4.2 Compiling and Linking to Prepare for Debugging
  The following example shows how to compile and link a
  BASIC program (consisting of a single compilation unit
  named INVENTORY) so that subsequently you will be able to
  use the debugger:
  $ BASIC/DEBUG INVENTORY
  $ LINK/DEBUG INVENTORY

  The /DEBUG qualifier with the BASIC command instructs
  the compiler to write the debug symbol records associated
  with INVENTORY into the object module, INVENTORY.OBJ.
  These records allow you to use the names of variables and
  other symbols declared in INVENTORY in debugger com-
  mands. (If your program has several compilation units, you
  must compile each unit that you want to debug with the
  /DEBUG qualifier.)

  The /DEBUG qualifier with the LINK command instructs the
  linker to include all symbol information that is contained in
  INVENTORY.OBJ in the executable image. The qualifier also
  causes the OpenVMS image activator to start the debugger at
  run time. (If your program has several object modules, you
  may need to specify other modules in the LINK command.)