VMS Help MONITOR, MONITOR, Command Qualifier Descriptions, /BY_NODE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BY_NODE
       /NOBY_NODE

    Specifies that performance class data in a multifile summary be
    displayed as a single column of AVERAGE statistics for each node.

    The /BY_NODE qualifier displays data in a multifile summary. If
    you specify only one input file, MONITOR ignores the /BY_NODE
    qualifier because you are not performing a multifile summary.