Regular Expression Filter

The Regular Expression Filter employs power and flexibility of regular expressions, but is a rather complex skill to master.

The following is an quote from Wikipedia article on Regex:

In computing, a regular expression (abbreviated as regexp or regex, 

with plural forms regexps, regexes, or regexen) is a string that 

describes or matches a set of strings, according to certain syntax 

rules. Regular expressions are used by many text editors and utilities 

to search and manipulate bodies of text based on certain patterns. 

Many programming languages support regular expressions for string 

manipulation. For example, Perl and Tcl have a powerful regular expression 

engine built directly into their syntax. The set of utilities (including 

the editor ed and the filter grep) provided by Unix distributions were 

the first to popularize the concept of regular expressions.

In-depth explanation of Regular Expression technology is far beyond of the scope of this manual. As a solution, you may find these links useful: