FLC OF AN MLG ACR ACFT FAILED TO FOLLOW THEIR PDC DURING DEP RESULTING IN ATC INTERVENTION.

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DEPARTING FROM LAS. COPLT WAS FLYING. WE WERE FLYING THE MEAD 8 SID AND HAD JUST PASSED 4000 FT AND WERE TURNING DIRECT TO BLD (RNAV) WHEN DEP CTL ASKED OUR HDG. I TOLD THEM WE WERE TURNING TO BLD. DEP CTL THEN INFORMED US (IN A NICE MANNER) THAT WE SHOULD BE FLYING A HDG OF 060 DEGS AS DIRECTED IN OUR PDC. WE TURNED BACK TO A 060 DEG HDG AND I DOUBLE-CHKED THE PDC. SURE ENOUGH; AT THE VERY BOTTOM WAS 'TURN R HDG 060 VECTOR MEAD 8.' I TOLD DEP CTL OF THE 060 DEG HDG ON THE BOTTOM OF THE PDC; BUT THAT IT WAS CONFUSING AND HE AGREED STATING THAT 'THEY WERE HAVING PROBS WITH THIS DEP CLRNC AND WERE TRYING TO SOLVE IT.' I ASKED IF THERE WAS A CONFLICT AND HE SAID; 'NO; BUT DURING BUSY TIMES THERE COULD BE.' SINCE THIS WAS THE FIRST TIME THAT BOTH THE COPLT AND I HAD BEEN TO LAS IN QUITE SOME TIME WE BOTH MISSED THE 060 DEG HDG ON THE PDC AND EVEN AFTER DISCUSSING THIS CLRNC WE STILL HAD QUESTIONS ABOUT IT. I SUGGEST THAT A PDC CLRNC LIKE THIS MIGHT READ: CLRED AS FILED LAS MEAD 8 -- EXCEPT; HDG 060 DEGS VECTORS PGS J-86; ETC.