The SET EVENT command establishes the collection of event
    markers for a specified event when you execute program
    locations associated with that event. An event marker is a data
    record written to the performance data file to mark that some
    significant event has occurred during program execution. You
    determine what events are significant and what names to assign to
    those events.

    Event markers segment the performance or coverage data so that
    data can be associated with different phases or time periods
    of program execution. The Analyzer uses event markers to filter
    performance or coverage data so that only the data associated
    with a certain event or time period is tallied in histograms and
    tables. Each data point in the data file is associated with the
    event name of the most recent event marker that precedes it in
    the data file.

    When you enter a SET EVENT command, you must specify the name
    of the event you wish to define. You must also specify the node
    specifications to associate with that event. The Collector places
    a breakpoint on each such location and, when the breakpoint is
    reached, writes an event marker for that event to the performance
    data file.

    If you enter the SET EVENT command before entering a SET DATAFILE
    command, the Collector establishes a default data file. The
    default data file has the same file name as your program's
    executable image file and a file type of PCA.

    You can use one event marker per program location. Multiple
    program locations are allowed for each event name.