Add "none" as conformance option

[mattgarrish]

This pull request adds text on using "none" as a value of a dcterms:conformsTo property when a publication does not meet accessibility standards.

This fits into the existing note about claiming conformance to WCAG or other standards, as I don't think we should try to write a normative requirement for something we can't enforce. Adding to that note would make it very large, however. Instead, I've changed the note into an informative subsection called "Other accessibility claims".

(Hopefully, changing an informative note to an informative section also keeps us in the scope of a class 2 change rather than a class 3.)

I was also able to work in a link to the exemption property we're defining in the other pull request, but we'll have to publish that first to make the reference valid.

I didn't add a change log entry, as I don't know if calling it a "substantive change" would trigger people to question the classification. Or at this stage do we need to document all changes in the logs @iherman?

Fixes #2569

[mattgarrish]

Forgot the preview and diff links:

• preview
• diff

[avneeshsingh]

Looks good!

[iherman]

@mattgarrish let me talk to PlH next week (I will have a 1-1 with him) regarding your editorial questions, @mattgarrish. I expect that if we do a republish with classes 1-2, then we can directly publish as we wish, and I expect it is all right to add a change log as we did. We know that if we publish class 3 we must be careful, because we have to publish a document with the diffs clearly marked (and then reviewed by the AC). I do not know what happens if we publish a new version with classes 1, 2, and 3…

[iherman]

(Hopefully, changing an informative note to an informative section also keeps us in the scope of a class 2 change rather than a class 3.)

I would think it is class 2.

I have added a label on this, we will have to do that systematically...