From memory it was sequences as:
Pickup 1 - both coils
Pickup 1 - single coil
Pickup 2 - both coils
Pickup 2 - single coil
Pickup 1 + 2 - both coils
Pickup 1 + 2 - single coils
It didn't make the most sense. I found that any amp or EQ setting that favoured the humbucker settings, say, would underperform with the single coils. The switch is quite a flimsy unit when you get a look under the hood, which was another motivating factor. Mine is now wired like a Telecaster.