# Regular Expressions

Regular expressions are powerful searching tools and take various syntax delimiters to aid in searching.

Expression | Description
^ | Specifies the start of a path. Used as the first item within brackets, specifies any AS number except the set specified.
$ | Specifies the end of a path.
{ | Specifies the start of an AS_SET.
} | Specifies the end of an AS_SET.
( | Specifies the start of an AS_CONFED_SET or AS_CONFED_SEQ.
) | Specifies the end of an AS_CONFED_SET or AS_CONFED_SEQ.
. | Matches any single character.
.* | Matches 0 or more of any characters.
.+ | Matches 1 or more of any characters.
_ | Matches 0 or 1 instance of any punctuation character.
[] | Specifies a set of characters.
- | Specifies a wide range of AS numbers.