A regular expression is a pattern-matching technique used extensively in UNIX environments. You use regular expressions in Designer to specify pattern-matching strings for some of its functions. For example, you can use a regular expression to specify an index, a property, or a mask in a webMethods Query Language (WQL) statement. You can also use a regular expression to specify the switch value for a BRANCH step.

To specify a regular expression, you must enclose the expression between / symbols. When the server encounters this symbol, it knows to interpret the characters between these symbols as a pattern-matching string (that is, a regular expression).

A simple pattern-matching string such as /string/ matches any element that contains string. So, for example, the regular expression /webMethods/ would match all of the following strings: