Character Classes

[abc]	One of a, b, or c
[a-z]	A letter from a to z
[^abc]	Any letter appart from a, b, and c.
\t	The character tab
\n	The character newline
\r	The character carriage return
\a	The character alert
\f	The character form feed
\e	The character escape
\cx	The character control-x (a-z)
\d	Digit
\D	Non-digit
\s	Space
\S	Non-space