VMS Help LANCP, SET, ACP, Qualifiers, /ECHO  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /ECHO
       /NOECHO (default)

    Enables partial tracing of received and transmitted downline
    load messages (the first 32 bytes of the data portion of
    each message). Note that the last one or two MOP messages
    are displayed in full: the memory load message with cluster
    parameters, and the parameter load with transfer address message,
    where present in the load.

    The data is written to a log file SYS$MANAGER:LAN$node-name.LOG.

    To obtain the entire contents of each message, use the /FULL
    qualifier as follows:

    SET ACP/ECHO/FULL