This is the 'contrib' directory of the GNU Automake distribution.

Here you'll find additions to the Automake base distribution, in the form of
makefile fragments, m4 macros, scripts, documentation, et cetera: additions
that might be handy to many users, but (for one reason or another) are not
deemed appropriate for inclusion into the Automake core.

There are several reasons that a feature might be kept in contrib:

  1. The long-term usefulness of the feature is debatable and uncertain;
     real-world testing is necessary to prove or disprove its usefulness,
     before the feature can be committed into the Automake core (as doing so
     too early would later force us to continue support for
     backward-compatibility, even if the feature proved flawed or fails to
     attract widespread use).

  2. The APIs or overall design of the feature are still unstable, and need
     testing to iron out warts and usability bugs, or uncover potential flaws.

  3. The feature was an historical one, mostly obsolete but still used in the
     wild.  We want to deprecate it and remove it from the Automake core, but
     cannot remove it altogether, for the sake of the existing usage, so it
     gets moved to contrib.