UNAUTH TKOF FOR WDB AS ACFT EQUIP PROB MALFUNCTION WAS IN DISAGREEMENT WITH THE MEL REQUIREMENTS.

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ON ARR IN OAK; ADVISED TO KEEP SAME ACFT. SHORTLY THEREAFTER; ADVISED TO CHANGE DESTS AND ACFT. NEW ACFT HAD MANY DMI'S (DEFERRED MAINT). CAREFULLY CHKED ALL AND WE DETERMINED FLT WAS LEGAL. DEPARTED THE RAMP AND DURING TAXI TO ACTIVE RWY; INITIATED A DELAYED ENG START ON ENGS #1 AND #4. WHEN #1 ENG REACHED MAX MOTORING; I PLACED START SWITCH TO IDLE BUT GOT NO LIGHT OFF. FOLLOWED THE ABNORMAL AND USED IGNITION SWITCH #1 SYS FOR #1 ENG TO START; AND ENG STARTED NORMALLY. PER POLICY; WE TAXIED TO A HOLDING AREA; CONTACTED THE COMPANY; RECEIVED A DMI NUMBER FOR THE ENG #1 SYS 2 SWITCH; MADE APPROPRIATE LOG ENTRIES; APPLIED PLACARDS; AND THEN PROCEEDED TO SEA-TAC NORMALLY. ON ARR SEA-TAC WE MADE OTHER LOG ENTRIES. THE NEXT DAY; I WAS REVIEWING MY LOG ENTRIES AND FOUND I HAD MISSED THE NOTE IN THE MEL THAT STATED THAT AN IGNITION SWITCH COULD BE DMI'ED BUT ONLY IF THE CORRESPONDING ENG ANTI-ICE VALVE OPERATED NORMALLY. AS LUCK (BAD LUCK) WOULD HAVE IT; THE #1 ENG HAD ITS ANTI-ICE VALVE STUCK IN TRANSIT AND DMI'ED AS WELL. IN OUR DESIRE TO COMPLY WITH FARS WE HAD CONSCIENTIOUSLY DELAYED THE FLT TO DMI THE IGNITION; BUT IN OUR HASTE; HAD NEGLECTED TO REVIEW CORRELATING INFO. FLT WAS NEVER OPERATED IN CONDITIONS WHERE NEITHER ENG HEAT NOR IGNITION FOR PURPOSES OF TURB WAS REQUIRED; BUT I FULLY UNDERSTAND THIS IS NOT THE POINT. THE PAPERWORK MUST COMPLY WITH OPS SPECS. AS A RESULT; I WILL NEVER ASSUME I AM SO FAMILIAR WITH A PROC THAT I CAN RELY ON MEMORY ALONE. ALWAYS GET THE BOOK OUT (WHICH WE DID) AND BE CAREFUL TO READ ALL CORRELATING CONDITIONS WHICH MUST BE MET (WHICH I MISSED).