revise data-ams-doc=secX

[pkra]

secX is another leftover from htmlbook. In XML this is disp-level.

We also have a level attribute which serves the same purpose as sectX.

Both ams-doc-level="X" or ams-doc="level X" would be cleaner and easier to reuse downstream (where we extract the X for various purposes).

[pkra]

I'm leaning towards ams-doc-level (which is more reminiscent of aria-level which is a matching concept used to create headings without or beyondh1-h6 tags).

Using -level would allow us to keep data-ams-doc closer to "something like DPUB ARIA role" (which are prefixes doc-) - currently the only other values for data-ams-doc after #215 are titlepage, copyright-page, and article.

In addition, we could then change data-jats-structure (current values: section, subsection, subsubsection, paragraph and one empty attribute in jams410) to data-ams-doc which would be another good match to the "DPUB ARIA role-like" idea for data-ams-doc.

[pkra]

Correction: another value for data-jats-structure is part (books only).

[pkra]

Related: dedication (books) and ack elements (jams410 only) do not have a disp-level but we add sectX to them.