The W3C WAI develops Web accessibility guidelines for the different components:

• Authoring Tool Accessibility Guidelines (ATAG)

• Web Content Accessibility Guidelines (WCAG)

• User Agent Accessibility Guidelines (UAAG)

WAI guidelines are based on the fundamental technical specifications of the Web, and are developed in coordination with:

• W3C technical specifications (HTML, XML, CSS, SVG, SMIL, etc.)

http://www.w3.org/WAI/intro/components.php