VMS Help SET, RMS_DEFAULT, Qualifiers, /SEQUENTIAL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SEQUENTIAL (default)

    Applies the multibuffer default to sequential file operations.
    The /SEQUENTIAL qualifier overrides values applied using either
    the /DISK, the /MAGNETIC TAPE, or the /UNIT RECORD qualifier.

    The /SEQUENTIAL qualifier is the default if you do not specify
    either the /RELATIVE or the /INDEXED qualifier.