Library /sys$common/syshlp/dtehelp.hlb SPAWN, /INPUT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /INPUT=filespec

    Specifies an input file containing one or more DCL commands to be
    executed by the spawned subprocess. File type defaults to COM and
    no wildcards are allowed in the file specification.  Once
    processing of the input file is complete, the subprocess is
    terminated.  If both a command string and the /INPUT qualifier are
    specified, the specified command string executes before additional
    commands are obtained from the /INPUT qualifier. If neither is
    specified, SYS$INPUT is assumed (in which case a SPAWN/NOWAIT
    command is aborted if Ctrl/Y is pressed to abort something running
    in your parent process).