+ <b>--exclude=(true|false|all|flag)</b>
+
+ A message is called "excluded" if it matches at least one tag
+ in search.tag_exclude that does not appear explicitly in the
+ search terms. This option specifies whether to omit excluded
+ messages in the search process.
+
+ The default value, <b>true</b>, prevents excluded messages from match-
+ ing the search terms.
+
+ <b>all</b> additionally prevents excluded messages from appearing in
+ displayed results, in effect behaving as though the excluded
+ messages do not exist.
+
+ <b>false</b> allows excluded messages to match search terms and appear
+ in displayed results. Excluded messages are still marked in the
+ relevant outputs.
+
+ <b>flag</b> only has an effect when <b>--output=summary</b>. The output is
+ almost identical to <b>false</b>, but the "match count" is the number
+ of matching non-excluded messages in the thread, rather than
+ the number of matching messages.