To record an interactive terminal test, perform the
  following steps:

  1. Pull down the Testing menu.

  2. Choose the Record menu item and the DECwindows...
     submenu item.

  3. Fill in the fields and press the OK button.

  You begin the recording session by pressing Compose/S.
  DTM then starts the specified application and records
  every action during the session until you end the
  session by pressing Compose/P. You mark screen images
  for comparison by pressing Compose/M.

  DTM records and places the input into a template file
  (test_name.SESSION) and the output into a benchmark
  file (test_name.BMK).