These bars, making up the second line of A, contain a few distinct examples of Chopin's manner of writing notes on ledger lines. With the visibility of such a note probably in mind the composer shaped the note-head as a short vertical stroke which sometimes was extended enough to look like an additional downward crotchet stem. In the discussed bars it pertains to R.H. c1 in bars 4-6, as well as c1 and a in bar 7. Telling are in particular the notes in bars 5 and 7, where the descending direction of arpeggios makes any sustentions impossible.
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category imprint: Source & stylistic information
issues: Uncertain notes on ledger lines
notation: Rhythm