Enables you to determine whether you are using the debugger's
    command interface or DECwindows Motif interface. With the
    DECwindows Motif interface, the value of %DECWINDOWS is 1 (TRUE).
    With the command interface, the value is 0 (FALSE). For example:

    DBG> EVALUATE %DECWINDOWS
    0

    The following example shows how to use %DECWINDOWS in a debugger
    initialization file to position the debugger source window, SRC,
    at debugger startup:

    IF %DECWINDOWS THEN
       ! DECwindows Motif (workstation) syntax:
       (DISPLAY SRC AT (100,300,100,700))
    ELSE
       ! Screen-mode (terminal) syntax:
       (DISPLAY SRC AT (AT H1))