Can we make isoglosses?

[Helmut Winkler]

Examples of P/B shifting can be found in some early heraldic chronicles where place names now ending in -burg were written as -purg.

What about the other end of 'pox',  -  the 'X' sound? Besides just -x, aren't there several other possibilities like -cks or -ckx that were used?

It is really  '(eines) Bockes Leber', which is spoken 'Bocks' which is the same sound as an x