By Kurtis Schaeffer (University of Virginia, 2009)
Exoteric Scripture (མདོ་, mdo, sūtra) is the first of the Kangyur’s two main divisions (the second of which is Esoteric Scripture, or tantras). Situ’s catalog presents the first 94 titles in this category as being organized according to the order in which they were taught by the Buddha. Here, he uses a popular system in which the Buddha’s teachings are ordered into a sequence of the turning of “Three Wheels,” with (1) the first “wheel” referring to the scriptures on monastic conduct, (2) the second “wheel” referring to the Perfection of Wisdom literature, and (3) the third “wheel” being the sūtras.
Following the three turnings, the remaining 267 exoteric scriptures are placed in a fourth “collected sūtras” category, which is where the majority of the Hīnayāna and Mahāyāna sūtras are actually found.