original submission:

> Subject: *.am files: repetition of contents of MFLAG and FFLAG for
> GROFFBIN
>
>   The file GROFFBIN (=test-groff)

No.

Makefile.am:GROFFBIN = $(abs_top_builddir)/groff

> already contains all tmac and font files used in the repository.

No, `GROFFBIN` does not.  `test-groff` is a shell script that configures environment variables such that tmac and font directories in both the source and build trees will be found, then calls the `groff` executable produced by the build.

>   This concerns "doc/doc.am" (DOC_GROFF) and "contrib/hdtbl/hdtbl.am"
> (HDTBLGROFF).

Automake files should define their own macros for calling the build tree's groff executable with appropriate flags, and in fact they already do this with DOC_GROFF and HDTBLGROFF (which should probably be renamed with an underscore for consistency).

One reason that this is a good idea is that it enables such Automake files to declare only the dependencies they require.  `test-groff` is for post-build evaluation (see INSTALL.extra) and "expects" everything to be built.  That makes it a poor choice for a within-build tool.
 

>   Arguments to a command overwrite internal assignments.

I don't know what you're trying to say here, but arguments to a groff command neither "overwrite" nor "override" "internal assignments", by which I assume you mean compiled-in defaults.  "-F" and "-M" options to groff (troff, nroff) supplement those defaults.

Please see the troff(1) man page.

I'm repurposing this ticket for some macro renames (it's somewhat seductive to rename "GROFFBIN" simply "GROFF", which doesn't appear to already be in use...but it might be too vague).

Otherwise I consider it invalid.