A five-part rondo contains three refrains separated by two episodes: ABACA. (We will occasionally use these short-hand letter designations (A, B, and so on) to label rondos, but get in the habit of labeling the sections as “Refrain 1,” “Refrain 2,” “Episode 1,” etc., to avoid ambiguity with lower-level, embedded forms.)
The episodes of a five-part rondo are interior themes or second-theme complexes. It is more common to find a second-theme complex in Episode 1 than it is to find one in Episode 2. Often, the returns of the refrain are ornamented or abridged.
The older rondeau, from which this formal type derives, could feature many more refrains and episodes. Occasionally, therefore, you will find a seven-, or even nine-part rondo in the classical style.