When correcting FE (→EE), Chopin added accents under bass notes in the middle of each of those bars. In EE, a vertical accent was used in bar 40, which is characteristic for that edition.
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category imprint: Differences between sources; Corrections & alterations
issues: EE revisions, Authentic corrections of FE, Authentic post-publication changes and variants
notation: Articulation, Accents, Hairpins