 The first concept consisted of five closely spaced blocks fronted by an anti-tank ditch.The entry for the "ouvrage" was to be built in a ravine to the rear, with a 60 cm rail line running to a supply network farther behind the lines.The plan was rejected in July 1929 by CORF (Commission d'Organisation des Régions Fortifiées), the central planning agency for the Maginot Line.