Rules of order consist of rules written by the body itself, but also usually supplemented by a published parliamentary authority adopted by the body. Typically, national, state, and other full-scale legislative assemblies have extensive internally written rules of order, whereas non-legislative bodies write and adopt a limited set of specific rules as the need arises.
In the United States, the parliamentary authority adopted by most state legislatures is Mason's Manual of Legislative Procedure, and the one adopted by most other deliberative assemblies is Robert's Rules of Order.
U.S organizations dedicated to promoting the general use of parliamentary procedure include National Association of Parliamentarians and American Institute of Parliamentarians.