Biochronological correlations between different sections can be established only with a reference scale showing the chronological sequence of biological events (range chart). This scale has to be synthesized from all local biostratigraphic data available. This fundamental operation, which is tedious when performed manually, can be characterized by a series of logical statements and automated. The principal problems of biochronological correlation are discussed and a method that establishes reliable chronological scale from raw stratigraphic data is described in detail.