https://www.aesip.army.mil/irj/portal 1. Usable On Code (UOC) Information Usable On Code (UOC) - the user should be aware that the model M1097 series vehicle UOC is "HVY". Navigation through the Interactive Electronic Technical Manual (IETM) by specific model of HMMWV series vehicle is possible through the incorporation of UOC's, which will filter menu options and display information based on model HMMWV series vehicle selected. 2. Precedence This HMMWV Interactive Electronic Technical Manual (IETM) TM 9-2320-280-13&P takes precedence over any other publication.