+.Sh PATTERNS
+A
+.Em pattern
+consists of zero or more non-whitespace characters,
+.Sq *
+(a wildcard that matches zero or more characters),
+or
+.Sq ?\&
+(a wildcard that matches exactly one character).
+For example, to specify a set of declarations for any host in the
+.Dq .co.uk
+set of domains,
+the following pattern could be used:
+.Pp
+.Dl Host *.co.uk
+.Pp
+The following pattern
+would match any host in the 192.168.0.[0-9] network range:
+.Pp
+.Dl Host 192.168.0.?
+.Pp
+A
+.Em pattern-list
+is a comma-separated list of patterns.
+Patterns within pattern-lists may be negated
+by preceding them with an exclamation mark
+.Pq Sq !\& .
+For example,
+to allow a key to be used from anywhere within an organisation
+except from the
+.Dq dialup
+pool,
+the following entry (in authorized_keys) could be used:
+.Pp
+.Dl from=\&"!*.dialup.example.com,*.example.com\&"