Entries in the Chemical Substance index also include text modification phrases, which describe aspects of the substance that were studied. Index names are built around a parent , generally the name of a structural skeleton plus a suffix denoting the principal group. The index name is invented so that the parent appears first in the name printed in the index. This practice allows substances with the same structural skeleton to appear near each other in the alphabetically arranged index. Substituents on the parent structure are listed next in the name.
Stereochemical information appears at the end of the name.
The molecular formula index provides CA index names, CAS Registry Numbers, and abstract numbers for chemical substances identified by molecular formula. Element symbols in the molecular formula used in the Formula Index are arranged according to the Hill system. Formulas for substances that do not contain carbon are arranged alphabetically by element symbol. Elemental components are arranged in Hill order. Entries give CAS registry number, Ring File number, index name, molecular formula, WLN, and structure diagram.