The editor’s dual representation of a document. The ancient InterLisp editors, which represented a file/document in terms of the set of operations used to create it, may be relevant here. Think of the studies of Mozart’s composition process. Supposedly this analysis proceeded by carefully peeling off layers of paper (in reverse chronological order) that had been overlaid as Mozart edited his manuscript. The startling conclusion: On more than one occasion, the composer’s final work was identical to his original conception!