Langsamfahrsignale
Langsamfahrsignale = Slow travel signal (speed limit)
There are several plates to display speed limits, of two basic types: signs showing the maximum speed and, where the speed limit drops, advance warning signs.
The Lf1, Lf4 and Lf6 plates are advance warning boards, while the Lf2, Lf5 and Lf7 announce the start of speed limits. The Lf3 plate marks the end of temporary speed limits, but the end of a permanent speed limit was not usually shown.
Changes as of 2007:
Lf4/Lf5 are obsolete and are being replaced by Lf6/Lf7;
An increase in speed limit will now always be shown by a Lf7.
Read more about this topic: German Railway Signalling