In the S-group dialog, you can create a repeating unit, an SRU polymer, a link node, or a copolymer.
It is also possible to change the repeat pattern and the label of these substructural groups.
Repeat Pattern Values
(ht): Head-to-tail (not displayed on the canvas).
Number (for example, 3).
Range (for example, 5-8).
Lowercase letters (a-z except for c and f).
Co for copolymers.