B737 CREW INBOUND TO LAS ON SKEBR ARR BECOME CONFUSED WITH AMENDED CLRNC FOR RWY 25L.

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WHILE FLYING THE SKEBR ARR TO LAS; WE WERE JUST OUTSIDE CLARR INTXN AT 13000 FT; 250 KIAS (LNDG RWY 25L AT LAS). APCH THEN SAID 'COMPANY XXXX CLRED SKEBR ARR EXCEPT MAINTAIN 8000 FT.' AFTER DISCUSSING THIS WITH MY FO; WE CONCLUDED THAT WE WERE CLRED TO 8000 FT. AT 11700 FT; APCH CLRED US TO 11000 FT. THE REMAINDER OF THE ARR WAS NORMAL. I CALLED APCH VIA TELEPHONE UPON ARR AT LAS AND WAS TOLD THAT THE CLRNC MEANT COMPLY WITH ALL RESTRS ON ARR UNTIL KIMME WHICH WAS TO BE CROSSED AT 8000 FT. THE CLRNC THAT WAS GIVEN TO US WAS VERY MISLEADING. BOTH THE FO AND I (WITH A COMBINED 30 YRS OF ACR FLYING) VIEWED THE CLRNC ONE WAY AND THE CTLR ANOTHER. THIS IS VERY DISTURBING CONSIDERING THIS IS COUPLED WITH THE NEW RNAV PROC; HIGH TERRAIN IN THE IMMEDIATE AREA; AND HIGH VOLUME OF TFC. IN DISCUSSION WITH THE CTLR; I SUGGESTED USING DIFFERENT VERBIAGE SUCH AS 'CLRED SKEBR ARR EXCEPT CROSS KIMME AT 8000 FT' BUT WAS TOLD THAT LONGER CLRNCS (MEANING AMOUNT OF WORDS USED) OVER A FULL DAY; CONSIDERING NUMBER OF FLTS WORKED; WOULD BE DIFFICULT. IT IS MY OPINION THAT THE CLRNCS NEED TO BE MORE SPECIFIC AND WE NEED BETTER COM WITH ATC ON WHAT IS TO BE EXPECTED. SUPPLEMENTAL INFO FROM ACN 558512: WE WERE FLYING THE SKEBR ARR TO LAS. WE WERE TOLD TO CROSS CLARR AT 13000 FT AND 250 KTS; WHICH WE DID. AFTER CLARR; WE WERE TOLD TO 'DSND VIA THE SKEBR ARR EXCEPT MAINTAIN 8000 FT.' AFTER A SHORT DISCUSSION WITH THE CAPT; WE CONCLUDED THAT 8000 FT IS THE NEW HARD ALT AND STARTED TO DSND. AT 11700 FT WE WERE TOLD TO MAINTAIN 11000 FT; WHICH WE DID. THE CTLR WANTED US TO MAINTAIN 8000 FT AFTER POVOC. WE ASSUMED 'EXCEPT' MEANT HE WANTED US AT 8000 FT. AFTER TALKING TO ATC ON THE PHONE; BOTH THE CAPT AND I WERE STILL CONFUSED. THE WORD 'EXCEPT' MEANT TO US THAT 8000 FT WAS OUR NEW ASSIGNED HARD ALT. APPARENTLY; THIS IS NOT THE CASE. THE ARRS AND DSCNTS INTO LAS HAVE BECOME MORE COMPLICATED. IT SEEMS INSTRUCTIONS ARE MORE VAGUE LEAVING US GUESSING WHAT CTLRS WANT. IF THE CTLR SAID 'DSND VIA THE SKEBR ARR AND MAINTAIN 8000 FT AFTER POVOC;' I WOULD NOT BE WRITING THIS RPT. THOSE 2 SIMPLE WORDS 'AFTER POVOC' AND THERE WOULD BE A LOT LESS PAPERWORK. EITHER WE NEED TO BE TRAINED TO BETTER UNDERSTAND ATC INSTRUCTIONS OR ATC NEEDS TO BE MORE CLR IN WHAT THEY EXPECT. LAS HAS BECOME VERY FRUSTRATING.