GIV FLC ATTEMPTS TO CLARIFY 'DURESS' FLAP INDICATION WHILE TAXIING AT MKE; REQUIRING THE PIC TO FURTHER RESOLVE THE ISSUE WITH TWR.

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AFTER LNDG AT MKE; WING FLAPS WERE LEFT FULLY EXTENDED DURING TAXI TO RAMP DUE TO SUSPECTED INDICATION ERROR WHICH WE WISHED TO CONFIRM AFTER SHUTDOWN. KNOWING THAT TAXIING WITH THE FLAPS FULLY EXTENDED IS USED AS A SIGNAL OF HIJACKING IN SOME PARTS OF THE WORLD; I INSTRUCTED MY FO TO INFORM GND CTL THAT WE WERE NOT UNDER ANY DURESS. HE XMITTED WORDS TO THE EFFECT OF 'THE FLAPS ARE DOWN; THEY ARE ON PURPOSE.' I WAS CONCERNED THAT HIS TERMINOLOGY MIGHT CAUSE CONFUSION; BUT THE TONE OF THE CTLR'S REPLY (WHICH I TOOK TO MEAN HE UNDERSTOOD THAT WE WERE UNDER NO DURESS); THE FACT WE WERE SQUAWKING OUR ASSIGNED CODE AND NOT 7500 AT A FACILITY WHICH MONITORS CODES ON THE GND; AND COCKPIT WORKLOAD LED ME TO DROP THE MATTER. TALKING TO THE TWR ON THE PHONE FROM THE FBO; I LEARNED WE HAD CAUSED CONFUSION AMONG THE CTLRS; ALTHOUGH NOT SO MUCH THAT THEY TOOK ANY ACTION. STILL; OUR POOR PHRASEOLOGY LED TO INCREASED WORKLOAD OF TWR PERSONNEL AND COULD HAVE LED TO AN UNNECESSARY AND POTENTIALLY HAZARDOUS SECURITY RESPONSE. I SHOULD HAVE BEEN VERY SPECIFIC TO MY FO AS TO WHAT I WANTED HIM TO XMIT. IF I HAD TOLD HIM 'TELL GND THAT WE ARE TAXIING WITH OUR FLAPS EXTENDED DUE TO A MECHANICAL MALFUNCTION' THERE WOULD HAVE BEEN NO CONFUSION. WHILE THE FAR'S AND AIM COVER THE AIRBORNE USE OF THE 7500 XPONDER CODE; THERE IS LITTLE TO NO GUIDANCE FOR COVERT SIGNALING ON THE GND IN CASE OF HIJACK. IN THE CURRENT ENVIRONMENT; FAA NEEDS TO THINK BEYOND THE 7500 CODE IN HIJACK SITS.