WAI-ARIA Taxonomy

The WAI-ARIA taxonomy can be represented visually as a UML class diagram. Versions of this diagram available are:

• SVG diagram that is scalable, displays well on screen and for print;
• PNG diagram for on-screen viewing (a small PNG preview version is also available).

In addition to visual representations of the diagram, the semantics of the diagram are expressed in the following formats:

• UML XML that can be imported into editors supporting the format;
• RDF that can be processed by RDF-aware tools.

The above formats have varying levels of accessibility. The visual representation is very helpful to some users, and others may benefit from the semantic versions. If you do not prefer the above formats, the WAI-ARIA Roles Model itself contains the same information as the diagram. The relationships in the diagram can be understood by navigating the cross reference links in the specification. This document provides instructions to obtain the information from the specification that is available in the diagram.

The class diagram provides information about roles and their inheritance. Arcs from a given role point to roles from which it inherits; following the arc in reverse indicates descendant roles. States and properties that are supported or required for the role are shown as attributes in the class diagram; these inherit into descendant roles.

To view these relationships in the WAI-ARIA specification, use the following procedures when looking at a given role. The base role is "roletype", or you may select a role from the index of roles in Definition of Roles. The information about each role is in a table named "Characteristics of <role name>".

• If the role is abstract, there is a row with header "Is Abstract" and value "True". If this row is not present, it is a concrete role.
• Roles from which the current role inherits are shown in a row with the header "Superclass Role". Follow the links to examine those roles.
• Roles that descend from the current role are shown in a row with the header "Subclass Role". Follow the links to examine those roles.
• Required states and properties are listed in a row with the header "Required States and Properties". Supported (but not required) states and properties are listed in a row with the header "Supported States and Properties".
• States and properties that inhert from roles higher in the taxonomy are listed in a row with the header "Inherited States and Properties". They can also be inferred by following links to superclass roles, up the chain.

If a row described above is not in the characteristics table for a given role, that characteristic does not exist on the role.

The links between the roles are reflexive, so it is possible to traverse up and down the hierarchy to explore it.