“…Set class 6-Z19 is particularly rich in P 0,2c relations which involve either one or two voices skipping over, as well as a P 0,1 relation that skips over. By contrast, 6-Z19's 'Z partner', 6-Z44, is capable of seven distinct relations by whole-tone voice-leading (two single, two whole-tone contrary and three whole-tone similar, all without skipping over), emphasising the fact that, despite Voice-leading operation Number of instances P 1,0 (0) P 0,1 (14) (0, 0, 0, 0, +2, −2) 14 (5 shared with P 2s,0 ; 2 shared with P 0,2s ) P 2s,0 (34) (0, +1, 0, −1, 0, 0) 16 (5 shared with P 0,1 ) (+1, −1, 0, +1, −1, 0) 7 (0, 0, +1, −1, +1, −1) 11 P 0,2s (25) (0, +2, 0, −2, 0, 0) 11 (2 shared with P 0,1 ) (0, −2, +2, 0, −2, +2) 2 (0, +2, −2, +2, Ex. 17 shows the opening six bars of this piano piece.…”