erythro structures

in a polymer
Also contains definition of: threo structures in a polymer
https://doi.org/10.1351/goldbook.E02211
The
relative configuration
at two contiguous carbon atoms in the main chain bearing, respectively, substituents a and b (a ≠ b), is designated by the prefix erythro or
threo
, as appropriate, by analogy with the terminology for carbohydrate systems in which the substituents are OH. Examples:
Similar systems in which a higher level of substitution exists may be treated analogously if the erythro or
threo
designation is employed to denote the relative placements of those two substituents, one for each
backbone
carbon atom, which rank highest according to the
Sequence
Rule.
Source:
Purple Book, 1st ed., p. 36 [Terms] [Book]