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UAAG: User Agent Accessibility Guidelines

Once captions have been created, they become useful to viewers only if they can actually be watched. Any software that permits the viewing of captions is a user agent. Just as Web content and authoring tools must be accessible, so too must these user agents, requirements for which are given in the User Agent Accessibility Guidelines.



Compliance with UAAG can be viewed as a reasonable indicator that a program is accessible. Two UAAG evaluations of media players have been published, one for RealPlayer, another for Windows Media Player.

Evaluation results were better than average for both players. RealPlayer’s implementation of User Agent Accessibility Guidelines was “complete,” “very good,” or “good” in 30 out of 42 checkpoints that were rated. (48 others were “not rated.”) Windows Media Player scored 14 “complete,” “good,” or “very good” implementations out of 27 that were rated. (16 others were “not applicable” and 47 others were “not rated.”)

Setting aside inapplicable guidelines, though, there are still significant questions about the accessibility of these two players. The checkpoints rated “poor” or “not implemented” were numerous. The number of checkpoints “not rated” dwarfs the number that were rated in both evaluations.


Because of the likely inaccessibility of user agents, some people with disabilities will find it inconvenient, difficult, or impossible to watch captions.

Revision history

Fixed error in Implications section (ATAG implications misapplied).