There are five requirements that must be met in order for content to be classified as 'conforming' to WCAG 2.0.
One of the following levels of conformance is met in full:
Note 1: For the purpose of determining conformance, alternatives to part of a page's content are considered part of the page when the alternatives can be obtained directly from the page, e.g., a long description or an alternative presentation of a video.
Note 2: Authors of Web pages that cannot conform due to content outside of the author's control may consider a Statement of Partial Conformance.
The first requirement deals with the levels of conformance. It basically says that all information on a page conforms or has a conforming alternate version that is available from the page. The requirement also explains that no conformance is possible without at least satisfying all of the Level A Success Criteria.
Conformance (and conformance level) is for full Web page(s) only, and cannot be achieved if part of a Web page is excluded.
Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.
Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.
This provision simply requires that the whole page conform. Statements about "part of a page conforming" cannot be made.
Sometimes, supplemental information may be available from another page for information on a page. The longdesc attribute in HTML is an example. With longdesc, a long description of a graphic might be on a separate page that the user can jump to from the page with the graphic. This makes it clear that such content is considered part of the Web page, so that requirement #2 is satisfied for the combined set of Web pages considered as a single Web page. Alternatives can also be provided on the same page. For example creating an equivalent to a user interface control.
Note: Because of conformance requirement 5, a whole page may conform even if parts of the page use non accessibility-supported content technologies as long as they do not interfere with the rest of the page and all information and function is available elsewhere on or from the page.
When a Web page is one of a series of Web pages presenting a process (i.e., a sequence of steps that need to be completed in order to accomplish an activity), all Web pages in the process conform at the specified level or better. (Conformance is not possible at a particular level if any page in the process does not conform at that level or better.)
Example: An online store has a series of pages that are used to select and purchase products. All pages in the series from start to finish (checkout) conform in order for any page that is part of the process to conform.
This provision prevents a Web page that is part of a larger process from being considered conforming if the process overall is not. This would prevent a shopping site from being classified as conforming if the checkout or other features of the site that are part of the shopping and buying process do not conform.
Only accessibility-supported ways of using technologies are relied upon to satisfy the success criteria. Any information or functionality that is provided in a way that is not accessibility supported is also available in a way that is accessibility supported.
Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.
Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.
This conformance requirement is explained below under Understanding Accessibility Support.
If technologies are used in a way that is not accessibility supported, or if they are used in a non-conforming way, then they do not block the ability of users to access the rest of the page. In addition, the Web page as a whole continues to meet the conformance requirements under each of the following conditions:
In addition, the following success criteria apply to all content on the page, including content that is not otherwise relied upon to meet conformance, because failure to meet them could interfere with any use of the page:
This basically says that technologies that are not accessibility supported can be used, as long as all the information is also available using technologies that are accessibility supported and as long as the non-accessibility-supported material does not interfere.
Technologies that are not accessibility supported can be used, or technologies that are accessibility supported can be used in a non conforming manner, as long as all the information is also available using technologies that are accessibility supported, in a manner that does conform, and as long as the non-accessibility-supported material does not interfere.
There are four provisions that particularly deal with issues of interference with use of the page. These four are listed bove. Each of the provisions indicates the Success Criteria that need to be met for all content including content created using technologies that are not accessibility supported.
Example: A Web page incorporates a new interactive graphic technology called "ZAP". Although ZAP is accessibility-supported, the information that is presented in ZAP is also presented on the page in HTML, so ZAP is not relied upon. So, this page would pass conformance requirement #1. However, if the user tries to tab through the ZAP content, the focus drops into the ZAP object and gets stuck there. Once inside, there is nothing the user can do to get the focus back out. So keyboard users cannot use the bottom half of the page. The ZAP content also is continually flashing brightly at different rates and doesn't stop. So, people with attention deficit are distracted and those with photosensitive seizure disorders may have seizures. Conformance requirement #5 prevents situations like these from being possible on a conforming page.