"Basic rules of the air" that would be the content of LuftVO.
This letter was to inform you, that there are proceedings aganinst you. They need to do that, because your name were given to them as PIC by the aircraft owner (or his delegate if it was leased).
There could be more details in the questionaire the owner/lessor replied to giving your name.
Otherwise you will have to wait for a questionaire to yourself or the ticket to know more.