ISO 25378:2011 defines general terms for geometrical specifications, characteristics and conditions. These definitions are based on concepts developed in ISO 17450-1 and ISO 22432 and they are given by using a mathematical description based on Annex B of ISO 17450-1:2011. ISO 25378:2011 is not intended for industrial use as such among designers, but is aimed to serve as the "road map" mapping out the requirements based on geometrical features, thus enabling future standardization for industry and software makers in a consistent manner. ISO 25378:2011 defines general types of geometrical characteristics and conditions which can be used in GPS. These descriptions are applicable to a workpiece, an assembly, a population of workpieces, and a population of assemblies. These definitions are based on concepts of operators and the duality principle contained in ISO 17450-1 and ISO/TS 17450-2 and on the description of types of geometrical features defined in ISO 22432. Conceptually, these specification operators can be used as specification operators or as verification operators (duality principle). ISO 25378:2011 is not intended to define GPS specifications, symbology or other types of expression.