should alttitle "output" contain label content?

[pkra]

While working on #452, I noticed this

texml-to-html/lib/elements/label.js

Line 63 in 70fa67c

container.setAttribute('data-ams-doc-alttitle', container.textContent + altTitle.innerHTML); // NOTE assumes previousSibling handled first

which somewhat vaguely describes that we push not only the alt-title but also the (processed) label content into the data attribute.

Besides a risk of containing complex markup (e.g., from math mode), I'm wondering if this should be revisited.

E.g., the attribute could be renamed or split into 2 (for alt title & label). Then again, we can nowadays pick up the label downstream so we could also revert this back to just the title (in which case it should probably move to the title element output).