HAWKER 800 FLT CREW DOES NOT MEET A XING RESTR.

Narrative

WE WERE ON A FLT FROM LAX TO HWD. I WAS THE SIC AND THE PF. WE HAD BEEN CLRED FROM THE GMN VOR DIRECT TO THE PNX VOR. CTR ISSUED US A DSCNT TO CROSS 10 MI SE OF THE PNX VOR AT FL200. THE CAPT; AS PNF; ENTERED THE XING RESTR INTO THE FMS AS I BEGAN OUR DSCNT FROM FL280. THE CTLR HAD USED SLIGHTLY VAGUE LANGUAGE IN ISSUING THE CLRNC. ('CROSS 10 MI THIS SIDE OF PNX AT FL200' OR 'CROSS 10 MI FROM PNX AT FL200'.) I HAD UNDERSTOOD THIS TO MEAN 10 MI SE OF PNX. THE CAPT I LATER LEARNED HAD INTERPED THIS TO MEAN CROSS 10 MI NW OF PNX AT FL200. THIS WAS MY FIRST TRIP IN THIS ACFT AND THE FMS WAS A TYPE I HAD NEVER USED BEFORE. I HAD NO KNOWLEDGE OF HOW TO OPERATE IT AND HAD DIFFICULTY GETTING INFO FROM THE DISPLAYS. AS A RESULT WHEN THE CAPT ENTERED THE XING RESTR; I ASSUMED HE HAD ENTERED IT CORRECTLY AND THAT HE HAD INTERPED THE POS OF THE XING RESTR AS I HAD. AS WE PASSED OVER THE XING RESTR POINT BTWN FL215 AND FL210(BTWN 1000 FT AND 1500 FT HIGH) THE CTLR INFORMED US THAT WE HAD BEEN CLRED TO CROSS 10 MI SE OF PNX AT FL200 AND INQUIRED AS TO WHY WE HAD NOT MADE THE RESTR.