VMS Help System Services, $MOUNT, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 itmlst

    OpenVMS usage:item_list_3
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    Item list specifying options for the mount operation. The itmlst
    argument is the address of a list of item descriptors, each of
    which specifies an option and provides the information needed to
    perform the operation.

    The item list must include at least one device item descriptor
    and is terminated by a longword value of 0.

    Refer to the OpenVMS System Services Reference Manual to view the
    item code diagram and descriptor fields table.