Accessible Name Guidance by Role Section: Change marquee name from required to discretionary

[smhigley]

Related to w3c/aria#1339 and w3c/aria#1342 on the ARIA repo.

I chose "discretionary" to match the guidance for log.

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Preview | Diff

[jnurthen]

I think this is ok but we could consider changing this to match the other discretionary roles which describe why you might want to give it an accessible name. However - I'm not sure I can really come up with a valid use case for that.

[carmacleod]

It's valid to give a marquee a name, just didn't make sense to require it.

I very quickly tested 4 marquees using jaws/nvda in chrome/ff.

Notes:

• The first 2 marquees use (obsolete) HTML <marquee> elements. One has aria-labelledby and the other has aria-label.
• The next 2 are fake marquees that use a span (I didn't add any animation). As above, one has aria-labelledby and the other has aria-label.
• Both browsers expose the role correctly, but I had to use role="marquee" ("belts and braces" style) on the 2 HTML <marquee> elements (otherwise, they just had a generic text container role).
• Both browsers expose all 4 accessible names correctly, and they also expose the aria-live="off".
• Both screen readers read the aria-labelledby span, because it's visible text content. :)
• Neither screen reader read the aria-label.
• Both screen readers read all of the marquee's content, i.e. they ignored the animated scrolling.

So we could say something along the lines of, "When naming a marquee, aria-labelledby with a visible label is recommended, because some screen readers do not read an aria-label on a marquee."

I'll try Safari/VO tomorrow.

Edit: Safari/VO reads all 4 marquees well (using VO+arrows), and even reads the name of the 2 aria-label marquees. The explicit role was also needed on the obsolete html marquee elements (same as Chrome/FF).

[carmacleod]

Thanks, @smhigley !
Ok to go in as-is, but consider adding more specific info in the guidance column.

[mcking65]

Thank you @smhigley!