The Vinaya Pitaka, the first division of the Tipitaka, is the textual framework upon which the monastic community (Sangha) is built. It includes not only the rules governing the life of every Theravada bhikkhu (monk) and bhikkhuni (nun), but also a host of procedures and conventions of etiquette that support harmonious relations, both among the monastics themselves, and between the monastics and their lay supporters, upon whom they depend for all their material needs.
I. Suttavibhanga — the basic rules of conduct (Patimokkha) for bhikkhus and bhikkhunis, along with the "origin story" for each one. The Suttavibhanga contains the basic training rules for bhikkhus and bhikkhunis, along with the "origin story" for each one. These rules are summarized in the Patimokkha, and amount to 227 rules for the bhikkhus, 311 for the bhikkhunis.
A. Mahavagga — in addition to rules of conduct and etiquette for the Sangha, this section contains several important sutta-like texts, including an account of the period immediately following the Buddha's Awakening, his first sermons to the group of five monks, and stories of how some of his great disciples joined the Sangha and themselves attained Awakening.
B. Cullavagga — an elaboration of the bhikkhus' etiquette and duties, as well as the rules and procedures for addressing offences that may be committed within the Sangha.