The Free On-line Dictionary of Computing (30 December 2018):

GCAL

    The Cambridge Phoenix equivalent of troff.
   So called because all Cambridge utilities were named after
   birds, GCAL was a "run off" equivalent, and Geococcyx
   californianus is the Latin name of the roadrunner.  GCAL was
   eventually obsoleted by TeX.

   It is believed that even more obscure puns lurked in the
   depths of Phoenix.  Perhaps it is better they stayed there.

   (2003-12-05)