A320 FLT CREW FAIL TO FOLLOW POMONA SID TRACK OUT OF ONT.

Narrative

AFTER TKOF ON RWY 26L; WE MADE OUR INITIAL CLB HDG 255 DEGS PER THE DEP DESCRIPTION. AFTER PASSING THE POMONA VOR WBOUND; SOCAL CALLED TO GIVE US A N HDG AND TO TELL US WE MISSED THE TURN TO THE VOR (POMONA). WE WERE THEN TOLD TO RE-INTERCEPT THE DEP RTE N OF THE VOR AND TO CALL THE SUPVR WHEN WE GOT TO OUR DEST. THIS NAV DEV WAS THE RESULT OF AN APPARENTLY ARBITRARY DIFFERENCE IN THE COMMERCIAL CHART FORMAT FOR THE ONT DEPS. ALL THE OTHER DEPS; INCLUDING ONES FROM OTHER SOCAL CTLED ARPTS; HAVE THE HDG AND RTE INFO TOGETHER. IN THIS INSTANCE; THEY WERE SEPARATED ON THE CHART. IN ADDITION TO THIS; THE PICTORIAL DEPICTION WAS MISLEADING IN THAT IT LOOKS LIKE A HDG IS REQUIRED UNTIL RADAR VECTORS ARE GIVEN TO INTERCEPT THE RTE N OF THE VOR; WHICH IS WHAT WE ENDED UP DOING. BOTH THE CAPT AND MYSELF INDEPENDENTLY REVIEWED THE DEP; AND THEN BRIEFED IT TOGETHER ACCORDINGLY. FOR BOTH OF US TO HAVE 'TAKEN THE BAIT' CLRLY INDICATED THAT THERE WAS TOO MUCH AMBIGUITY ON HOW THE CHART WAS BOTH WRITTEN AND DEPICTED.