[16] Some of these sketches were written during the earliest stages of the composition. Many use the old numbering of all-interval chords, and one even uses an all-interval chord which is not RI-invariant. Several of the items in the DDM folder are collections of sketches that feature a particular interval class. For example, DDM, no. 8 features interval class 5, DDM, no. 19 features interval class 2, and DDM, no. 20 features interval class 4.