A web technology is accessibility supported whenever (1) it supports the users' assistive technologies or (2) it provides its own supported assistive technology through user agents that are equally available to users with and without disabilities.
This yields the following rule of WCAG 2.0 compliance for content that invokes Web technologies.
Web content that is otherwise WCAG 2.0 compliant remains WCAG 2.0 compliant whenever every element of Web technology it invokes is accessibility supported
A web technology is accessibility supported whenever: (1) it supports the users' assistive technologies or (2) it provides its own supported assistive technology through user agents that are equally available to users with and without disabilities.
This begs the question: What is accessibility support for a user's assistive technology.
An assistive technology is supported by a Web Technology if either:
Combined these definitions say that a Web technology is accessibility supported if it supports user's assistive technology or it provides assistive technology of its own that supports all users of the Web technology equally.
Now not every part of a Web technology need be accessibility supported for the content that invokes it to satisfy WCAG 2.0 compliance. If the elements of all the Web technologies invoked by a piece of otherwise compliant web content are accessibility supported then the content is WCAG 2.0 compliant. As long as the unsupported elements of Web technology do not interfere (are not invoked) by the Web content then the Web content remains compliant.