The {R:0} contains the entire matched URL path, the {R:1} contains whatever was captured in the pattern within a first capture group. In case of wildcard patterns, each "*" symbol creates a capture group: for example if you had a pattern as " *bar*.aspx " and requested foobargoo.aspx...

Hi, please take a look to the following two articles, they will tell you what it means and how to use it: http://learn.iis.net/page.aspx/465/url-rewrite-module-configuration-reference/ (section "Using back-references in rewrite rules") http://learn.iis.net/page.aspx/500/testing-rewrite-rule...