NOTE: As of 6/21/2012, the source code has moved to the Chromium repository. The instructions in the wiki have been updated.
The RLZ project is a library for grouping promotion event signals and anonymous user cohorts.
Client applications with the RLZ library can use explicit cohort tagging to manage promotion analysis. A client application with a particular tag can transmit that tag as it chooses for payments and analysis purposes. As an example, the RLZ parameter "rlz=1T4AAAA_enUS202" indicates the client application is Toolbar version 4, distributed with AAAA software bundle, English version, to a US user in December 2006. This empowers computation of metrics broken down into useful dimensions.
Find out more about how to read RLZ strings, how the code works in general, and how it is used in the Google Chrome web browser.