2-2.5 Specifications Specifications are generally used when purchasing an end item rather than a service. Specifications must state the identified needs completely, considering the nature of the commodities being purchased. Whenever standard or modified commercial products will meet these requirements, product descriptions should be used instead of specifications. Specifications may be stated in terms of: Function — so a variety of commodities may be considered. Performance — including the range of acceptable characteristics or the minimum acceptable standards. Design requirements — provide exact dimensions, materials, or characteristics.