ELV recognizes several categories of events for inclusion in (or
    exclusion from) various operations. The first major separation
    is between valid and invalid events. Then, within the category
    of valid events are selected and rejected events. Explanations of
    these categories follow.

    o  Valid
       Valid events can be read into an internal buffer; also, bit-
       to-text translation data can be produced for the header.
       For an event to be valid, the event body does not need
       to be translatable; in this case, the event is valid but
       untranslatable.

       -  Selected
          A selected event is one that is of particular interest
          to you. You select events by using a selection qualifier:
          /ENTRY, /INCLUDE, /NODE, /SINCE, and /BEFORE. The events
          that are selected according to the selection criteria are
          included in or excluded from a report.

       -  Rejected
          A rejected event is one that is not included in a report
          because the command line specifies one of the following:

          *  An interval: /ENTRY, /SINCE, or /BEFORE

          *  A filter: /INCLUDE, /EXCLUDE, /NODE, or /NONODE

          You can use the /REJECTED qualifier to include rejected
          events in a report. (By default, only selected events are
          included in a report.)

    o  Invalid
       An invalid event is one that cannot be read into an internal
       buffer or whose header cannot be translated. You can use the
       ELV command DUMP/INVALID to output invalid events to an output
       dump file for further examination.