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

Here you'll find additions to the Automake base distribution, in form of
makefile fragments, m4 macros, scripts, documentation, et cetera.  Such
addition that might be useful for a significant percentage of its general
audience, but (for one reason or another) are not deemed appropriate for
inclusion into the Automake core.

There are several reasons for which a feature can be kept in contrib:

  1. The long-term usefulness of the feature is debatable and uncertain;
     on-field and real-word testing are 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 the
     support for backward-compatibility, even if the features proves
     flawed or fails to attract widespread use).

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

  3. The feature was an historical one, mostly obsoleted but still used
     "here and there" in the wild; so we want to to deprecate it and
     remove it from the Automake core, but cannot remove it altogether,
     for the sake of those still-existing usage.  So it gets moved in
     contrib.