Not that Darrell needs it, but I feel compelled to jump in here and row his boat. To my knowledge, borrow/carry flag in the status reg is the same across ALL PIC's. It is not a compilier thing. It is a basic hardware reg no different then any other. It exists the same as W. That said, I believe it is cleared at POR, but it doesn't matter. it only has value directly after an addition or subtraction. Well it is also used on rotate R/L through carry, but PBP doesn't support that. Some devices even have 1 for borrow or carry between nibbles, but again only used during math.

So startup value makes no difference for the snippet in post 12 as it follows a math operation.