+ * If set to FALSE or FLAG then both notmuch_query_search_messages and
+ * notmuch_query_search_threads will return all matching
+ * messages/threads regardless of exclude status. If set to FLAG then
+ * the exclude flag will be set for any excluded message that is
+ * returned by notmuch_query_search_messages, and the thread counts
+ * for threads returned by notmuch_query_search_threads will be the
+ * number of non-excluded messages/matches. Otherwise, if set to
+ * FALSE, then the exclude status is completely ignored.
+ *