MC_(AGE_GREATER), MC_(AGE_LOWER),
MC_(AGE_GREATER_HOURS), MC_(AGE_LOWER_HOURS),
MC_(NEWSGROUPS), MC_(NOT_NEWSGROUPS),
+ MC_(MESSAGEID), MC_(NOT_MESSAGEID),
MC_(INREPLYTO), MC_(NOT_INREPLYTO),
MC_(REFERENCES), MC_(NOT_REFERENCES),
MC_(SCORE_GREATER), MC_(SCORE_LOWER),