In 2010, the Coalition for Innovative Media Measurement (CIMM), now an affiliate of the ARF, developed this lexicon in order to create a common language for media measurement for use industrywide. One of the project’s initial goals was to facilitate the integration of Return Path Data (RPD). This lexicon has since been updated in 2012, 2016 and now 2021, to emulate the expansion of industry terms related to converged and advanced TV. New platforms, technologies and devices as well as expanded ways to buy, sell and measure media, have resulted in a myriad of new and revised terms and definitions. This latest version, dubbed ARF + CIMM Lexicon 4.0, incorporates all of these advancements, maintaining the reference’s status as a single, reliable and comprehensive resource for the industry.