+.Ss Restricted character set
+For security reasons, in particular to prevent cross site scripting
+attacks, some strings used by
+.Nm
+can only contain the following characters:
+.Pp
+.Bl -dash -compact -offset indent
+.It
+lower case and upper case ASCII letters
+.It
+the ten decimal digits
+.It
+the dash
+.Pq Sq -
+.It
+the dot
+.Pq Sq \&.
+.It
+the slash
+.Pq Sq /
+.It
+the underscore
+.Pq Sq _
+.El
+.Pp
+In particular, this applies to the
+.Ev SCRIPT_NAME ,
+to all manpaths, and to all architecture names.