Lexology published an interesting article by Tanja Hogh Holub and Tilmann Lührig which discusses the registration of German trademarks, some important facts and circumstances that need to be taken into account when someone wants to register a national mark in the county.
One interesting fact is that unregistered trademarks in Germany have similar protection as registered one but with some specifics. For instance, an unregistered trademark with a regional reputation has protection only within the relevant region. In this case, the trademark owner’s legal remedies are also limited only to that area and he can’t prohibit a third party’s use in outside that area.
In addition, certification trademarks are not subject to protection in Germany.
More information here.