Definition: Rather long number made up of several distinct parts but with a form of musical unity, since all the music appears as a series of variations based on one theme (whether one first clear occurrence of the musical theme can be heard or not). Two-part (or more) number within one entity.
Example: “Alexander’s Ragtime Band” (1) (There’s no Business); “Beautiful Girls” (Ziegfeld Follies); “South American Way” (beginning of Down Argentine Way) - “Slap that Bass” (Shall We Dance) - “Pettin’ In The Park” (Gold Diggers of 33). NB : “The Babbitt and the Bromide” (Ziegfeld Follies) is a “simple” number because there is only a small-scale variation between the verses. This number is to be seen as a borderline case.