O'Reilly's SGML formatting package.

This package processes the complete sources for a book in DocBook
format and formats it with groff.

This port is the first port of what was previously an internal
O'Reilly product.  Consider it beta quality.  The copyright
information in the README file states:

  # This is ALPHA software.  Permission to redistribute this alpha
  # version is expressly denied.

According to Lenny Muellner <len@oreilly.com>, this is out of date,
but the archive has not yet been updated.

The only documentation is gmat.sgm.  To format, 

  # gmat gmat.sgm

The results of the formatting are not exactly production quality.
There is still a lot of work to be done.