first character after the "[" is "^", the class matches any character not
in the list. Within a list, the "-" character is used to specify a
range, so that C<a-z> represents all the characters between "a" and "z",
-inclusive.
+inclusive. If you want "-" itself to be a member of a class, put it
+at the start or end of the list, or escape it with a backslash. (The
+following all specify the same class of three characters: C<[-az]>,
+C<[az-]>, and C<[a\-z]>. All are different from C<[a-z]>, which
+specifies a class containing twenty-six characters.)
Characters may be specified using a metacharacter syntax much like that
used in C: "\n" matches a newline, "\t" a tab, "\r" a carriage return,