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

Open Software Foundation
OSF

    (OSF) A foundation created by nine computer vendors,
   (Apollo, DEC, Hewlett-Packard, IBM, Bull, Nixdorf,
   Philips, Siemens and Hitachi) to promote "Open
   Computing".  It is planned that common operating systems and
   interfaces, based on developments of Unix and the X Window
   System will be forthcoming for a wide range of different
   hardware architectures.  OSF announced the release of the
   industry's first open operating system - OSF/1 on 23 October
   1990.

   (1994-11-23)