"duties of their order"

The term sangha is used to describe a community of Buddhist monks. Ten principal precepts and seventy-five minor rules for novices rules define how the members of the Sangha should conduct themselves in matters such as proper social etiquette, accepting and consuming food, handling their robes, the delivering of sermons and other miscellaneous day-to-day activities and social interactions.

A fully-fledged monk has to comply with 227 rules contained in a book called Patimokkha.

Read the Bhikkhu Patimokkha - The Bhikkhus' Code of Discipline translated from the Pali by Thanissaro Bhikkhu.  

View a photographic documentary on the Sangha's duties

The Bhikkhus' Rules - A Guide for Laypeople - compiled and explained by Bhikkhu Ariyesako also makes for interesting reading.