Value	Description
x	Matches the character x.
.	Match any character.
^	Specifies beginning of line.
$	Specifies end of line.
[xyz]	A character class. In this case, the pattern matches either x, y, or z.
[abj-oZ]	A character class with a range. This pattern matches a, b, any letter from j through o, or Z.
[^A-Z]	A negated character class. For example, this pattern matches any character except those in the class.
r*	Zero or more r's, where r is any regular expression.
r+	One or more r's, where r is any regular expression.
r?	Zero or one r, where r is any regular expression.
r{2,5}	From two to five r's, where r is any regular expression.
r{2,}	Two or more r's, where r is any regular expression.
r{4}	Exactly 4 r's, where r is any regular expression.
"[xyz]\"images"	The literal string [xyz]"images"
\X	If X is a, b, f, n, r, t, or v, then the ANSI-C interpretation of \x; Otherwise, a literal X. This is used to escape operators such as *.
\0	A NULL character.
\123	The character with octal value 123.
\x2a	The character with hexadecimal value 2a.
(r)	Matches an r; where r is any regular expression. You can use parentheses to override precedence.
rs	The regular expression r, followed by the regular expression s.
r|s	Either an r or an s.
#<n>#	Inserts an end node causing regular expression matching to stop when reached. The value n is returned.