I don't have a translation, Alexander, but you can see exactly what a Feilnase is here:

Feilnase
In jedem Schließblech befindet sich eine rechteckige Öffnung, in die die Falle einrastet, wenn die Tür verschlossen wird. Da es selbst bei der besten Türmontage immer zu Toleranzen kommen kann, aufgrund derer die Falle im Schließblech zu viel Spiel hat (also bei Winddruck "scheppert"), sind die Öffnungen in den Schließblechen vielfach mit einer Ausbuchtung ausgestattet, der sog. Feilnase. Durch vorsichtiges Nachfeilen kann erreicht werden, dass die Falle dicht in das Schließblech greift.

http://www.obi.de/de/onlineServices/Heimwerker-Lexikon/index...

Schließblech – keeper plate, locking plate, striker plate


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Note added at 3 hrs (2006-12-22 14:07:12 GMT)
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Recessed strike plate?

If the latch does not catch, close the door slowly to watch how the latch bolt meets the strike plate. The bolt may be positioned above, below, or to one side of the strike plate. (Scars on the strike plate show where it is misaligned.) It is also possible the door has shrunk and the latch no longer reaches the strike plate. Once you have figured out the problem, try one of the methods shown here.
For less than a 1/8-inch misalignment of the latch bolt and strike plate, file the inside edges of the plate to enlarge the opening (right).

http://www.hometips.com/articles/door_locks_knob_fixes.html

A strike mechanism for a door lock comprising a recessed strike plate (9) which in use is fitted into a door jamb to receive a latch bolt (14) and a strike (10) which is pivotal between a first position in which the bolt (14) is held within the recess and the door is locked shut and a second position in which the bolt (14) is released so the door may be opened.

http://www.freepatentsonline.com/5219196.html

Lock: Bottom fitting deadlock with recessed strike plate.
http://www.dot.state.ia.us/procdist/lt00339web.pdf