Term: (chain) identity period of a polymer https://doi.org/10.1351/goldbook.I00954 Definition: The shortest distance along the chain axis for translational repetition of the chain structure. The chain identity period is usually denoted by c. Synonymous with (chain) repeating distance. Source: Purple Book, 1st ed., p. 77 (http://old.iupac.org/publications/books/author/metanomski.html) Citation: '(chain) identity period of a polymer' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.I00954 License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.