[WCAG AAA] - Move H28 from sufficient to advisory in 3.1.4 Abbreviations SC

[giacomo-petri]

Closes: #3019

H28 is not a sufficient technique, rather than an advisory one, since it would likely fail 2.1.1

Actions: moved H28 from sufficient to advisory.

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[bruce-usab]

Discussed on Backlog call 1/17. Moved to Ready for approval.

[mbgower]

IMO, there should be some language inside the technique, and maybe inside the Understanding document (i.e., in the final example), explaining the matter raised in the issue.

The SC language reads:

A mechanism for identifying the expanded form or meaning of abbreviations is available.

The use of <abbr> with an appropriate value for the title attribute clearly provides a mechanism for identifying the meaning of the abbreviation. So we have to be clear that the reason this is not sufficient is because of the note in the definition of mechanism

The mechanism needs to meet all success criteria for the conformance level claimed.

The argument is that use of title fails to meet 2.1.1 Keyboard and so is not a sufficient mechanism, correct? We should state that.

[bruce-usab]

I am of the opinion that something should be added to H28 explaining why it has been down graded from sufficient to advisory.

Keyboard support for abbr has been weak, but historically we didn't assert that the default behavior of the element fails 2.1.1. But maybe enough time has passed that we should?

[bruce-usab]

Discussed on backlog call 2/7. @mbgower agreed to take another pass, stays in For discussion.

[bruce-usab]

Discussed on backlog call 2/21. Keeping in For Discussion as Mike is still has this in his queue.

[mbgower]

I have added an explanation to the top of the H28 techniques which I think resolves this.