1.4.10 Linearization

WCAG 2.1 Review: Introduction 

WCAG 2.1 now has a first public working draft and ​the working group are inviting comments and feedback via Github

As I'm developing software to test sites for accessibility, I'm reviewing the 28 new proposed criteria for WCAG 2.1, primarily to determine how testable the criteria are using either automated or manual methods. ​

This post concerns a specific criterion: ​1.4.10 Linearization. 
To view my feedback on other criteria and more background info, go to my listing of feedback

The Criterion

  • 1.4.10 Linearization
  • Suggested Priority Level: A
  • Text: A mechanism is available to view content as a single column, except for parts of the content where the spatial layout is essential to the function and understanding of the content.

My Thoughts

The purpose of this criterion is simple to understand for developers and testers, although there is a little wiggle room for interpretation of when layout is essential. I'd support it being renamed to "SIngle Column" though, as the titles should always be really simple to interpret. 

This success criterion is not clear enough on who provides the mechanism for reflowing content to a single column, and what that mechanism should be, though from the comments it appears that the reflow will be provided by user agents/scripts and not implemented by the developers.

The main issue is that the recommended method for testing is to switch off CSS, but this will cause content that has been hidden using display:none or similar to become visible. With responsive sites, the reliance on CSS to show / hide content has increased and so switching it off could cause very confusing displays indeed.

I feel that to make this a solid success criterion, there needs to be some form of browser plugin or script that is endorsed by the W3C for testing the reflow in HTML. Otherwise, there is too much subjectivity in the testing technique, and just switching off CSS completely will be too problematic. ​

Overall, this needs the method for testing HTML content firming up before release, but it is clear otherwise.

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