Vintage compartment bag from France with months indication

A special black leather handbag with a kind of linen folder inside with mention of the French months. The folders are parts between which you can put something in between each month and thus put everything in order of the months. What could this black leather bag be used for? Perhaps once used by a market master, for example. The vintage black leather bag is from the 40s or 50s and still looks good! See also the additional photos for this. The vintage bag closes well and is in neat condition.