A true French rule, also called une carton de Provence is a very old and popular recipe for a very large, crumbly bread. It can vary from small sizes to very large dimensions, but usually it's on the larger side of normal bread dough. A typical boule consists of many distinct sorts of flour, leavening agents and various flours in addition to all kinds of baking enhancers. The ingredients can vary greatly, as can the way in which they are combined. However, they all have something in common, and that's the fact that they create a bread which tastes absolutely delicious!