AN ACR WDB CREW DSNDED THROUGH ITS ASSIGNED ALT TO AN 'EXPECT' ALT AS SHOWN ON THE STAR.

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ON DSCNT INTO LAX; ACR WDB FLT WAS CLRED TO FILMORE; SADDE 4 ARR. WE CROSSED 'SYMON' AT 12000 FT AND 280 KTS AS DEPICTED. I GLANCED AT THE ARR CHART AND SAW 'BAYST' AT 10000 FT. I BEGAN A DSCNT AFTER CONFIRMING THAT WITH THE CAPT. I BEGAN THE LEVEL OFF WHEN LAX APCH CTL ISSUED AN IMMEDIATE L TURN TO 070 DEGS. AT THE SAME TIME I WAS IN THE ACFT OF CHANGING MY COURSE SELECTOR TO 081 DEG SFO THE INBOUND RADIAL TO SANTA MONICA; VOR; AND SWITCHING MY VOR SELECTOR TO SMO. I BEGAN THE TURN TO L IMMEDIATELY. AS I SCANNED THE AIRSPD; ALT; AND VSI I NOTICED A TCASII TARGET TO OUR R AND ABOVE US. I LOOKED OUTSIDE BUT DID NOT SEE AN ACFT; SO I TIGHTENED MY TURN. I WAS MANUALLY FLYING THE ACFT. LAX APCH CTL THEN CLRED US TO 8000 FT AND DIRECT SMO VOR. WE CONTINUED APCH AND LANDED RWY 24R. AS WE ROLLED OUT THE TWR ADVISED THAT 'IN THE FUTURE WE SHOULD EXPECT 10000 FT OVER BAYST INTXN; BUT THIS TIME; NO HARM; NO FOUL.' CONTRIBUTING FACTORS WOULD BE: SOMEWHAT TIRED AFTER ANY TRANSPACIFIC; HAVING RECEIVED CLRNC TO 10000 FT EVERY TIME IN THE PAST; WE WERE HABIT PRONE. 'EXPECT' SHOULD BE MORE PROMINENT ON CHART. POSSIBLE CORRECTIONS: REMOVE ALTS FROM CHART; UNLESS THEY ARE MANDATORY. SINCE YOU ARE ALREADY AT 12000 FT AND 280 KTS; IT IS NOT DIFFICULT TO SLOW/DSND IF INSTRUCTED! WHY INCLUDE 'MAYBE'S' AND 'POSSIBLY'S' ON ARR PLATE. IT IS JUST BUSY WORK AND CLUTTERS UP THE ARR. SUPPLEMENTAL INFO FROM ACN 242453: AS WE APCHED SYMON; THE FO STATED 'WE ARE TO CROSS BAYST AT 10000 FT; RIGHT?' I GLANCED AT THE SADDE 4 ARR AND CONFIRMED THE 10000 FT WHICH WAS AN ERROR ON OUR PART (SADDE 4 STATES EXPECT 10000 FT AT BAYST).