The folders csv, kern, lisp, and MIDI each contain representations of forty-nine mazurkas by Frédéric Chopin (1810-1849). The file C-6-1-ed, for instance, is short for Chopin's Mazurka in F-sharp minor op.6 no.1, edited. The term edited refers to alterations that have been made to the original kern files for these pieces (the originals being created by Craig Stuart Sapp and hosted at http://kern.ccarh.org/). The alterations correct small errors, and make it easier to write a function for timewise reading of a kern file.