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

Dynamic Data Exchange
DDE
Dynamic Data Linking

    (DDE, originally Dynamic Data Linking, DDL) A
   Microsoft Windows 3 hotlink protocol that allows
   application programs to communicate using a client-server
   model.  Whenever the server (or "publisher") modifies part of
   a document which is being shared via DDE, one or more clients
   ("subscribers") are informed and include the modification in
   the copy of the data on which they are working.

   (1997-06-05)