SMA EXPERIENCED TAXIING EVENT AT CID ALLEGING LCL ATC TAXI PHRASEOLOGY IS BOTH CONFUSING AND INCOMPLETE.

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INCIDENT #1: IT WAS AFTER WORK; I WAS TIRED; AND IT WAS ONE OF THOSE DAYS WHEN I SHOULD NOT HAVE BEEN FLYING ALONE; BUT SINCE I HAD A CFI BUDDY ALONG AND NEEDED THE INST PRACTICE; THE SAFETY BASES WERE ADEQUATELY COVERED. AND I WAS NEW TO CID; HAVING JUST MOVED TO THE AREA. I OBSERVED THE FLAGS FLAPPING IN THE BREEZE NEAR THE HANGAR AND DECIDED (FIRST ERROR -- ASSUMPTION THAT WAS NEVER CONFIRMED NOR CHALLENGED) THAT WE'D BE USING RWY 13. GND CLRED US TO 'TAXI RWY 9 VIA TXWY C;' AND THAT WAS THE ENTIRE TAXI CLRNC. I HEARD THAT; BUT WAS THINKING RWY 13; AND WAS CONFUSED; BECAUSE TXWY C GOES FROM THE RWY 27 NUMBERS TO THE RWY 31 NUMBERS; AND RWY 31 IS THE SAME PAVEMENT AS RWY 13; SO I WENT TO THE RWY 31 NUMBERS. FORTUNATELY; I STAYED OFF THE RWY (LOTS OF KNOWLEDGE OF RWY INCURSIONS); AND AFTERWARDS; I WAS THINKING THE NEXT DAY; HOW COULD I HAVE GOTTEN SO CONFUSED? INCIDENT #2: FAST FORWARD SEVERAL WKS; AND I WAS IN A FRIEND'S AIRPLANE GIVING A BFR. SAME PARKING PLACE; AND WE WERE CLRED TO 'TAXI TO RWY 13 VIA CHARLIE.' THAT WAS THE ENTIRE CLRNC. MY STUDENT; WHO HAD BEEN FLYING FROM CID FOR YRS; ALSO GOT CONFUSED AND ALSO WENT TO THE RWY 31 NUMBERS. THE MAJOR COMMON CONTRIBUTING FACTOR; AS I SEE IT; WAS CID'S UNIQUE PRACTICE OF GIVING PARTIAL TAXI CLRNCS. THE CLRNCS AS GIVEN WERE NOT COMPLETE TAXI CLRNCS; AS ARE GIVEN AT ALL OTHER ARPTS; THEY ARE PARTIAL CLRNCS GIVING JUST THE INITIAL DIRECTION OF TAXI; AND THE PLT IS 'ASSUMED' TO FIGURE OUT THE REST OF THE CLRNC. AND SINCE ONE END OF TXWY C IS RWY 31/13; THE CLRNC IS EASILY MISINTERPED. IN THESE 2 EVENTS; THE SAME MISTAKE WAS MADE; AND THE ONLY APPARENT COMMON FACTOR WAS AN INCOMPLETE TAXI CLRNC ISSUED BY GND CTL. AND THERE ARE LOTS OF OTHER ASRS RPTS WHERE 'LCL CUSTOMS' HAVE CONTRIBUTED TO TAXI ERRORS AND RWY INCURSIONS. I HOPE YOU FOLKS WILL GIVE CID TWR A CALL AND SEE WHAT'S GOING ON. AFTER MY ERROR; I DOUBT THEY'D LISTEN TO ME.