VMS Help MONITOR, MONITOR, Parameter  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 classname[,...]

    Specifies the class of performance data to be monitored. To
    monitor all classes, specify the ALL_CLASSES parameter. When you
    specify several classes, separate the classname parameters with
    commas or plus signs. You cannot specify the CLUSTER class name
    with any other class name. Cluster monitoring functions require
    that DECnet for OpenVMS be installed.

    The MONITOR and SET DEFAULT commands accept the same qualifiers.
    As these qualifiers follow the standard rules of DCL grammar
    as specified in the OpenVMS DCL Dictionary, you can abbreviate
    any qualifier or keyword as long as the abbreviation is not
    ambiguous. Use the asterisk and the percent sign as wildcard
    characters unless otherwise noted.