+.SS "Key-value output"
+Some commands (e.g.,
+.B STATS
+and
+.BR SERVINFO )
+produce output in the form of
+.IB key = value
+pairs, one per word. Neither the
+.I key
+nor the
+.I value
+contain spaces.
+.SS "Trace lists"
+Commands which enable or disable kinds of output (e.g.,
+.B TRACE
+and
+.BR WATCH )
+work in similar ways. They take a single optional argument, which
+consists of a string of letters selecting message types, optionally
+interspersed with
+.RB ` + '
+to enable, or
+.RB ` \- '
+to disable, the subsequently listed types.
+.PP
+If the argument is omitted, the available message types are displayed,
+one to an
+.B INFO
+line, in a fixed-column format. Column zero contains the key letter for
+selecting that message type; column one contains either a space or a
+.RB ` + '
+sign, if the message type is disabled or enabled respectively; and a
+textual description of the message type begins at column 3 and continues
+to the end of the line.
+.PP
+Lowercase key letters control individual message types. Uppercase key
+letters control collections of message types.