VMS Help DTM, SHOW, TEST_DESCRIPTION, Parameter Qualifiers, /GROUP  *Conan The Librarian (sorry for the slow response - running on an old VAX)

   Identifies the immediately preceding item in the parameter as a
   group expression. If a test group expression comprises a list, use
   this qualifier after each item that designates a group.

   Because of the existence of the /GROUPS qualifier for this
   command, you cannot abbreviate the /GROUP qualifier.