This appears to be an updated version of bug #45034.

I reckon this would be something new for the contrib directory; updating Category, Item Group, and Severity accordingly.

Hello.

Another try to establish the mdocmx(7) reference+ extension at groff(1)'s mdoc(7), after the failed attempt in 2015, which, granted, was based on a pretty crude grotty(1) extension.

But in 1.23 with the OSC 8 extension to grotty(1) groff delivers out of the box, and less(1) also at least ignores OSC 8 for a while.  With the now fully-featured less(1) enhancement request

  https://github.com/gwsw/less/pull/251

the combination of groff(1)/mdoc(7)/mdocmx(7)/grotty(1) plus less(1) delivers a fully referenced manual experience, with optional table of contents and more.

The attached file contains a git(1) mail-patch MBOX to be used with git(1) am.

The first changeset hooks mdocmx(7) into mdoc(7).  The largest change needs to happen in doc-print-recursive, which will henceforth know who its caller was.
These changes do not change functionality of plain mdoc(7).
A mdoc(7) file must make explicit use of the extension in order to load the actual mdocmx contribution.

The second adds contrib/mdocmx.

In general mdocmx requires a new sh(1)/awk(1) based preprocessor in order to provide its functionality, as troff(1) is single-pass, and therefore forward references cannot be created.
However, the mdocmx preprocessor will put a cookie so that the actual mdocmx macros know what to do (to be upward compatible with a two-pass troff(1) that may spring into existence in a future time).  Therefore preprocessed manuals can be distributed.
(I release them like that for the programs i maintain since i think 2015, and they become interactive in the second where there is a capable roff.)

mdocmx(7) has one problem left, described in the BUGS section of the contained mdocmx.7 manual.  Only a rewrite of mdoc(7) as such can fix this.  (A survey in 2015 has shown that some BSD manuals indeed do use referenceable and formatting macros in header lines, these would have to adapted to be compatible with mdocmx.  But since you must write for mdocmx anyway, this is a hypothetical issue.)

Conclusion: with the MBOX applied to 1.23, and with a less(1) including the pull request, one should be able to go up up and away like

  groff -Tutf8 -mdoc mdocmx.7 | less -R

Note the manuals mdocmx.7 and mdocmx.1 are installed in a preprocessed way for groff, so "man 7 mdocmx" should also rock.
And "MDOCMX_FLAGS=64 man 7 mdocmx" should also produce a table of contents.

Ciao!

P.S.: hihihi, now that i explicitly added an account, Savannah allows notification Cc: specification!