Remove/Deprecate mglyph element

[fred-wang]

Currently this is not defined in MathML Core, only MathML 4.

• I think the need for custom glyph is already covered with modern HTML5 technologies by using web fonts and "Private Use Areas".
• If people want to use image, they can embed an HTML img tag into an mtext.

In any case, I think the idea of mglyph is a rather hacky temporary workaround. Ideally, people use characters defined in Unicode. These days, they should have enough characters available to write math.

[physikerwelt]

discussed in the telco on 2019-02-25:

• patrick ion points out that generating new glyphs is something which is used heavily in mathematics, .e.g, in knot theory.
• embedding HTML would be a more powerful option and superseded the mglyph functionality

[pdfion]

There was apparently a technology proposed for CJK gaiji that would do just fine for supplemental math characters: SING and replace . I have no idea if this is viewed as a current technology. Anyone know?
References:

• https://en.wikipedia.org/wiki/OpenType#SING_gaiji_solution
  ** The SING (Smart INdependent Glyphlets)[81][82] technology that made its debut with Adobe's Creative Suite 2 allows for the creation of glyphs, each packaged as a standalone font, after a fashion. Such a packaged glyph is called a glyphlet. The format, which Adobe has made public, is based on OpenType.
• SING: Adobe’s New Gaiji Architecture,Jim DeLaHunt (2004) | http://partners.adobe.com/public/developer/en/opentype/SING_Intro_IUC26.pdf

[pdfion]

That should read SING could replace mglyph.

[fred-wang]

@pdfion Thanks for the information. I think someone should investigate more, maybe contact people from CSS / Font WG to see if that's the kind of features already available in browsers ( https://drafts.csswg.org/css-fonts-3/ ). In any case, that aligns with the idea that this is something that has to be provided by CSS/font so we should just rely on it instead of defining our own feature in MathML.

(PS: I've fixed the formatting in your comment)

[dani31415]

While it is somehow acceptable that MathML4 is MathML3 + CSS - deprecation of attributes, if we remove the mglyph, we loss the capability of inserting images in MathML (for the case that the MathML is not part of an HTML 5).

I suggested Stand-alone MathML profile #58. Just in case we forgot that MathML should also exist outside web pages.

Maybe you are referring to MathML core. In which case the issue should be relaveled to core.

[NSoiffer]

@dani31415: is WIRIS using mglyph? If so, can you elaborate on the use case?

[davidcarlisle]

@dani31415 I agree that we should ensure that mathml is usable in non css environments and that this means we should keep elements such as mglyph in full (not core) unless there is an alternative available.

[fred-wang]

I'm interested in removing it from core (it is already not present, but just to confirm). Then I'll let others decide what to do in other specs, whether to write a polyfill etc