Webtrends Analytics 9 Adminstration Guide, November 2012
Each entry in the web activity file contains a field that references the URL of the page or file that was accessed. Webtrends Analytics 9 uses this field to track activity on the web site and counts each unique URL as a separate page or file.
However, some web server plug-ins or shopping cart software add a unique string to the page name in order to track visitors and their shopping carts. In these situations, every hit to such a page appears in the file as a unique URL (containing the ID of the visitor), which prevents Webtrends from counting of hits to these pages accurately.
URL search and replace allows you to delete specific identifiers from URLs or replace all unique identifiers with a common string. Doing so restores accuracy to page counts, makes your reports more informative, and avoids some out of memory conditions when the number of unique IDs is extremely high.
You can also use URL search and replace to analyze and report on URLs differently than they were captured in the web activity file. You might do this to report on all pages from a certain directory as hits to the same page, forcing the pages into a group. Grouping pages using URL search and replace differs from content groups because content group definitions only apply to content group reports, whereas a URL search and replace definition applies to all reports.