Applies to a multiprocess debugging configuration (when
    DBG$PROCESS has the value MULTIPROCESS). Specifies the visible
    process. This is the process whose stack, register set, and
    images are the current context for looking up symbols, register
    values, routine calls, breakpoints, and so on.

    Example:

    DBG_2> DO/PROCESS=(%VISIBLE_PROCESS,%NEXT_PROCESS) -
    _DBG_2> (EXAMINE X)