B737-500 FLC; UNABLE TO USE ENTIRE RWY; MAKE OVERWT TKOF FROM INTXN. MISINTERP OF TEMPORARY PERFORMANCE DATA. ERROR ADMITTED.

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ANOTHER ACR ACFT TAXIED OFF THE EDGE ON THE RWY. THE TWR ASKED IF WE COULD TAKE OFF FROM TXWY K; BEING THAT WE WERE BEHIND THIS ACFT. OUR PERFORMANCE FLT MANUAL HAS TEMPORARY DATA FOR THAT ARPT; AND I USED THIS DATA IN MY PERFORMANCE COMPUTATIONS. I AM NEW AT THE COMPANY (2 MONTHS); AND THE ARPTS I HAVE FLOWN INTO UP TO THIS POINT HAVE NOT; OR VERY FEW; NEEDED TO USE TEMPORARY DATA. HOWEVER; I WAS SURE WE WERE OK FOR TKOF BECAUSE OUR TEMPORARY DATA IS FOR ARPTS WITH UNUSUAL SITS; LIKE CONSTRUCTION TO RWYS AND TXWYS; THEREFORE; THE FULL LENGTH OF CERTAIN RWYS WOULD NOT BE USEABLE. THE CAPT ASKED ME IF WE WERE OK TO USE TXWY K; AND I ASSURED HIM WE WERE. ON THE TKOF ROLL; IT WAS MY TKOF; I NOTICED AND FELT THE CAPT ADDING MORE THRUST. WE ROTATED ON SPD AND LIFTED OFF WITH APPROX 1500-2000 FT REMAINING. WHILE ENRTE TO OUR DEST; WE RECALCULATED AND REALIZED THAT WE HAD EXCEEDED OUR TKOF WT LIMIT FOR THAT RWY FROM TXWY K. I HAVE LEARNED A VERY VALUABLE LESSON FROM THIS EXPERIENCE. ALTHOUGH I FEEL VERY COMFORTABLE WITH OUR PERFORMANCE COMPUTATIONS; I REALIZE THAT ONE SMALL OVERSIGHT CAN MAKE A HUGE DIFFERENCE.