Most tianguis operate more according to tradition than by formal rules. All have some kind of administrator or administration committee. The job of administrators is to interact with local authorities on behalf of tianguis sellers and manage internal affairs, especially the assignment of spaces and the collection of rental fees. The first rule is the process of negotiating for a space, but often this includes the denial of spaces for those who are unknown to the administration. Another is for vendors to watch out for authorities and warn others of authorities who may come to inspect sellers. In some markets, bartering is making a comeback, especially in the rural areas, such as the northeast of Morelos state. In one market in Zaculapan, 150 of 400 vendors state that they accept bartered goods, especially in produce and staple food products such as milk and bread. One reason for this is that many rural families lack cash, but raise produce for sale on their own farms and orchards. This tradition has existed for centuries, but increases in hard times.