VMS Help ATTACH, Qualifier, /IDENTIFICATION  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /IDENTIFICATION=pid

    Specifies the process identification (PID) of the process to
    which terminal control will be transferred. Leading zeros can be
    omitted. The /IDENTIFICATION qualifier is incompatible with the
    process-name parameter.

    If you omit the /IDENTIFICATION qualifier, you must specify a
    process name.