I copied this from a Pakistan Defense website page. It has to do with the missiles:
Fox is a brevity code used by NATO pilots to signal the simulated or actual release of an air-to-air munition or other combat function, with a number added to the end of Fox to describe the primary type of sensors the launched munition possesses such as Semiactive radar-guided missile, such as an AIM-7 Sparrow or Skyflash (Fox-1) , Infrared-guided missile, such as an AIM-9 Sidewinder or AIM-132 ASRAAM (Fox-2) and Active radar-guided missile, such as an AIM-120 AMRAAM or AIM-54 Phoenix (Fox-3).
I copied this from a Pakistan Defense website page. It has to do with the missiles: Fox is a brevity code used by NATO pilots to signal the simulated or actual release of an air-to-air munition or other combat function, with a number added to the end of Fox to describe the primary type of sensors the launched munition possesses such as Semiactive radar-guided missile, such as an AIM-7 Sparrow or Skyflash (Fox-1) , Infrared-guided missile, such as an AIM-9 Sidewinder or AIM-132 ASRAAM (Fox-2) and Active radar-guided missile, such as an AIM-120 AMRAAM or AIM-54 Phoenix (Fox-3).