Thanks Melanie!
that seems to answer most of it. I am fairly new to all of this and do spend a lot of time misunderstanding the datasheet :-) I spent a lot of time failing to write to bit 12 of the CONFIG1 register. I tried the following methods and failed:-

CONFIG1.12 = 0

CONFIG1=CONFIG1 & 10111111111111

CCPMX=0

Are any of the above valid but wrong in their numeric content because they did not work? Can you write to such a register from PBP or are we restricted to just the magic (and seemingly invisible in the manual) PBP defines?

A couple of words would be very much appreciated here :-)

all best and thanks for your reply

Maurice