GLOSSARY (cent) TM 1-1520-238-T-10 GLOSSARY (cont) ABBR HDST HDU HI HMD HME HMS HOD HORIZ HORZ HP HP HR HSI HSY HTR HZ I/O I/P IAT IC ICS ID IDENT IF IFF IHADSS IHU ILK ^DEFINITION— headset helmet display unit high helmet-mounted display hellfire missile electronics helmet mounted sight heads out display horizontal horizontal hydraulic power hydraulic manifold/control valve heater IVD HYD horizontal situation indicator ±10v analog heater hydraulic hertz (cycles per second) in/out identification and position interlock arm missile image auto tracker IAM intercommunications intercommunication system identification identification intermediate frequency identification friend or foe integrated helmet and display sight system integrated helmet unit interlock ABBR ILLUM INBD INC IND INOP INST INSTR INT INTEG INTLK INTMD INTR IR ISOL J JAM JETT JMR JTSN K K KT L L L L-R LAT LATL LCHR DEFINITION illumination inboard increase indicator inoperative instrument instrument intermediate interrogator interlock intermediate interior infrared isolation indirect view display jack/receptacle jammer jettison jammer jettison relay thousand knots actuator/solenoid valve coil left left-right lattitude lateral launcher Glossary-5