~T tagged messages
~t \fIEXPR\fP messages addressed to \fIEXPR\fP
~U unread messages
+~u message is addressed to a subscribed mailing list
~v message is part of a collapsed thread.
~x \fIEXPR\fP messages which contain \fIEXPR\fP in the \(lqReferences\(rq field
~z \fIMIN\fP-\fIMAX\fP messages with a size in the range \fIMIN\fP to \fIMAX\fP