AbstractNodal nomenclature is compared with classical organic nomenclature, and the procedure by which an organic compound is given a nodal name is described. Parent hydride–especially hydrocarbon–names are derived from the names of structure graphs and are modified to incorporate descriptions of heteroatoms, unsaturation, free valences, and ionic charges. It is also shown how the substitutive method, though not an integral part of the nodal system, may nevertheless be used as a way to simplify the structure graphs without impairing the logic of the nodal system. For this purpose, it is indicated how to use prefixes or suffixes generally formed according to IUPAC Rules. The rôle of substitution in organic nodal nomenclature is more restricted than in classical nomenclature because many classical substituents are treated as part of the parent hydrides. The concept of “characteristic group” is not used in nodal nomenclature for similar reasons, and the term “principal substituent” is preferred to “principal charact