Support for abbreviations and definitions in Pandoc's Markdown

[barriteau]

Maybe Pandoc's Markdown could be extended to support inline abbreviations and inline definitions, this to improve the already requested feature of built-in support for indices (#6415). The glossaries package (https://ctan.org/pkg/glossaries) could provide what's needed for a consistent Latex/PDF implementation of this.

An inline_abbreviations extension would provide support to the following markup (suggested syntax are just vague ideas):

**[ ... ] for simple abbreviations, equivalent to <abbr> ... </abbr> in HTML.

**[ ... ][ ... ] for expanded abbreviations, equivalent to <abbr title=" ... "> ... </abbr> in HTML.

An inline_definitions extension would provide support to the following markup:

:[ ... ] for simple definitions, equivalent to <dfn> ... </dfn> in HTML. If possible, nested abbreviations would be allowed, something like: :[ ... **[ ... ][ ... ]]

Examples:

Inline abbreviation

Entries like:
Hypertext Markup Language (**[HTML]) is a markup language used to...

Will become:
Hypertext Markup Language (<abbr>HTML</abbr>) is a markup language used to...

Inline abbreviation with expansion

Entries like:
Hypertext Markup Language (**[HTML][Hypertext Markup Language]) is a markup language used to...

Will become:
Hypertext Markup Language (<abbr title="Hypertext Markup Language">HTML</abbr>) is a markup language used to...

Inline definition

Entries like:
:[Hypertext Markup Language] (HTML) is a markup language used to...

Will become:
<dfn>Hypertext Markup Language</dfn> (HTML) is a markup language used to...

Inline definition and inline abbreviation in tandem

Entries like:
:[Hypertext Markup Language (**[HTML])] is a markup language used to...

Will become:
<dfn>Hypertext Markup Language (<abbr>HTML</abbr>)</dfn> is a markup language used to...

Inline definition and inline abbreviation with expansion, in tandem

Entries like:
:[Hypertext Markup Language (**[HTML][Hypertext Markup Language])] is a markup language used to...

Will become:
<dfn>Hypertext Markup Language (<abbr title="Hypertext Markup Language">HTML</abbr>)</dfn> is a markup language used to...

Reference

HTML definitions tag:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dfn

HTML abbreviation tag:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/abbr

HTML definitions list tags (already supported in Pandoc's Markdown):
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dl
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/dt

[anasram]

Starting from this valid syntax in pandoc's markdown:

in markdown:

Also, [HTML](https://html.spec.whatwg.org/ "Hypertext Markup Language") is a markup language used to...

in HTML:

Also, <a href="https://html.spec.whatwg.org/" title="Hypertext Markup Language">HTML</a> is a markup language used to...

the result:

Also, HTML is a markup language used to...

An abbreviation with a title could be supported like this:

Also, [HTML]("Hypertext Markup Language") is a markup language used to...

Also, <abbr title="Hypertext Markup Language">HTML</abbr> is a markup language used to...

Simply, just a titled markdown link without a link!

I don't think it's worth it to mark an abbreviation tern as an abbreviation without a title.

[barriteau]

@anasram, that for sure would be a lot simpler and intuitive syntax :)

Same as you, I used to think it was pointless not using a title attribute in the abbr tag, but the standard has a clever and fair point about that:

Only include a title if expanding the abbreviation or acronym in the text is not possible. Having a difference between the announced word or phrase and what is displayed on the screen, especially if it's technical jargon the reader may not be familiar with, can be jarring.

(https://developer.mozilla.org/en-US/docs/Web/HTML/Element/abbr#accessibility_concerns)

It seems the tag is primarily intended to point "this is an abbreviation" and expanding to the meaning of it is optional.

Maybe just omitting the abbr tag is a solution when no title attribute is going to be used, but at least for the indices creation a not expanded abbr could be of use.

[anasram]

Will, in this case, it could be simply [HTML]() or [HTML]("").