A320 INITIATES WRONG STAR FOR OAK AT FL190.

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WHILE DSNDING THROUGH FL190 TO 13000 FT ON THE MARVN ONE (PXN.MARVN1) ARR INTO OAK; THE ZOA CTLR ASKED US IF WE WERE FLYING THE MARVN ONE ARR TO WHICH WE REPLIED IN THE AFFIRMATIVE. HE THEN CLRED US DIRECT TO THE BORED INTXN ON THE PANOCHE TWO (PXN.PXN2) ARR. WE THINK THE PREVIOUS CTLR FROM ZLA; BEFORE THE HDOF TO ZOA; MAY HAVE POSSIBLY RECLRED US TO OAK VIA THE PANOCHE TWO ARR; A CHANGE FROM OUR ORIGINAL MARVN ONE STAR. WE MAY HAVE NOT CAUGHT THE CHANGE DUE TO A POSSIBLE AMBIGUITY IN THE LAX CTLR'S CLRNC PHRASEOLOGY WHICH; TO THE BEST OF MY FO'S AND MY RECOLLECTION; SOUNDED LIKE: 'YOU ARE CLRED TO OAK VIA PANOCHE AND THE ARR' WHICH WAS READ BACK BY US AND INTERPRETED AS JUST A RECONFIRMATION OF THE ORIGINAL STAR OF MARVN ONE. CONTRIBUTING TO THE AMBIGUITY IS THAT BOTH STARS START AT PXN VOR. THE MARVN ONE IS OUTBOUND ON THE 328 DEG RADIAL AND THE PANOCHE TWO IS OUTBOUND ON THE 301 DEG RADIAL. THERE WAS NO APPARENT ISSUE WITH THE ZOA CTLR; HE JUST CLRED US TO BORED INTXN FOR THE NEW ARR. WE ARE JUST EXPRESSING DOUBT OVER THE PREVIOUS CTLR'S POSSIBLE AMBIGUOUS PHRASEOLOGY. FMS EQUIPPED ACFT CAN SOMETIMES HAVE A NAV INTERFACE THAT IS NOT VERY TRANSPARENT TO THE CREW. COMBINE THIS WITH CTLR PHRASEOLOGY AND THE EXPECTATIONS OF THE FLT CREW TO FLY A FILED STAR THAT IS THE NORM AND 2 DIFFERENT STARS THAT SHARE A COMMON INITIAL FIX (PXN); IT IS EASY TO SEE THE POSSIBLE UNINTENDED CONSEQUENCES OF FLYING THE WRONG RADIAL. I RECOMMEND THAT WHEN CTLRS ISSUE UNEXPECTED CHANGES TO A STAR IN THIS FAST-PACED DYNAMIC ATC ENVIRONMENT; THAT THEY INCORPORATE THE WORD 'NOW' IN THE NEW CLRNC AS A CUE TO THE FLT CREWS THAT A CHANGE IS FORTHCOMING IN THE CLRNC. THEY SHOULD ALSO ADHERE TO STANDARD PHRASEOLOGY TO ELIMINATE AMBIGUITIES. AN EXAMPLE WOULD BE: 'YOU ARE NOW CLRED TO THE ABC ARPT VIA THE XYZ ARR.'