Library /sys$common/syshlp/scacp$help.hlb SHOW, TRACE, Qualifiers, /EVENT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /EVENT[=(event1,event2,...)]

    Enables tracing on specific events, which you can specify using
    wildcards. The default is all of the events that are in the trace
    buffer.

    Use the SHOW TRACE/CONTEXT command to display event names.