Human Computer Interaction
ERCIM News No.46, July 2001 [contents]

The W3C Web Accessability Iinitiative User Agent Accessibility Guidelines 1.0

by Ian Jacobs and Daniel Dardailler

The User Agent Accessibility Guidelines (UAAG) 1.0 is the third of a trilogy of accessibility guidelines published by the Web Accessibility Initiative (WAI) of the World Wide Web Consortium. These documents were designed to present a consistent model for Web accessibility in which responsibilities for addressing the needs of users with disabilities are shared (and distributed among) authors, software developers, and specification writers.

Ms. Laitinen is an accountant at an insurance company that uses Web-based formats over a corporate intranet. She is blind. She uses a screen reader in conjunction with a graphical desktop browser and a speech synthesizer. She uses speech output, combined with navigation of the important links on a page, to scan documents rapidly for important information, and has become accustomed to listening to speech output at a speed that her co-workers cannot understand at all.

For Ms. Laitinen it is critical that her desktop browser communicate with available assistive technologies (screen reader, speech synthesizer), so UAAG 1.0 includes requirements related to communication (through programming interfaces) and to the implementation of system conventions (which increase the likelihood of interoperability). Communication with her assistive technology does not suffice to make her browser more accessible, however. Some of her other needs include:

‘User Agent Accessibility Guidelines 1.0’explains what software developers can do to improve the accessibility of mainstream browsers and multimedia players so that people with hearing, cognitive, physical, and visual disabilities will have improved access to the World Wide Web. UAAG 1.0 is developed by the W3C User Agent Accessibility Guidelines Working Group, whose participants include software developers, users with disabilities, and international experts in the field of accessibility technologies.

UAAG 1.0 is the third of a trilogy of accessibility guidelines published by the Web Accessibility Initiative (WAI) of the World Wide Web Consortium. The other two documents are:

Details on the Guidelines
UAAG 1.0 explains the responsibilities of user agents in meeting the needs of users with disabilities. A user agent that conforms to these guidelines will enable access through its own user interface and through other internal facilities, including its ability to communicate with other technologies (especially assistive technologies such as Ms. Laitinen’s screen reader).

Checkpoints and Guidelines
The heart of UAAG 1.0 consists of nearly ninety ‘checkpoints’, each of which includes one or more requirements. The checkpoints are ranked according to their importance to accessibility (priority 1 for most important, then priority 2 and 3). Here is one example of a checkpoint:

• Checkpoint 1.1 Ensure that the user can operate the user agent fully through keyboard input alone. [Priority 1]

Checkpoints are organized into twelve ‘guidelines’. Each guideline expresses a general principle of accessible design. Here is one example of a guideline:

• Guideline 4: Ensure user control of rendering. Ultimately, the user must have final control over the rendering and behaviour of both the content and the user interface. While it is important to preserve the author’s intentions as much as possible, without final user control, some content may not be usable at all by some users with disabilities.

A user agent may satisfy the requirements of UAAG 1.0 in many different ways. The checkpoints of UAAG 1.0 have therefore been written to be independent of specific markup languages (eg, the Hypertext Markup Language (HTML) or Scalable Vector Graphics (SVG)) and operating systems. To assist developers in understanding how to satisfy the requirements for specific technologies and operating systems, the User Agent Accessibility Guidelines Working Group has published a separate document entitled ‘Techniques for User Agent Accessibility Guidelines 1.0’ ( This document includes references to other accessibility resources (such as platform-specific software accessibility guidelines), examples, and suggestions for approaches that may be part of satisfying the requirements of UAAG 1.0.

The ‘User Agent Accessibility Guidelines 1.0’ are currently at the ‘last call’ stage of the W3C Recommendation track. This means that the UAWG has requested technical review from the Web community, and intends to request advancement to Candidate Recommen-dation once review comments have been processed. The UAWG anticipates that UAAG 1.0 will become a W3C Recommendation in late 2001. At that time, we look forward to it being an important resource for promoting Web accessibility.

World Wide Web Consortium:
Web Accessibility Initiative:
W3C User Agent Accessibility Guidelines Working Group:
Web Content Accessibility Guidelines 1.0:
Authoring Tool Accessibility Guidelines 1.0’:
User Agent Accessibility Guidelines 1.0:

Please contact:
Ian Jacobs — W3C

Daniel Dardailler — W3C
Tel:+33 4 9238 7983