4 great standards
Although the Vibhanga and Khandhakas cover an enormous number of cases, they do not cover every possible contingency in the world; and from what we have seen of the way in which the Buddha formulated the rules, dealing with cases as they arose, there is reason to doubt that he himself wanted them to form an airtight system. As for cases that did not arise during his lifetime, he established the following four guidelines for judgment, called the Great Standards (a separate set from those he formulated at Bhoganagara) for judging cases not mentioned in the rules:
1. "Bhikkhus, whatever I have not objected to, saying, 'This is not allowable,' if it fits in with what is not allowable, if it goes against what is allowable, that is not allowable for you.
2. "Whatever I have not objected to, saying, 'This is not allowable,' if it fits in with what is allowable, if it goes against what is not allowable, that is allowable for you.
3. "And whatever I have not permitted, saying, 'This is allowable,' if it fits in with what is not allowable, if it goes against what is allowable, that is not allowable for you.
4. "And whatever I have not permitted, saying, 'This is allowable,' if it fits in with what is allowable, if it goes against what is not allowable, that is allowable for you."
(from Vinaya Pitaka , Mv.VI. 40)
