The archeological notion of cultural periods is based on cultural semantics. Chronological systems based on such periods are notoriously controversial, due to the complexity of the relationships between contextual phenomena and spatiotemporal values. Nevertheless, they play a key-role in archeological discussion. Several projects have attempted to define standard systems of periods for indexing databases, interpreting the spatiotemporal or stylistic inclusion as a “broader/narrower term” relationship based on ISO2788 (e.g. The J.Paul Getty Trust College Art Association 2000, AAT 2000). This approach is not expressive enough to capture the actual complexity, resulting in differences between chronological systems being able to be justified by the differences in the initial definition and subsequent (re)interpretation of observations