In the Samavāyāṅga, two Śruta-skandhas (parts) have been attributed to the Ācārāṅga,[1] which is also called Brahmacaryādhyayana. In the Samavāyāṅga, its chapters are called 'Nava Brahmacarya'.[2] The Ācārāṅga Niryukti mentions it as consisting of nine Brahmacaryādhyayanas [3]. The second part of the ' Ācārāṅga ' is Āyāracūlā. This proves that the description of Dvādasāṅgi as found in the Samavāyāṅga is a composition which dates back to Āyāracūlā. The Ācārāṅga did not have any division prior to this. This happened only after Āyāracūlā was composed by Bhadrabāhu.
The Niryuktikāra has given 10 synonyms of the Ācārāṅga.[4] They are Āyāra, Ācāra, Āgāla, Āsāsa, Āyarisa, Aṅga, Āinna, Ājāi and Āmokkha.