This Wiki page is edited by participants of the WCAG Working Group. It does not necessarily represent consensus and it may have incorrect information or information that is not supported by other Working Group participants, WAI, or W3C. It may also have some very useful information.
WCAG definition of role
text or number by which software can identify the function of a component within Web content
Example: A number that indicates whether an image functions as a hyperlink, command button, or check box.
Additional guidance when applying to Electronic Documents and Software Aspects of Products
This applies directly as written, and as described in WCAG 2.0 glossary replacing "Web Content" with "Content".
NOTE: "AccessibleRole" (or however it is called in different APIs) of the Accessibility API of the platform is an example of such a role.