UNABLE TO DETERMINE FROM THE PDC CLRNC THEIR ACTUAL CLEARED ALT WHILE FLYING THE NSIGN RNAV SID FROM SLC; FO OF B737-700 SETS 10000 FT MSL IN THE ALT ALERT BASED ON 'PREVIOUS EXPERIENCE.' AN ALT BELOW THE MEA AND BARELY ABOVE THE TERRAIN ON THEIR ROUTE OF FLT. CAPTAIN ASSUMES THE DEP BRIEFING IS CORRECT.

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AS THE FO; I RECEIVED THE CLEARANCE FOR THE LEG FROM SLC TO CITY BY PDC. THE PDC CLEARANCE WAS DETAILED ENOUGH TO INCLUDE THE 230 KT AIRSPEED RESTRICTION; BUT DID NOT INCLUDE THE INITIAL CLEARANCE ALTITUDE. NEITHER THE CAPTAIN NOR I HAD FLOWN THE RNAV DEPARTURES OUT OF SLC BEFORE. WHILE I CAREFULLY BRIEFED THE ALTITUDE AND AIRSPEED RESTRICTIONS ASSOCIATED WITH THE NSIGN1 DEPARTURE DURING THE CLEARANCE BRIEFING; I DID NOT CHECK THE CLEARANCE ALTITUDE ON THE DEPARTURE PLATE. INSTEAD; I SET 10000 FT BASED ON PREVIOUS EXPERIENCE WITH THE OLDER DEPARTURES OUT OF SLC AND THE CAPTAIN MISSED MY ERROR. WE TOOK OFF FROM RUNWAY 34R AND PASSING 1500 FT AGL (APPROXIMATELY 5700 FT MSL) THE CAPTAIN; AS THE PILOT MONITORING; TOLD SLC DEPARTURE THAT WE WERE PASSING 5700 FT FOR 10000 FT. AT THAT TIME; SLC DEPARTURE CORRECTED US TO CLIMB TO FL230 IN ACCORDANCE WITH THE PUBLISHED DEPARTURE. UPON FURTHER REVIEW; THE DEPARTURE PLATE SHOWS THE HIGH TERRAIN ALONG OUR FLIGHT PATH TO BE AROUND 9300 FT AND THE MSA TO BE 11000 FT. WHILE THE ERROR AS I HAVE STATED ABOVE; IS MINE FOR NOT CHECKING THE CORRECT INITIAL CLEARANCE ALTITUDE ON THE DEPARTURE PLATE; I BELIEVE THAT IN THE INTEREST OF SAFETY THE INITIAL CLEARANCE ALTITUDE SHOULD HAVE BEEN INCLUDED IN THE PDC. PLEASE INCLUDE THE INITIAL CLEARANCE ALTITUDE IN THE PDC AS IS DONE AT MOST EVERY OTHER AIRPORT. I WILL NEED TO BE EVEN MORE DILIGENT WITH RNAV DEPARTURE BRIEFINGS.