V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

OCX
       OLE Control eXtensions (MS)


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

OLE custom controls
OCX

    (OCX) An Object Linking and Embedding
   (OLE) custom control allowing infinite extension of the
   Microsoft Access control set.  OCX is similar in purpose to
   VBX used in Visual Basic.  Available OCX's include "Scroll
   Bar Control", "Calendar Control", and "Data Outline Control".

   [Details?]

   (1995-12-05)