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

Universal Communications X
UCX

    (UCX) A software implementation of the
   ubiquitous TCP/IP suite of communications protocols for
   Digital Equipment Corporation's OpenVMS operating
   system.

   Users of the UCX product can connect to heterogeneous
   networks to access and download files, send electronic
   mail, run and develop applications, and monitor activity.

   "Software Product Description, DIGITAL TCP/IP Services for
   OpenVMS, Version 4.2",
   (http://digital.com/info/QAW009/QAW009HM.HTM).

   (2000-12-15)