Nielsent's innovative approach to musical form and structure prompts many questions about design and compositional method. Surviving source materials suggest that he did not generally work with extensive precompositional sketches but preferred to work with extended continuity drafts, often of an almost improvisatory character, from which the eventual shape of the final work would gradually begin to emerge. Indeed, as Michael Fjeldsøe and others have observed, Nielsen often remained unclear about the way in which a work might end until he was well advanced with the drafting process. This working method has created numerous challenges for the editors of the Carl Nielsen Complete Works, since it is sometimes difficult to establish an absolute Fassung der letzten Hand for Nielsen's scores – Nielsen was frequently open to suggestions for changes from colleagues, friends, and family, and he sometimes adopted a pragmatic attitude to consistencies of notation and even, at times, instrumentation (which is not to say that he was similarly relaxed about practical standards of musical realisation or interpretation – quite the contrary, as his correspondence reveals). And for musicologists, especially analysts, it is almost impossible to trace how Nielsen's large-scale structures were planned or emerged, prior to a relatively complete draft stage.