These are the scarcest proofs printed by France. Discontinued in the early 1960's they were made by the government stamp printery from the unhardened Die to detect minute defects that could cause problems during the printing process. Produced only in one color (sepia) usually only

three to five were printed; one ultimately going to the official Archives, one to the Postal Museum, and the rest left to the philatelic world. If a defect were found, the Die was retouched and another set of proofs prepared. This process was repeated until the die was faultless and ready to be hardened.