The classification of āgamas into aṅga, upāṅga, mūla and cheda is not very ancient. Before the 13th-14th century of vikrama, this kind of classification was not available. There is no uniformity regarding the numbers and the names of Mūla Sūtras within the different branches of Śvetambara tradition. As far as Uttāradhyayana and Daśavaikālika are concerned, all the branches of Śvetambara tradition unanimously accept them as the Mūla sūtra. Sthānakavāsi and Terāpanthī do not include Āvaśyaka Niryukti and Piṇḍa Niryukti in the list of Mūlasūtras. They accept Nandī and Anuyogadvāra as Mūla sūtra. Some ācāryas of Idol worshipping branch (Mūrtipūjaka) of Śvetambara tradition, accepts Ogha Niryukti as Mūla sūtra like Piṇḍa Niryukti.
There is no clear conviction available as to why these texts are called as Mūla sūtra. According to Acharya Mahāprajña, when the concept Śrutapuruṣa (the metaphorical canonical man) was taking shape in the period of Cūrṇī, Ācārāṅga and Sūtrakṛtāṅga are set as two Mūla sthānīya or Caraṇa Sthānīya (as two legs of Śrutapuruṣa) but when the tradition of forty five āgamas was established, a change in the concept of Śrutapuruṣa also occurred. Now, Daśavaikālika and Uttarādhyayana are accepted as the caraṇasthānīya of Śrutapuruṣa.[1]
The concepts mentioned above manifest that Mūla means caraṇa (legs) hence Uttarādhyayana and Daśavaikālika Sūtra can be called as Caraṇasthānīya accepting them as Mūla. As a minimum four Mūla sūtras have been accepted by all the Jain sects but some have included more too. The reason for the inclusion of those texts in Mūla sūtra is still a matter of research.
All the Śvetambara sects are unanimous in the acceptance of the numbers of aṅga and upāṅga but they differ in the numbers of mūla, cheda etc. According to Śvetambara pratimā pūjaka i.e. idol worshippers, Mūla sūtras are as follows -
- Uttarādhyayana
- Daśavaikālika
- Āvaśyaka
- Piṇḍa Niryukti
Some others have accepted Ogha Niryukti also as Mūla text. In the view of Sthānakvāsi and Terāpanthī, Mūla Sūtras are as follows -
- Uttarādhyayana
- Daśavaikālika
- Anuyogadvāra
- Nandī
Śvetambara idol-worshipping tradition count Anuyoga and Nandī as Mūla Sūtra. This clears the fact that the entire Śvetambara tradition, accepts anuyoga and Nandī in the series of āgamic texts, though they are classed differently.