linear constitutional repeating unit

https://doi.org/10.1351/goldbook.09622
Constitutional repeating unit connected to exactly two other constitutional repeating units.
Notes:
  1. A linear constitutional repeating unit may be connected to one or more end-groups.
  2. End-groups attached to non-terminal constitutional repeating units are sometimes termed side groups. The use of the term side group in this meaning is not acceptable.
See: hyperbranched molecule (figure)
Source:
PAC, 2019, 91, 523. 'Nomenclature and terminology for dendrimers with regular dendrons and for hyperbranched polymers (IUPAC Recommendations 2017)' on page 532 (https://doi.org/10.1515/pac-2016-1217)