This is an A-B-A form. The A-section is in the minor mode. It opens with a brief introduction, establishing the piano accompaniment’s undulating rhythm; the voice then enters. The A-section concludes with a long stopping point–the first interruption of the steady rhythm.

The B-section is in the contrasting Major mode. It introduces a new melody and accompanying rhythm. Just as the A-section, the B-section ends with a long stopping point.

The A-section then returns, beginning immediately at the entrance of the voice. The original vocal line is reprised with minor changes.

 This is an A-form: The rhythm and texture remain constant throughout the composition.

There are two plausible ways of reading the form of this jazz composition. The first is an A-B-A: The A-section is the song’s main material, presented by all three instruments as an ensemble. The B-section consists of improvisatory solos. Then the A-section returns in its entirety.

A-B-C-D-A is another possible reading of the form. This reading takes into account that there are three improvisations: first, the piano solo; second, the trumpet solo, accompanied by the piano; third, the drum solo, periodically punctuated by the other two instruments.

Throughout the solos, the rhythmic drive is steady. The link between solos are carefully blurred: The piano keeps playing when the trumpet enters; both trumpet and piano play repeatedly during the drum solo. As a result, a large A-B-A, in which the B-section is divided into three sub-sections, would be my preferred reading.