The Mahāpadesa Sutta describes about the "Four Great Authorities (Mahāpadesas)" that a disciple should refer, if any one claims some new thing to be the word of the Budhha.
The Buddha tells the monks of the four mahāpadesā to be respected by them. If a monks says he has a certain teaching direct from the Buddha himself, his statement should be compared with the rest of the Vinaya and Dhamma; if these do not agree, it should be rejected; if they do, accepted.
The same applies to that which is said to have been learnt from a group of monks led by a Thera from a body of senior monks residing in a certain place, or from a single senior monk, proficient in the Dhamma, the Vinaya, and the Mātikā. A.ii.167ff.; the sutta is incorporated in the Mahāparinibbāna Sutta (D.ii.123ff).
Apart from the above four great authorities, Theravadins use another four Authorities called "The Four Vinayas". What are they?