GSA Government-wide Section 508 Accessibility Program

WCAG 2.0 Conformance

The Revised 508 Standards require conformance to the W3C Web Content Accessibility Guidelines (WCAG) 2.0 Level AA. But what does that mean?

What Are the WCAG 2.0 Conformance Levels?

Conformance to a standard means that you meet or satisfy the 'requirements' of the standard. In WCAG 2.0 the 'requirements' are the Success Criteria, which are categorized in three levels:

  • Level A (minimum) – Addresses the most basic web accessibility features, but does not generally achieve broad accessibility.
  • Level AA (mid-range) – Addresses most common barriers for disabled users and aligns to the Revised 508 Standards
  • Level AAA (highest) – Addresses the highest level of web accessibility, but is not recommended as a general policy, because it is not possible to satisfy all criteria for some content.

What Does WCAG 2.0 Conformance Mean?

According to the W3C’s definition of conformance, there are five requirements that must be met in order for content to conform.

Requirement 1: Conformance Level

One of the following levels of conformance is met in full.

  • Level A: For Level A conformance (the minimum level of conformance), the web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided.
  • Level AA: For Level AA conformance, the web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.
  • Level AAA: For Level AAA conformance, the web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided."

Requirement 2: Full Pages

“Conformance (and conformance level) is for full web page(s) only and cannot be achieved if part of a web page is excluded."

Requirement 3: Complete Processes

“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."

Requirement 4: Only Accessibility-Supported Ways of Using Technology

“Only accessibility-supported ways of using technologies are relied upon to satisfy the success criteria." In other words, the way chosen to satisfy the Success Criteria will work with user agents and assistive technologies. Standard methods must be used to expose content to assistive technology or special accessibility features in mainstream user agents.

Requirement 5: Non-Interference

“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 other words, technologies that are not accessibility-supported can be used, as long as the non-accessibility-supported material does not interfere and all information is also available using technologies that are accessibility-supported.”

Note that conformance at a higher level also implies conformance at lower levels (i.e., conformance to Level AA implies conformance to Level A, as well).

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Page Reviewed/Updated: January 2018