In **rounded binary form**, the opening material returns near the middle of the second reprise: $ \overset{\text{A}}{\text{||: a :||}}\kern-1.258ex\overset{\text{B}}{\text{||: b a}^{\prime}\text{ :||}} $ The classification of this form is a matter of some debate. Some theorists argue that the return of a′ makes the form ternary, typically maintaining that, apart from the notation, the aural perception of the form is ternary. Others argue that the form remains divided into two larger formal units and is therefore structurally binary, with a smaller “ternary” form nested within it; this is one reason some theorists refer to the rounded binary as the [[small ternary]]. Over time, composers increasingly omitted repeat signs, making the underlying binary organization less perceptible. Nevertheless, historical traces of that organization remain, even where it is apparent neither in the notation nor to the ear. For practical purposes, the terms *rounded binary* and *small ternary* may be used interchangeably.