The intent of this Success Criterion is to ensure consistent identification of functional components that appear repeatedly within a set of Web pages. A strategy that people who use screen readers use when operating a Web site is to rely heavily on their familiarity with functions that may appear on different Web pages. If identical functions have different labels on different Web pages, the site will be considerably more difficult to use. It may also be confusing and increase the cognitive load for people with cognitive limitations. Therefore, consistent labeling will help.
This consistency extends to the text alternatives. If icons or other non-text items have the same functionality, then their text alternatives should be consistent as well.
If there are two components on a web page that both have the same functionality as a component on another page in a set of web pages, then all 3 must be consistent. Hence the two on the same page will be consistent.
While it is desirable and best practice always to be consistent within a single web page, 3.2.4 only addresses consistency within a set of web pages where something is repeated on more than one page in the set.
Example 1: Document Icon
A document icon is used to indicate document download throughout a site. The text alternative for the icon always begins with the word “Download," followed by a shortened form of the document title. Using different text alternatives to identify document names for different documents is a consistent use of text alternatives.
Example 2: Check Mark
A check mark icon functions as "approved", on one page but as "included" on another. Since they serve different functions, they have different text alternatives.
Example 3: Consistent references to other pages
A Web site publishes articles on-line. Each article spans multiple Web pages and each page contains a link to the first page, the next page and the previous page of the article. If the references to the next page read "page 2", "page 3", "page 4" etcetera, the labels are not the same but they are consistent. Therefore, these references are not failures of this Success Criterion.
Example 4: Icons with similar functions
An e-commerce application uses a printer icon that allows the user to print receipts and invoices. In one part of the application, the printer icon is labeled "Print receipt" and is used to print receipts, while in another part it is labeled "Print invoice" and is used to print invoices. The labeling is consistent ("Print x"), but the labels are different to reflect the different functions of the icons. Therefore, this example does not fail the Success Criterion.
Example 5: Save icon
A common "save" icon is used through out the site where page save function is provided on multiple Web pages.
Example 6: Icon and adjacent link to same destination
An icon with alt text and a link are next to each other and go to the same location. The best practice would be to group them into one link as per . However if they are visually positioned one above the other but separated in the source, this may not be possible. To meet the Success Criterion, the link text for these two links need only be consistent, not identical. But best practice is to have identical text so that when users encounter the second one, it is clear that it goes to the same place as the first.
Example 7: Example of a Failure
A submit "search" button on one Web page and a "find" button on another Web page both have a field to enter a term and list topics in the Web site related to the term submitted. In this case, the buttons have the same functionality but are not labeled consistently.
Text alternatives that are "consistent" are not always "identical." For instance, you may have an graphical arrow at the bottom of a Web page that links to the next Web page. The text alternative may say "Go to page 4." Naturally, it would not be appropriate to repeat this exact text alternative on the next Web page. It would be more appropriate to say "Go to page 5". Although these text alternatives would not be identical, they would be consistent, and therefore would satisfy this Success Criterion.
A single non-text-content-item may be used to serve different functions. In such cases, different text alternatives are necessary and should be used. Examples can be commonly found with the use of icons such as check marks, cross marks, and traffic signs. Their functions can be different depending on the context of the Web page. A check mark icon may function as "approved", "completed", or "included", to name a few, depending on the situation. Using "check mark" as text alternative across all Web pages does not help users understand the function of the icon. Different text alternatives can be used when the same non-text content serves multiple functions.