Webtrends Analytics 9 Adminstration Guide, November 2012
You can use regular expression syntax to specify patterns found in log file records when configuring various Webtrends Analytics 9 advanced features.
For example, you can use them to match URL parameters or page names when configuring Content Groups, custom reports, and URL Rebuilding definitions. Regular expressions are useful because they provide more flexible and powerful pattern matching than you can achieve with wildcards.
In general, regular expressions are not as resource-efficient as absolute definitions, and the more complex the regular expression, the more resources are allocated to matching. If you find that using complex regular expressions causes performance problems, keep in mind that regular expressions using beginning-of-string matching (^) and end-of-string matching ($) are the most efficient.
The regular expression syntax supported by Webtrends Analytics 9 may not be identical to the syntax used in other applications. You can verify your regular expressions using the Test button in dialog boxes that accept regular expressions.