Messerschmitt Parts Drawings Question

[crawdad]

Hello All,

I'm trying to interpret some Messerschmitt Me 109 parts drawings and was hoping somebody more knowledgeable could give me a few pointers.

Here are the questions:

1) Tolerances. On most dimensions, there are none and no tolerances in the title block. Does someone across the pond (or anywhere else) know what German practice was in this regard? Did the Germans have an industry-wide standard for tolerances or one peculiar to Messerschmitt?

2) The meaning of the phrase "Durchzüge nach Werkzeug Nr. 3 MeN 50715".
Babelfish gave me "through courses after tool nr. 50715" which doesn't tell me a lot.


3) The meaning of the phrase "BfN 13855". What does BfN stand for? "Bayerische Flugzeug Nummer"? The number of what?

All this information came off the same drawing.

Thanks for any hints.

Ray Crawford