Classes of Narrators(طبقات الرواة)
This term is applied to narrators of similar status such as nearness in age, even approximately and in terms of meeting with elder narrators.
Tabaqat , pl. of tabaqa, "everything which is related to another and which is similar or analogous to it, which comes to mean a layer of things of the same sort (Flügel, Classen, 269, n. 1).From this a transition can be made to the idea of a "rank, attributed to a group of characters who have played a role in history in one capacity or another, classed according to criteria determined by the religious, cultural, scientific or artistic order etc." (Hafsi, i. 229; cf. al-Tahanawi, Kashshaf, 917).
In biographical literature it is the "book of classes" of characters arranged by "categories" and organised into "generations".