Pair of adjacent constitutionally equivalent stereogenic units that are of like configuration.
Note: Usage of the term meso diad for describing structures with a symmetrically constituted connecting group is no longer acceptable because of the potential for confusion with the similar term used in organic chemistry to describe small molecules.
Source:
PAC, 2020, 92, 1769. 'Definitions and notations relating to tactic polymers (IUPAC Recommendations 2020)' on page 1773 (https://doi.org/10.1515/pac-2019-0409)