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b. 16

composition: Op. 45, Prelude in C♯ minor

..

FE1 is lacking a  before the 2nd quaver of the 2nd part of the bar. That patent inaccuracy was corrected in FE2 and EE. GE also has the correct version.

category imprint: Source & stylistic information

issues: Accidentals in different octaves , Inaccuracies in FE

b. 17

composition: Op. 45, Prelude in C♯ minor

No indication in FE (→EE)

ten. in GE

..

The indication ten. was probably added by Chopin in [A2] (→GE) to make the notation more precise. 

category imprint: Differences between sources

b. 18

composition: Op. 45, Prelude in C♯ minor

No accidental in FE (→EE1)

G based on the notation of FE 

in GE & EE2

Our variant suggestion

..

It is difficult to decide whether we are dealing here with one authentic version or with two authentic ones. FE1 has no accidentals in this bar, and such sloppy notation (naturals are obviously needed to lower d to d) suggests that also the  lowering G to G could have been omitted. On the other hand, it i s precisely this observation that could have inspired the reviser of GE to add a  in that place, so both  and G could possibly be the only authentic version. For that reason we decide to have a variant solution. 

In versions with the natural we add a cautionary  before g in the following bar.

category imprint: Interpretations within context; Differences between sources; Editorial revisions

issues: Omission of current key accidentals

b. 18-19

composition: Op. 45, Prelude in C♯ minor

No tie to in FE (→EE1)

tied in GE & EE2

Our variant suggestion

..

The sustaining of a as shown in GE is probably authentic, as there is no special reason for a revision here. On the other hand, the version of FE (→EE) is probably authentic as well, so in our main text we leave the choice to the performer.  

category imprint: Differences between sources

b. 18

composition: Op. 45, Prelude in C♯ minor

No accidentals (d) in FE1

 d in FE2

lowering D to D and d1 to d1 in FEJ

Three  D in GE & EE

..

FE1 does not have a single accidental in this entire bar, which means that the diminished chord d-f-a is the harmonic basis. This is how it was understood in FE2, adding a cautionary  before the 1st quaver of the L.H. Chopin's corrections in FEJ and the error-free version of GE show that Chopin's intention here was to have a D major chord as the harmonic basis. The reviser of EE added the relevant naturals here too. Cf. a further note for this bar. 

category imprint: Differences between sources

issues: Annotations in teaching copies , EE revisions , Errors in FE , Annotations in FEJ , FE revisions