A DEP B767-300 FO TURNS OFF COURSE FROM THE SID DURING INITIAL CLB AFTER THE ACFT EXPERIENCES A MAP SHIFT JUST PRIOR TO TKOF FROM LFPG; FO.

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CDG; HEADING CHANGE DURING DEP. DEPARTING CDG RWY 26R; I NOTICED A MAP SHIFT WHILE IN POS; NOT SO WHILE #1 FOR DEP. I TOLD THE COPLT WHO WAS FLYING THE AIRPLANE THAT I WOULD MONITOR RAW DATA SINCE WE HAD A TKOF CLRNC. AFTER DEP WE HAD A TCASII WARNING IN YELLOW RIGHT OVER THE ACFT. I LOOKED OUTSIDE AND SAW NOTHING. WHEN I LOOKED BACK AT MY FLT INSTS I NOTICED THE CDI WAS 1 DOT TO THE L. I TOLD THE COPLT TO COME L A LITTLE BIT AND 3 SECONDS LATER THE CTLR SAID TURN L 10 DEGS. I BELIEVE THAT SINCE WE HAD A TCASII WARNING I BECAME MORE CONCERNED WITH THAT THAN FOLLOWING THE DEP RADIAL AT THE MOST CRITICAL TIME. SUPPLEMENTAL INFO FROM ACN 483871: ON TKOF FROM CDG LNAV WAS ENGAGED AT 400 FT AGL AND COMMAND BARS COMMANDED A SLIGHT CORRECTION TO THE R. AS SOON AS I DID WE GOT THE TCASII TA AND HAD VISUAL CONTACT WITH AN ACFT THAT TOOK OFF ON THE PARALLEL RWY. AT THE SAME TIME THE CAPT CHKED THE RAW DATA AND TOLD ME I WAS SLIGHTLY R OF THE RADIAL. I WAS ALREADY IN THE TURN BASED ON THE CAPT'S INFO; AND THERE WAS NO FURTHER COMMENT FROM THE CTLR. THE MORAL OF THE STORY IS TO MAKE SURE THE FMS IS GIVING YOU ACCURATE INFO; BEFORE DOING WHAT IT SAYS. CHK THE RAW DATA FIRST.