The WiMAX Forum™ is a non profit trade association industry group with a different mission from the IEEE 802.16, ETSI HiperMAN or WiBro/Mobile WiMAX standards working groups.  The imperative of the IEEE and ETSI groups is to formulate the technology specifications.  The forum shoulders the task of incorporating the variations in the three specifications groups to ensure interoperability amongst them and to promote and market the technology and its adherents. 

Additionally, the forum regulates and defines the testing parameters for true WiMAX Certification™ of interoperable products.  The ultimate result is that both bodies are very collaborative, but with clearly delineated responsibilities.