kinnispunkt, lähtejoon ja/või -pind, mis on lähteks mõõtmestamisel, ISO GPS süsteemi poolt identifitseeritud geomeetrilist omadust iseloomustava suuruse tüübi mõõde kategooria, category of type size of geometrical property are identified in the ISO GPS system, some important part of an object—such as a point, line, plane, hole, set of holes, or pair of surfaces—that serves as a reference in defining the geometry of the object and (often) in measuring aspects of the actual geometry to assess how closely they match with the nominal value, which may be an ideal, standard, average, or desired value