main chain (backbone)

of a polymer
https://doi.org/10.1351/goldbook.M03694
That @L03546@ to which all other @L03619@ or @S05647@ or both, may be regarded as being pendant.
Note:
Where two or more chains could equally be considered to be the main chain, that one is selected which leads to the simplest representation of the molecule.
Source:
PAC, 1996, 68, 2287. (Glossary of basic terms in polymer science (IUPAC Recommendations 1996)) on page 2294 [Terms] [Paper]