IFF Mark II
... that the RAF's IFF Mark II was the first operational identification friend or foe system?
... that the <a href="./Royal_Air_Force" id="mwBjs" rel="mw:WikiLink" title="Royal Air Force">RAF</a>'s <b id="mwBjw"><a href="./IFF_Mark_II" id="mwBj0" rel="mw:WikiLink" title="IFF Mark II">IFF Mark II</a></b> was the first operational <a href="./Identification_friend_or_foe" id="mwBj4" rel="mw:WikiLink" title="Identification friend or foe">identification friend or foe</a> system?