I wonder what "bf" stands for? Like "me" for Messerschmitt, or is it just a preferred letter?
Bayerische Flugzeugwerke
Formed in Augsburg in 1926. Willy Messerschmitt worked for them as a designer.
The 109 was designed by Willy when he worked for BFW. In 1938 the name changed from Bayrische Flugzeugwerke to Messerchmitt AG.