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b. 18

composition: Op. 28 No. 8, Prelude in F♯ minor

..

The engraver of EE1 overlooked  restoring d2 on the 4th demisemiquaver on the 2nd beat. The accidental was added in EE2.

category imprint: Interpretations within context; Differences between sources

issues: EE revisions , Errors in EE

b. 19

composition: Op. 28 No. 8, Prelude in F♯ minor

..

None of the sources includes a  restoring b1 in the 3rd to last demisemiquaver. A comparison with two previous appearances of that bar – b. 1 and 5 (b. 2 is marked in an abridged manner as a repetition of b. 1) – proves that it was Chopin's mistake in A, not noticed in any of the remaining sources.

category imprint: Interpretations within context; Editorial revisions

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

b. 21

composition: Op. 28 No. 8, Prelude in F♯ minor

..

In the sources, there are no accidentals before the first and last notes of the 3rd L.H. figure. Therefore, the bottom one should be interpreted as a due to the  in the previous figure (it is particularly clear in the notation of the sources, in which the 3rd figure is still written in the bass clef). Naturally, it is Chopin's oversight – the harmonic context requires the notes to be interpreted as a1 and a; in such a situation, the top one does not need a , and Chopin considered an accidental next to the bottom one superfluous in such cases (cf. b. 3-4). In the main text we add a cautionary  also next to a1

category imprint: Interpretations within context; Editorial revisions

issues: Omissions to cancel alteration , Inaccuracies in A , Errors repeated in GE , Errors repeated in FE , Errors repeated in EE

b. 21

composition: Op. 28 No. 8, Prelude in F♯ minor

..

The fourth demisemiquaver of the 3rd group and the 3rd note of the 4th group should be interpreted in A (→FCGE) as g2, since there are no accidentals next to them, and the note at this pitch in the 2nd group is provided with a . Both the harmonic context and the rule of the figurations' structure applied in a vast majority of the cases (cf. b. 4 and 13) are strong arguments in favour of the assumption that Chopin overlooked the  restoring g2. The accidental was added in FE (→EE). 

category imprint: Interpretations within context; Differences between sources

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

b. 22

composition: Op. 28 No. 8, Prelude in F♯ minor

..

The  (cautionary?) present in all sources before d1 in the 3rd L.H. figure is almost certainly a remaining part of the initial notation of the quavers in the 1st half of the bar, which were written down as d1. After the notation had been changed, the  was no more necessary, hence we omit it in the main text. In the same 3rd L.H. figure, one can see in A a crossed-out  before c2. The accidental is not necessary, yet, due to c3 in the R.H., we give it in the main text. It was most probably for the same reason that it was also added in FE2 (→EE), also in the 4th figure. EE repeated in the 4th figure also the  before d1.

category imprint: Editorial revisions; Corrections & alterations; Source & stylistic information

issues: EE revisions , Corrections in A , Cautionary accidentals , Deletions in A , Enharmonic corrections , FE revisions