. Use native markup when possible.

    Use the semantic elements that are defined in the host markup language. For example, with HTML or XHTML, it is better to use the native checkbox than to use a div element with role checkbox as these should already be accessible through your browser. There may also be cases where WAI-ARIA can augment an existing element in the host language. For example, a grid and gridcell elements can reuse the functionality of a table when overlaying it. WAI-ARIA roles, states, and properties are best used when the markup language does not support all the semantics required. When a role attribute is added to an element, the semantics and behavior of the element are augmented or overridden by the role behavior.

  2. Apply the appropriate roles.

    Set roles to make sure elements behave predictably and correctly describe the behavior of each element within the application, unless element behaviors are fully described by the native markup language. Roles for interactive elements should support all the attributes that the element could use. Once a role attribute is set it should not be changed as this may confuse the end user. This does not preclude an element being removed which has the role attribute set, but only states and properties (aria-* attributes) should be changed for a given element.

  3. Preserve semantic structure.

    Structural information is critical to providing context to persons with disabilities. Preserve DOM hierarchy within structural elements and widgets:

    • Form logical groups within user interface widgets, such as treeitem elements in a group.
    • Identify large perceivable regions and apply a landmark role to those areas. This will facilitate keyboard navigation. It will also facilitate content management by assistive technologies by providing semantics to manage how much information is rendered at a given time. The use of WAI-ARIA landmarks helps everyone, including vision-impaired users, dexterity-impaired users, and even users with cognitive or learning impairments.
    • For areas of the page that contain a group of elements that are likely to change through an Ajax application it may be specified as a live region, through the use of the aria-live attribute or it may be marked with pre-defined roles, such as log, which has assumed behavior of a live region.

  4. Build relationships.

    Look for relationships between elements, and mark them using the most appropriate property or attribute. For example, if a page contains both a search form and search results region, mark each container as a region and set the aria-controls attribute of the search form to reference the search results. See relationships in WAI-ARIA.

    Some relationships are determined automatically from the host language, like label elements associated with input elements in HTML.

  5. Set states and properties in response to events.

    Once the role for an element has been set, change states and properties as appropriate during the element's life cycle, usually in response to user input events. Only use attributes supported for the chosen role or element.

    User agents should notify assistive technologies of state changes. Conversely, assistive technologies' notification of property changes depends on the method by which assistive technologies communicate with the user agent. For example, the aria-multiline attribute (a property) is not something that changes frequently, whereas the aria-checked attribute (a state) changes frequently in response to user input.

  6. Support full, usable keyboard navigation.

    Usable keyboard navigation in a rich internet application is different from the tabbing paradigm in a static document. Rich internet applications behave more like desktop applications where the user tabs to significant widgets and uses the arrow keys to navigate within a complex widget, such as a menu or spreadsheet. The changes that WAI-ARIA introduces in keyboard navigation make this enhanced accessibility possible. Tabbing in the document should follow a logical navigation structure. Authors implementing arrow key navigation should, where possible, follow the design patterns in the WAI-ARIA Authoring Practices Guide. When using these features, it is important as always to ensure keyboard navigation is logical.

  7. Synchronize the visual interface with the accessible interface.

    This will allow the state of your UI to be perceivable to the user as well as assistive technologies. For example, the author should use the appropriate WAI-ARIA attribute on a form element that is visually styled to appear required (aria-required) or a gridcell that is visually styled to appear selected (aria-selected). Authors may choose to achieve visual synchronization of these interface elements by using a script or by using CSS attribute selectors.

Example: Building a Tree Widget

Graphic of an example tree view.

A basic tree view allows the user to select different list items and expand and collapse embedded lists. Arrow keys are used to navigate through a tree, including left/right to collapse/expand sub trees. Clicking the visible expander button with the mouse also toggles expansion. Further keyboard implementation details for tree widgets may found in the .

To make this feature accessible we need to:

  • Inform assistive technologies about the role of each element;
  • Inform assistive technologies about the relationships between tree items;
  • Give a clear keyboard focus that will not confuse users with disabilities; and
  • Expose the changing states (expanded and collapsed) of the tree items.

Following the steps below:

  1. Look at the native markup language

    Although standard list behavior is supported by the native ul and li elements in HTML, there is no element that natively supports list expansion and selection. Since there is not, we will need to use roles.

  2. Finding the right roles

    Since there is no native tree element in HTML, we need to add roles from the taxonomy that support the additional states and properties needed. The roles that support tree behavior are:

    • tree: A tree is the main container element for our tree. It is a form of a select where sub-level groups of treeitems may be collapsed and expanded.
    • treeitem: A treeitem is an option item of a tree. This is an element within a tree; sub-level groups of treeitems may be expanded or collapsed.
    • group: A group encloses a set of sub-level treeitems.

