LR25 FLT CREW IS CONFUSED WITH ATC CLRNC DEPARTING FROM LAS REF ALT CLRNC.

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THE REASON IN SUBMITTING THE FOLLOWING RPT IS TO BRING ATTN TO A POSSIBLE HAZARD WITH THE PRFUM RNAV 1 DEP AT LAS VEGAS INTL ARPT. WE FEEL THE PROB WAS MORE IN COM BREAKDOWN RATHER THAN THE PROC ITSELF. WE WERE FLYING A LEAR 25 WITH GPS. WE RECEIVED OUR ATC CLRNC THROUGH LAS VEGAS CLRNC DELIVERY ON 118.0; CLRED TO ELP VIA THE PRFUM RNAV 1 DEP DRK TRANSITION THEN AS FILED; CLB AND MAINTAIN 7000 FT AND SQUAWK. THEN WE CALLED GND TO OBTAIN TAXI CLRNC AND WERE CLRED TO TAXI AND HOLD SHORT RWY 19R. THEN WE WERE CLRED TO CROSS RWY 19R AND HOLD SHORT RWY 19L. THEN TAXI POS AND HOLD RWY 19L AND SHORTLY AFTER CLRED FOR TKOF. WE WERE THEN TOLD TO CONTACT LAS VEGAS DEP ON 125.9. WE CALLED AND SAID ACFT X AT APPROX ALT OF 6000 FT CLBING TO 7000 FT. AT 6000 FT WE STARTED TO DECREASE PWR TO LEVEL AT 7000 FT. PRIOR TO REACHING FIXIX; LAS VEGAS DEP SAID TO CLB TO FL190 AND WE READ BACK 'ACFT X CLB TO FL190.' AT THIS POINT; WE INITIATED OUR CLB TO FL190; THUS PASSING THROUGH ORIGINALLY ASSIGNED ALT OF 7000 FT. AFTER PASSING FIXIX AND PROCEEDING TO ROPPR; DEP THEN SAID COMPLY WITH SID RESTRS. WE READ BACK 'ACFT X COMPLY WITH SID RESTRS.' AT THIS POINT; WE WERE ALREADY AT APPROX 7800 FT AND TRYING TO STOP CLB. WE BEGAN OUR DSCNT BACK TO 7000 FT WHEN WE WERE NOTIFIED OF AN ALTDEV. THEN DEP SAID MAINTAIN 7000 FT AND SUBSEQUENTLY AUTH 8000 FT. DEP THEN GAVE US A PHONE NUMBER TO CALL LAS VEGAS ATC. WHEN WE LANDED IN EL PASO 1 1/2 HRS LATER; WE CALLED LAS VEGAS DEP. HE EXPLAINED WHY WE NEEDED TO CALL HIM ABOUT AN ALTDEV. HE SAID WE WERE CLRED TO FL190 AND THAT WE WERE TO COMPLY WITH RESTRS ON THE SID. WE UNDERSTOOD; HOWEVER; THAT WE WERE CLRED TO FL190 AND LATER WERE TOLD TO COMPLY WITH SID; THUS CAUSING THE PROB OF MISCOM. IF WE HAD NEVER BEEN TOLD TO CLB TO FL190 AND TO JUST COMPLY WITH THE SID; WE FEEL AS A FLT CREW THIS PROB WOULD NOT HAVE OCCURRED. WE TOLD HIM THIS AND HE AGREED THAT IT MAY HAVE NOT BEEN CLR AND HE SAID THAT WE WERE NOT THE FIRST ACFT TO EXPERIENCE THIS PROB. TO AVOID FURTHER PROBS; WE FEEL THAT DEP COULD HAVE GIVEN THE INSTRUCTIONS DIFFERENTLY; SUCH AS 'COMPLY WITH SID; MAINTAIN FL190.' THIS WOULD HAVE BEEN MUCH CLRER AND EASIER TO UNDERSTAND.