Archaeologists create terminology about periods in order to classify finds by a schema of relative chronology (periods) and to relate sequences of settlements and cultures. The use of a certain terminology implies a number of ideas that may differ from researcher to researcher, so that there is a tendency to define cultural periods of even the same culture differently and to use different terminology for them (e.g questions about the definition or even existence of the Early Minoan III period caused disagreements between archaeologists in the past –see Zons 1967, Warren 1984). Period names may represent the same or different concepts depending on the view or social group. Traditional names may be preserved, altered or redefined (Barber 1987) on the base of earlier literature. Even if an established terminology about periods exists, it sometimes operates against explanation and understanding. (see comments on tripartite system of Evans, made by Dickinson in Dickinson 1994) The nomenclature principles lead to ambiguity since a name may designate several concepts. The problem is similarly known from biological species definitions, and seems to be common to taxonomies that follow the evolution of science.