  3. Look for groups and build relationships

    Tree relationships can be made simply via the DOM and logical structure of the page. A tree element will be the main container encompassing all other elements in the tree. Each selectable item in the tree will be a treeitem.

    When a treeitem contains an embedded list of treeitems they will be all be embedded in a group. A group should be contained inside the tree item that is the parent item.

    <h1 id="treelabel">WAI-ARIA Tree Example</h1>
<ul role="tree" aria-labelledby="treelabel" aria-activedescendant="example_id" tabindex="0">
  <li role="treeitem" aria-expanded="true">Animals
    <ul role="group">
      <li role="treeitem">Birds</li>
      <li role="treeitem" aria-expanded="false">Cats
        <ul role="group">
          <li role="treeitem">Siamese</li>
          <li role="treeitem">Tabby</li>
        </ul>
      </li>
      <li role="treeitem" aria-expanded="true">Dogs
        <ul role="group">
          <li role="treeitem" aria-expanded="true">Small Breeds
            <ul role="group">
              <li role="treeitem">Chihuahua</li>
              <li role="treeitem" id="example_id">Italian Greyhound</li>
              <li role="treeitem">Japanese Chin</li>
            </ul>
          </li>
          <li role="treeitem" aria-expanded="false">Medium Breeds
            <ul role="group">
              <li role="treeitem">Beagle</li>
              <li role="treeitem">Cocker Spaniel</li>
              <li role="treeitem">Pit Bull</li>
            </ul>
          </li>
          <li role="treeitem" aria-expanded="false">Large Breeds
            <ul role="group">
              <li role="treeitem">Afghan</li>
              <li role="treeitem">Great Dane</li>
              <li role="treeitem">Mastiff</li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </li>
  <li role="treeitem" aria-expanded="true">Minerals
    <ul role="group">
      <li role="treeitem">Zinc</li>
      <li role="treeitem" aria-expanded="false">Gold
        <ul role="group">
          <li role="treeitem">Yellow Gold</li>
          <li role="treeitem">White Gold</li>
        </ul>
      </li>
      <li role="treeitem">Silver</li>
    </ul>
  </li>
  <li role="treeitem" aria-expanded="true">Vegetables
    <ul role="group">
      <li role="treeitem">Carrot</li>
      <li role="treeitem">Tomato</li>
      <li role="treeitem">Lettuce</li>
    </ul>
  </li>
</ul>

    The use of aria-expanded should mirror that which is visibly expanded on screen, so authors may wish to use CSS attribute selectors to toggle visibility or style of an item based on the value of an WAI-ARIA state or property. The following example would hide the sub-level groups of a collapsed tree node.

    [aria-expanded="false"] [role="group"] { display: none; }

    At the time of this writing, this CSS example, while technically correct, will not redraw styles properly in some browsers if the attribute's value is changed dynamically. It may be necessary to toggle a class name, or otherwise force the browser to redraw the styles properly.

    Sometimes a tree structure is not explicit via the DOM and logical structure of a page. In such cases the relationships must still be made explicit using the states and properties. In the following example, the aria-owns attribute indicates that the div with id "external_treeitem" should be considered a child of the ul element with the attribute, even though it is not a child in the DOM.

    ...
<li role="treeitem" aria-expanded="true" aria-owns="external_group">Vegetables</li>
...
<ul role="group" id="external_group">
  <li role="treeitem">Carrot</li>
  <li role="treeitem">Tomato</li>
  <li role="treeitem">Lettuce</li>
</ul>
...

    Sometimes trees (and other lists or grids) cannot be completed represented in the DOM due to performance limitations of the browser. For example, an application interface may only need to display 100 items out of a set of 100,000. Including all 100,000 items in the DOM could cause performance problems on both the client and server machines.

    If items in a managed widget are loaded, for example, via the XMLHttpRequest object, and not present in the DOM at all times, authors should use aria-level, aria-posinset and aria-setsize, and ensure that aria-owns is not required to convey membership with the widget.

    ...
<li role="treeitem" aria-level="1" aria-posinset="3" aria-expanded="true" aria-setsize="3">
  Vegetables
  <ul role="group">
    <li role="treeitem" aria-level="2" aria-posinset="6" aria-setsize="8">Carrot</li>
    <li role="treeitem" aria-level="2" aria-posinset="7" aria-setsize="8">Tomato</li>
    <li role="treeitem" aria-level="2" aria-posinset="8" aria-setsize="8">Lettuce</li>
  </ul>
<li>
...

  4. Use states and properties in response to events

    Control the behavior of the element in response to user input events such as from the keyboard and the mouse, which includes maintaining the current states and properties for that element. For example, a tree control will need to respond to click events on the expand/collapse triggers, and key events on the currently active descendant. Use device-independent events with supporting JavaScript to handle user interaction. For detailed examples of this please refer to the Design Patterns section.

