Editing Ternary form (section)

==Compound ternary or trio form==
{{anchor|Trio form}}
In a trio form each section is a dance [[Movement (music)|movement]] in binary form (two sub-sections which are each repeated) and a contrasting trio movement also in binary form with repeats. An example is the [[minuet]] and trio from [[Joseph Haydn|Haydn]]'s ''[[Surprise Symphony]]''. The minuet consists of one section (1A) which is repeated and a second section (1B) which is also repeated. The trio section follows the same format (2A repeated and 2B repeated). The complete minuet is then played again at the end of the trio represented as: {{Nowrap|[(1A–1A–1B–1B) '''(2A–2A–2B–2B)''' (1A–1A–1B–1B)]}}. By convention in the second rendition of the minuet, the sections are not repeated with the scheme {{Nowrap|[(1A–1A–1B–1B) '''(2A–2A–2B–2B)''' (1A–1B)]}}. The trio may also be referred to as a double or as I/II, such as in Bach's polonaise and double (or Polonaise I/II) from his [[Orchestral suites (Bach)#Suite No. 2 in B minor.2C BWV 1067|second orchestral suite]] and his [[Bourrée]] and double (or Bourrée I/II) from his second [[English Suites (Bach)|English Suite]] for harpsichord.

[[File:Compoundbinaryformdiagram.png|500px|thumb|Diagram of a minuet and trio]]

The scherzo and trio, which is identical in structure to other trio forms, developed in the late Classical and early Romantic periods. Examples include the scherzo and trio (second movement) from [[Ludwig van Beethoven|Beethoven]]'s [[Symphony No. 9 (Beethoven)|Symphony No. 9]] and the scherzo and trio in [[Franz Schubert|Schubert]]'s [[String Quintet (Schubert)|String Quintet]].<ref name="HD2nd trio (2)" /> Another name for the latter is "composite ternary form".{{citation needed|date=August 2011}}

Trio form movements (especially scherzos) written from the early romantic era sometimes include a short [[coda (music)|coda]] (a unique ending to complete the entire movement) and possibly a short introduction. The second movement of Beethoven's Symphony No. 9 is written in this style which can be diagrammed as {{Nowrap|[''(INTRO)'' (1A–1A–1B–1B) '''(2A–2A–2B–2B)''' (1A–1B) ''(CODA)'']}}

[[Quickstep (march music)|Quickstep]] military marches, in particular, many marches by [[John Philip Sousa]] follow this form, and the middle section is called the "trio".{{cn|date=June 2024}} 

[[Polka]]s are also often in compound-ternary form.{{cn|date=June 2024}}

===Quasi compound form===

Occasionally the A section or B section of a dance like movement is not divided into two repeating parts. For example, in the Minuet in Haydn's String Quartet op. 76 no. 6, the Minuet is in standard binary form (section A and B) while the trio is in free form and not in two repeated sections. Haydn labeled the B section "Alternative", a label used in some Baroque pieces (though most such pieces were in proper compound ternary form).<ref>{{cite book |title=Musical Composition: Craft and Art |last=Belkin |first=Alan |location=New Haven and London |publisher=[[Yale University Press]] |date=2018 |pages=82–83 |isbn=978-0-300-21899-2}}</ref>