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b. 6

composition: Op. 28 No. 13, Prelude in F♯ major

..

The  restoring g in the 2nd half of the bar is absent in all the sources. It is one of Chopin's most common mistakes. The g note is so obvious that EE did not notice the mistake in spite of the cautionary  having been added before g1 in the 2nd R.H. chord.

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , Omissions to cancel alteration , Errors of A , Errors repeated in FE , Errors repeated in EE

b. 8

composition: Op. 28 No. 13, Prelude in F♯ major

..

In the main text we add cautionary accidentals before f and b.

category imprint: Editorial revisions

b. 16

composition: Op. 28 No. 13, Prelude in F♯ major

..

The inaccurately written (too low) 1st quaver in the 2nd half of the bar looks like F in A, and it was reproduced as such in FC (→GE1). The fact that Chopin must have meant G is evidenced both by the harmonic context (confirmed by analogous b. 32) and the common Chopinesque manner of writing notes under the 1st line clearly lower and so that they do not touch the line. The mistake of GE1 was corrected in GE2 (→GE3). 

category imprint: Graphic ambiguousness; Differences between sources

issues: GE revisions , Inaccurate note pitch in A , Errors repeated in GE

b. 17

composition: Op. 28 No. 13, Prelude in F♯ major

..

We add a cautionary  before e1 in the main text.

category imprint: Editorial revisions

b. 18-20

composition: Op. 28 No. 13, Prelude in F♯ major

..

The crossing-out visible in A before the 8th quaver in b. 18 covers probably a  (cautionary?) intended for e. Chopin realized that the accidental was not necessary here, yet in the next bars he would still write and cross out sharps before e notes, e.g. before E at the end of b. 20.

category imprint: Source & stylistic information

issues: Deletions in A , Last key signature sign