Reasons for Adopting WAI-ARIA

This section has not been updated since it was integrated from the ARIA 1.0 Primer -- an APG taskforce review is pending.

By adopting WAI-ARIA, both developers of static web sites and of dynamic Internet applications can improve the usability, accessibility, and scalability of their products. Developers of static web content can continue to follow the 1999 WCAG 1.0 standards, while improving usability and accessibility through the use of WAI-ARIA landmark roles, aria-labelledby relationships, and properties like aria-invalid and aria-required that can apply to HTML form controls. In richer, dynamic content, developers create custom widgets like calendars and spreadsheets based on technologies such as Ajax and CSS; to achieve accessibility, they need to use WCAG 2.0. Previously, when delivering rich Internet applications to users, to comply with WCAG 1.0, developers resorted to providing alternative, static content. While such measures met the WCAG 1.0 requirements, people using assistive technologies were not provided the richer user experience. When tables are used for layout, rather than CSS absolute positioning, historically, they have been problematic for assistive technologies to interpret. When the WAI-ARIA role of presentation is used on such tables, the assistive technology ignores the table structure, providing a more accessible experience without requiring major recoding.

Technical Benefits

Consider a rich Internet application where developers attempt to achieve keyboard accessibility using markup language. Without WAI-ARIA, results may be keyboard accessible but not highly usable; consider a user having to press Tab thirty times to put focus on a checkbox. To achieve keyboard accessibility in HTML without WAI-ARIA, developers must code active elements either as a link or as a form element. Accordingly, this means that no additional semantics are required or provided, other than that provided by the host language. In addition, WCAG 1.0 requires that content be renderable with Cascading Style Sheets turned off in the browser. This approach creates the following general usability problems:

  • All keyboard-accessible controls must be either forms or anchors, forcing the user to tab through all focusable elements on the web page to navigate. If you need to navigate from the first link on the page to the last link on the page, that could be a very long trip and takes usability a step back.
  • Without WAI-ARIA semantics, you cannot provide contextual information to the user.
  • If you repurpose HTML elements you cannot provide the appropriate role and context information for the new widget. Lack of context is a serious usability problem. WAI-ARIA semantics results in providing contextual information to the user.
  • CSS is used for absolute positioning. If you remove that capability, usability features of widgets like pop-up menus disappear. Imagine activating the file menu and the menu showing up at the bottom of the page.

WAI-ARIA and WCAG 2.0 coding techniques are useful for developing content and applications that can scale across a variety of user agents, including those on mobile devices.

For all these reasons, adopting WAI-ARIA makes good technical as well as business sense. For a further illustration, compare how accessibility is achieved with WCAG techniques without and with WAI-ARIA, as shown in .

Editor's Note: Figure 7, described as WAI-ARIA tree widget usability comparision, refers to a resource that has not yet been found.

Usability of Tree Widget Using WAI-ARIA Semantics to Implement WCAG 2.0 Guidelines Compared to WCAG 1.0 Without WAI-ARIA

shows an "accessible" widget for a tree item, within a tree widget, using WCAG 1.0 without WAI-ARIA, which ,when supplied to a screen reader, may say "link folder Year." There is no information to indicate that the folder is closed (aria-expanded = "false"). There is no information to indicate its depth (aria-level="2"), position in the set and the set size at the level, all of which provides the user with context something sighted users may take for granted. The role is used to indicate that it is a treeitem which indicates that the item should behave and navigate with the keyboard like a tree item. A screen reader using the WAI-ARIA version might say "Closed Folder Year, Closed Folder one of two, Depth two, unchecked." Furthermore, the WAI-ARIA version can allow the tree items to be navigated with arrow keys and without requiring they be navigated as part of a global web page tabbing scheme. This is not what any user would expect of a tree widget. Finally, if you were told all widgets were links on the web page, consider how usable -- or not -- that would be.

Business Benefits

If, as described above, coding techniques to achieve accessibility compliance do not promote overall usability, then business strategists must ask "Why invest in accessibility?" With WAI-ARIA, businesses can invest in accessible development and reap benefits for all users, not just those with disabilities or using assistive technologies. Some benefits include:

  • Because WAI-ARIA is being developed through the PFWG with cooperation from browser and assistive technology vendors, accessibility and interoperability with those technologies will be easier to achieve, reducing or eliminating the need for per-browser and per-screenreader coding to achieve accessibility.
  • In addition to people with disabilities, all users benefit from WAI-ARIA because it establishes a Web-standard for keyboard interaction, easing the learning curve for users moving among applications, sites, and browsers.
  • Implementing WAI-ARIA can facilitate test automation. Test engines require semantic information about user interface elements, unique names, exposure of state, specific properties in order to run automated test scripts. WAI-ARIA provides that semantic information needed for efficient test automation.