The next step is to define the beginning of Part One, and end of Part Two, by separating the introduction and coda (if present) from the body of the form.
Beethoven, pianoforte sonatas: op.

57, Andante, Theme.
Op.

109, _Andante_, Theme.
Op.

111, last movement, Theme of Variations.
Op.

79, _Andante_, first 8 measures (unusually small); same sonata, last movement, first 16 measures.
Op.