Qualifier

/DEBUG
      /DEBUG
      /NODEBUG

   Executes the image under control of the debugger. The default
   is the /DEBUG qualifier if the image is linked with the /DEBUG
   qualifier and the /NODEBUG qualifier if the image is linked
   without the /DEBUG qualifier. The /DEBUG qualifier is invalid if
   the image is linked with the /NOTRACEBACK qualifier. The /NODEBUG
   qualifier overrides the effect of the LINK/DEBUG command. If
   the image was linked with the /TRACEBACK qualifier, traceback
   reporting is performed when an error occurs.

   If the image was not linked with the debugger, you can specify
   the /DEBUG qualifier to request the debugger at execution time;
   however, if the /NOTRACEBACK qualifier was specified when the
   image was linked, the /DEBUG qualifier is invalid.

   For a complete description of the OpenVMS Debugger, see the VSI
   OpenVMS Debugger Manual.

   To get help on debugger commands from the DCL level, type the
   following command:

   $ HELP/LIBRARY=SYS$HELP:DBG$HELP DEBUG