The Free On-line Dictionary of Computing (19 January 2023):

Mops

   Like Yerk, Mops is descended from the ex-commercial
   object-oriented language Neon.  It was developed by
   Michael Hore .  Mops features an
   optimising native-code compiler; it is much faster than
   Yerk, but less compatible with Neon.  Mops includes extensions
   such as multiple inheritance.

   Version 2.3.1 includes a compiler, documentation and an
   editor.

   A Macintosh version is available.
   (ftp://oddjob.uchicago.edu/pub/Yerk).