Got it from my Aus R32 owner's manual. I don't see why it would be any different for the 33... will scan up the page when I get a chance if you want
I only discovered this when I had the light come on (and stay on until the car cooled) at the track last year and the oil pressure gauge was still up. Stressed I'd done a big end, but sounded fine after cooling.
I actually didn't go to the manual then, but after removing the 3 centre gauges and replacing with 3 defi gauges subsequently, the light stayed permanently on. From here I suspected that the oil temp would trigger the light too, so I checked the manual and that's what it said
sorry for the ramble