VMS Help START, /QUEUE, Qualifiers, /BASE_PRIORITY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BASE_PRIORITY=n

    Specifies the base process priority at which jobs are initiated
    from a batch execution queue. By default, if you omit the
    qualifier, jobs are initiated at the same priority as the base
    priority established by DEFPRI at system generation (usually 4).
    The base priority specifier can be any decimal value from 0 to
    15.