In Repeating group dialog you can create a Repeating unit, an SRU polymer or a Link node; or you can change the repeat pattern and the label of these substructural groups.
Repeat pattern values
(ht) - head-to-tail (not displayed on the canvas)
hh - head-to-head
eu - either/unknown
Label values
number (e.g. 3)
range (e.g. 5-8)
lowercase letters ( a - z except: c and f )