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

       /RECORD_BLOCKING
       /NORECORD_BLOCKING

    Determines whether the symbiont can concatenate (or block
    together) output records for transmission to the output device.
    If you specify the /NORECORD_BLOCKING qualifier, the symbiont
    sends each formatted record in a separate I/O request to the
    output device. For the standard OpenVMS print symbiont, record
    blocking can have a significant performance advantage over
    single-record mode.