WCAG Conformance Criteria 4

From WCAG WG

This proposed amendment to the definition of "Conforming Alternative Version" referenced in Conformance Criteria 4, ensures that the new Success Criteria that address small screens cannot be bypassed by providing a link to the conforming "large screen" version, which has different amount of content. It proposes to add Note 8:

  • Note 2: The alternate version does not need to be matched page for page with the original (e.g., the conforming alternate version may consist of multiple pages). <add>However, it should not force the user to navigate to a view optimized for another platform.</add>
  • Note 8: Views or layouts other than those delivered based on screen size, device type, user agent, etc can be considered "alternatives" ONLY IF they satisfy the fundamental requirement laid out in items 1, 2, 3, 4 of this definition
  • Note 9: Authors SHOULD only rely on having a "conforming alternate version" when compliance cannot be accomplished in any other way.


Here it is in Context:

conforming alternate version

version that

  1. conforms at the designated level, and
  2. provides all of the same information and functionality in the same human language, and
  3. is as up to date as the non-conforming content, and
  4. for which at least one of the following is true:
    1. the conforming version can be reached from the non-conforming page via an accessibility-supported mechanism, or
    2. the non-conforming version can only be reached from the conforming version, or
    3. the non-conforming version can only be reached from a conforming page that also provides a mechanism to reach the conforming version
  • Note 1: In this definition, "can only be reached" means that there is some mechanism, such as a conditional redirect, that prevents a user from "reaching" (loading) the non-conforming page unless the user had just come from the conforming version.
  • Note 2: The alternate version does not need to be matched page for page with the original (e.g., the conforming alternate version may consist of multiple pages).
  • Note 3: If multiple language versions are available, then conforming alternate versions are required for each language offered.
  • Note 4: Alternate versions may be provided to accommodate different technology environments or user groups. Each version should be as conformant as possible. One version would need to be fully conformant in order to meet conformance requirement 1.
  • Note 5: The conforming alternative version does not need to reside within the scope of conformance, or even on the same Web site, as long as it is as freely available as the non-conforming version.
  • Note 6: Alternate versions should not be confused with supplementary content, which support the original page and enhance comprehension.
  • Note 7: Setting user preferences within the content to produce a conforming version is an acceptable mechanism for reaching another version as long as the method used to set the preferences is accessibility supported.
  • Note 8: Views or layouts other than those delivered to the user agent, when delivery is based on screen size, device type, user agent, etc. can be considered "alternatives" ONLY IF they satisfy the fundamental requirement laid out in items 1, 2, 3, 4 of this definition. A view with a changed menu mechanism, more or less content, or a simplified interface, would have different functionality from the view that was delivered to the user agent and therefore would not qualify under item 2 of this definition.
  • Note 9: Authors SHOULD only rely on having a "conforming alternate version" when compliance cannot be accomplished in any other way

Comments from Patrick H. Lauke

Essentially, stripping out the "small screen" part, this says (to paraphrase): "if two views do not have the same functionality/content, they can't count as being 'alternatives'", which is the same as point 2 "provides all of the same information and functionality..."

The issue also goes deeper than simply "small screen" vs "large screen".

Perhaps better would be to add a note that clarifies that different views/layouts triggered based on screen size, device type, user agent, etc also count as being "alternatives" ONLY IF they satisfy the fundamental requirement laid out in 1, 2, 3, 4 (conform at designated level, provide same information/functionality, are up-to-date, have a way to switch)

David responds

I've incorporated the wider language as proposed, and left part of the previous proposal as an example of what it means.