How to Implement WCAG 1.0: Strategies for Testing Web sites and Web Applications

Web Content Accessibility Guidelines
The characteristics that accessible content need to possess
User Agent Accessibility Guidelines
How to make user agents accessible
Authoring Tool Accessibility Guidelines
What is an accessible authoring tool and how should it produce accessible content?
XML Accessibility Guidelines
Creating XML languages that can be used to create accessible content

WCAG is One in a Four Part Suite