/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