David Lewin showed that the T/I (“T-eye”) group is dual to a dihedral group acting on these objects whose three generators form orbits of size 2, 6, 8, and 24. Secondary operations like the Slide and Nebendverwandt act on these objects and can be written as products of P, R, and L. Leonhard Euler (10[1])visualized transformations on these objects with a hexagonal lattice diagram known as the Tonnetz that is studied in Neo-Riemannian theory. A functional analysis of these objects developed during the common practice period. These objects’ “quality” may be indicated with superscript symbols like a triangle or slashed circle. Inversion changes the voicings (10[1])of these objects, whose “progressions” are studied in harmony. (10[1])For 10 points, name these sets of three or more simultaneous notes that come in “major” and “minor” forms. ■END■