(1) The purpose of the rules in subchapters 1 and 2 of this chapter is to provide a clear procedural framework under which the department administers the federal special supplemental food program for women, infants, and children, the so-called "WIC" program which is sponsored by the food and nutrition service (FNS) of the United States department of agriculture (USDA) and which has been administered in Montana by the department of public health and human services since approximately 1974.