The Well-Tempered Clavier I by J. S. Bach, in the 1997 revision, includes some minor changes in the areas of embellishments and accidentals, as well as a notable correction in the notation of the Prelude in B major, which has not been included in any previous editions. The edition from the Wiener Urtext Edition does not follow the evidently erroneous autograph from measure 11, which has been shown not to have been revised by Bach, but rather the musically more logical version from the early draft and a correction by J. Fr. Agricola, which originates from his time as a student of Bach. Difficulty level: 2-3.