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b. 15

composition: Op. 25 No 1, Etude in A♭ major

..

In A, CDP, and FE, there is no  raising d1 to d1. This patent oversight was corrected in GE and EE. AI also includes the correct text.

category imprint: Interpretations within context; Differences between sources

issues: Accidentals in different octaves , Inaccuracies in FE , GE revisions , Omission of current key accidentals

b. 16

composition: Op. 25 No 1, Etude in A♭ major

..

In A, CDP, FE, and EE1, there is no  raising d2 to d2. This patent oversight was corrected in GE and EE2 (→EE3). AI also includes the correct notation.

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , Errors in FE , Errors in EE , GE revisions , Omission of current key accidentals , Errors of A

b. 17

composition: Op. 25 No 1, Etude in A♭ major

d1 in AI, A (→CDP,GE) & EE

c1 in FE

..

In the main text we give the version with d1, present in the majority of the sources, including in A. The version of FE could be a result of Chopin's proofreading, however, one cannot exclude a mistake of the engraver or copyist.

category imprint: Differences between sources; Editorial revisions; Corrections & alterations

issues: Authentic corrections of FE

b. 17

composition: Op. 25 No 1, Etude in A♭ major

..

In the main text we add cautionary  before d2.

category imprint: Editorial revisions

b. 18

composition: Op. 25 No 1, Etude in A♭ major

F minor in AI

C major & F minor in A (→CDP,GE), FE & EE

..

The version of AI, closely analogous to bar 20, is undoubtedly original. In A one can see traces of rearranging this version to the final text.

category imprint: Differences between sources; Corrections & alterations

issues: Deletions in A