How is ternary form used in the Viennese waltz sets of the later 19th century?

A B A
It could be like: A - introduction; B - the waltz itself (with a various number of themes); A - Coda (in which the introduction reappear).
Or: A - the main waltz (theme), B - the rest of the waltzes (themes); A - Reprise of the main waltz (theme).
You may discover also: "ab" (in a bigger A); c (maybe "de", possible f) in the middle of the waltz; Reprise of "ab" (A), not necessary in this order (it may be like "ba").
But certain is an ABA form.