Suttavibhanga (explanation of the rules)

The Suttavibhanga can be divided into the rules for bhikkhus (monks) and the rules for bhikkhunis (nuns). The rules are grouped according to the punishments entailed for breaking them:

pārājika (rules entailing expulsion), saṃghādisesa (rules entailing temporary exclusion from the Saṃgha), aniyata (indefinite rules), nissaggiya-pācittiya (rules entailing forfeiture and expiation), pācittiya (rules entailing expiation),

pāṭidesanīya (rules about offences which should be expiated), sekhiya (rules about training) and adhikaraṇasamatha (rules for settling disputes). There are no aniyata rules for bhikkhunis.

The descriptions which follow are based on the Pāli Vinaya; Vinayas of the various schools that have been translated into Chinese may exhibit differences.

There are four pārājika rules for bhikkhus and eight for bhikkhunis. The four for bhikkhus forbid sexual misconduct, stealing, killing and lying about spiritual attainment.

Committing any of these results in the permanent expulsion of the offender from the Saṃgha. Accusations can be made by others, in which case confession is not necessary. However if the accusation differs from the testimony of the accused, the case is adjudicated by the Saṃgha.

There are thirteen saṃghādisesa rules for bhikkhus and seventeen for bhikkhunis.

Offenders are excluded from the Saṃgha for six days, having to live in a room apart and forbidden to speak to other members.

Thus they are virtually ostracized by other bhikkhus and bhikkhunis.

The offender is readmitted if in a meeting, twenty or more members of the Saṃgha are satisfied with his penance. Accusations can be made from outside the Saṃgha.

The two aniyata rules, of undetermined gravity, relate to sexual offences, and are specific to bhikkhus.

The gravity of the offence is determined according to the testimony of a female lay follower whose word is trusted. The offense may be brought forward by confession or accusation.

There are thirty nissaggiya-pācittiya rules for both bhikkhus and bhikkhunis, and concern the possession of forbidden items.

A person who violates the rules confesses his or her wrongdoing before the Saṃgha (a minimum of four people), before a group of two or three people, or before an elder.

Accusations cannot be brought forward by others.

The offender is reinstated if the confession is accepted. The forbidden items are confiscated by the Saṃgha and in principle returned to the original owner.

In pernicious cases, such as habitual offenders, special procedures concerning accusation and adjudication apply. The same goes as well for the offences listed below.

It should be noted that here "confession" refers to the formal notification made that one has committed an offence. It was a legal procedure whereby a bhikkhu or bhikkhuni applied for the reinstatement of his or her rights, and very different from the "confession" or "repentance" of Mahāyāna Buddhism.

There are 92 pācittiya rules for bhikkhus and 166 for bhikkhunis.

They are not rules about items but about various offences to do with eating outside set times and suchlike. Similarly to the previous group, such offences can be confessed before the Saṃgha, before two or three people, or before an elder.

Once the confession has been accepted, the offender can resume full rights as a member of the Saṃgha.

There are four pāṭidesanīya rules for bhikkhus and eight for bhikhunis.

They concern offences like accepting food from an unrelated bhikkhuni, and they must be acknowledged before another monk. Forgiveness is given immediately.

Thus it is enough to report the offence, and no kind of permission is needed. There are 75 sekhiya rules for both bhikkhus and bhikkhunis.

They mainly concern manners and deportment. Violating them does not incur any loss of rights. They are not so much real offences as something that perpetrators should reflect upon.

Both bhikkhus and bhikkhunis had seven adhikaraṇasamatha rules.

They were established as a means to settle any disputes that might arise in the Saṃgha.

Such settlement is by majority decision.

When violations occur, they are judged to be "faults", which appear the same as how sekhiya offences are judged.

Source

http://www.sakya-muni.jp/english/0004/early-buddhist-scriptural-sources.html