The notion of an ETOL system with rank is defined. It extends naturally studied already notions of an DOL system with rank and of an ETOL system of finite index. It turns out that in this way one gets an infinite hierarchy of classes of languages (each one being a full AFL) within the classes of ETOL languages. This hierarchy starts with the class of ETOL languages of finite index and it fills in the class of nonexpansive ETOL languages. Some other properties of the class of ETOL systems with rank are also studied.
Ehrenfeucht, Andrzej and Rozenberg, Grzegorz, "On ETOL Systems with Rank ; CU-CS-117-77" (1977). Computer Science Technical Reports. 115.