The AMAA, its terms and conditions and the Administrative Procedure Act, 5 U.S.C§ 551-706, define the process for defining marketing orders and agreements. Anyone, including the secretary, can propose a marketing order or agreement. Where a person other than the secretary is the originator of the proposal, that person must submit a written request to the secretary. The final step in defining a marketing order or agreement is approval by referendum. As a general rule, two-thirds of producers, either in number or volume, must approve the proposed order or agreement. After approval, the order or agreement is binding on all liquidators in the marketing area indicated in the order or agreement. Marketing agreements are divided into three categories: (1) fruit, vegetables and special crops, (2) milk and milk products and (3) miscellaneous products. . . .