Chopin composed his ''Mazurkas'' continuously from 1825 to 1849. The half-utilitarian genre was a point of departure, gradually becoming a form of meditative lyricism - the most personal statement of expression. Chopin's ''Mazurkas'' present a number of specific performance problems resulting from such causes as the diversity of individual mazurkas, their collection in opus groups byChopin and his drawing inspiration from dance forms of Polish folk music. Volume No. 4 contains 43 mazurkas. Of the variants in musical notation, those designated ''ossia'' were marked in this way by Chopin himself or inscribed in his hand in pupils' copies, while those without this indication result from textual divergences in authentic copies or from difficulties in reading the text in an unambiguous way. The miniature version of the National Edition does not contain source commentary or performance notes.