What do these letters mean on this headlight switch

If you get a shop manual, which I've suggested 10,000 times on here, from MyMopar that question will be answered. That switch fits many years.

B1, B2, EG are the battery supply, one is for headlights ONLY and the other comes from the tail fuse and supplies tail/ park/ and the dash dimmer control

P is park

Learning to search for old threads is also 'not' a waste of time

Headlight switch - 75 Duster - Stumped...