Patek Philippe CH 28-520 C

Generations run left to right, ancestors first, and the axis along the top is ordinal rather than linear: each band is one generation, labelled with the range of sourced introduction years it contains. A band reads “—” when no caliber in it has a year anyone published — the gap is the finding, not a rendering failure. Dotted arcs above and below the drawing are related edges — successor, drop-in, no-derivation — which are stored in a different table from lineage and can never form part of an ancestry path.