Corporate aircraft departing LAX on the LOOP 6 SID initiated a left turn at 415 FT but were re-cleared by ATC to continue on the 250 heading; reporters noting confusing language on the chart.

Narrative

We were cleared to depart LAX via the 'LOOP SIX' departure (LOOP6.LAX) from Runway 25R. The LOOP Six for Runway 25R reads as follows (verbatim): Climb heading 250 to cross SMO R-160 at or below 3;000 FT (ATC)/at or above 415 FT; then turn LEFT heading 235. Expect RADAR vectors to cross LAX at or above 10;000 FT (ATC)/at or above 3;400 FT. Both the PIC and I misinterpreted this SID. We thought that what was expected of us is to turn to a 235 heading out of 415 FT while crossing the SMO R-160 at or below 3;000 FT on that 235 heading. As such; I initiated a left turn at 415 FT to a 235 heading. LAX Tower immediately called us and told us to return to a 250 heading; which I immediately complied with. A few seconds later the Tower Controller directed us to turn left to a 235 heading and handed us over to LAX Departure Control. No traffic alert/conflict had occurred. The reminder of the flight went uneventful. Suggestions; if in doubt what it is that we are supposed to do per a SID; call Clearance Delivery and clarify it! However; the problem in our particular scenario was that we had no doubt as to how we read the SID procedure. We both were in agreement that a turn to a 235 heading was supposed to be initiated at 415 FT.