In his “Ballades” Chopin created a new, typically Romantic, genre of piano music. Works of this type were not known in earlier instrumental music. Volume I of the National Edition contains all four of Chopin's “Ballades,” 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 the indication result from textual divergences in authentic copies or from difficulties in reading the text in an unambiguous way.
Chopin National Edition Volume I
(ed. Jan Ekier)