--- a/discussion.roff	Wed Jul 11 09:58:18 2012 +0200
+++ b/discussion.roff	Wed Jul 11 10:13:54 2012 +0200
@@ -1066,10 +1066,15 @@
 At the time of writing, no more than 4 visible switches and 1 hidden switch
 have remained in mmh's
 .Pn send .
-(These numbers include two generic switches,
+These numbers include two generic switches,
 .Sw -help
 and
-.Sw -Version .)
+.Sw -Version .
+Hidden switches are ones not documented.
+In mmh, 12 tools have hidden switches.
+9 of them are
+.Sw -debug
+switches, the other 6 provide special interfaces for internal use.
 .P
 The figure displays the number of switches for each of the tools
 that is available in both nmh and mmh.