configurational repeating unit

in polymers
The smallest set of successive configurational base units that prescribes configurational repetition at one or more sites of stereoisomerism in the main chain of a regular macromolecule, a regular oligomer molecule, a regular block or a regular chain.
PAC, 1996, 68, 2287. 'Glossary of basic terms in polymer science (IUPAC Recommendations 1996)' on page 2291 (