Hantzsch-Widman heteroatom-replacement framework: standard prefix table (oxa/thia/aza) for monocyclic heterocycles

The Hantzsch-Widman 1887 heteroatom-replacement nomenclature: for monocyclic rings a standard table assigns prefixes to the most common heteroatoms in a fixed priority order (F, Cl, Br, I, O, S, Se, Te, N, P, As, …), with the ring name…