+The
+.B \-header
+switch control whether
+.B mhshow
+will print a message separator header before each message that it
+displays. The header format can be controlled using
+.B \-headerform
+to specify a file containing
+.IR mh\-format (5)
+instructions. A copy of the built-in default
+headerform can be found in %nmhetcdir%/mhshow.header, for reference.
+In addition to the normal set of
+.IR mh\-format (5)
+instructions, a "%{folder}" escape provides a
+string representing the current folder.
+.PP