VMS Help TCPIP Services, FTP, Copying Files, VMS Plus Mode  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    FTP performs fast file transfers between two OpenVMS systems (VMS
    Plus Mode).

    When FTP identifies file transfers between two OpenVMS hosts
    running DIGITAL TCP/IP Services for OpenVMS, it transfers files
    in large blocks, rather than small records. VMS Plus Mode greatly
    increases the transfer speed and preserves all Record Management
    Services (RMS) file attributes.

    FTP automatically disables VMS Plus Mode when your session is
    with a UNIX host or another OpenVMS host not running DIGITAL
    TCP/IP Services for OpenVMS.