Library /sys$common/syshlp/sysgen.hlb SHARE, /INITIALIZE, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 MPMn

    Specifies the number on the front panel of the multiport memory
    unit being connected.

 MPM-name

    Specifies the name by which the multiport memory unit is
    to be known to systems using it. The MPM-name is a 1 to 15
    alphanumeric character string that may contain dollar signs ($)
    and underscores (_).