Typologies correspond to shape directories specific to a class or its variants (OX, OX1, OX3; TR, TR1a, TR2, TR3, etc.). They correspond to directories produced in a region (Africa, Flanders, Maghreb), even if the containers are spread beyond.
There is no a priori repertoire: it is a construction carried out by archaeologists from the redundancy of containers with the same shapes, and thus based on the wish of potters to produce the same containers in series. The directories classify the containers by general shapes (open or closed, then plate, bowl, cup, etc.), then by elements of detail, often at the rim.
The name of most types consists of a number preceded by a prefix. This prefix identifies the typology, either by its author (Dragendorff, Dressel) or by the site at the origin of the classification (Camulodunum, Niederbieber). The number may be hierarchical, from 1 to x, by combining numbers (Morel 2152) or numbers and letters (Npic J12a).