The following volume of the National Edition is published in the Series B which contains works published posthumously. The basis for this edition is taken from the original sources, i.e. autographs, copies and prints corrected by the composer or, if possible, other reliable sources. All the changes and supplementations - if they are necessary - are graphically distinguished from the text. In the ''Source Commentaries'' musicologists will find fundamental information about the sources together with an evaluation of the degree of their authenticity, a description of mutual connections (called ''filiation'') and a discussion of the more important divergences as well as the principles of editing the music text of particular works. In the music text, beside Chopin's fingering, we give, in different type, the fingering used in contemporary concert practice and the ''Performance Commentaries'' explain all these elements of music notation which may raise doubts today. They include: writing out the ornaments in full, pedalling indications, suggestions as to the realisation of ''harmonic legato'' and alternate fingering.