The main documentation files for the mom macros are in HTML format. Additional, useful documentation is in PDF format. See the groff(1) man page, section “Installation Directories”, for their location.
The mom macros are in active development between groff releases. The most recent version, along with up-to-date documentation, is available at http://www.schaffter.ca/mom/mom-05.html.
The groff_mom(7) man page (type
man groff_mom at the
command line) contains a partial list of available macros, however their
usage is best understood by consulting the HTML documentation.