Para-equestrian classification 4, 5, 6, 7, 12a/b, 13, 14, 21, 26a, 31a/b and 32 are allowed to have a whip which is held or used by a groom. Grade 1 drivers with Profiles 1, 2, 3, 4, 5, 6, 7, 9, 10a, 12a/b, 13, 14, 26a, 31a/b and 32 are allowed to have a brake operated by a groom. Grade 1 drivers with Profiles 1, 2, 3, 4, 5, 6, 7, 9, 10a, 12a/b, 13, 14, 26a, 31a/b and 32 are allowed to have a strap on feet or foot trough. Grade II is for riders who are higher functioning than Grade
7-limit tuning Young's "The Well-Tuned Piano", Ben Johnston's String Quartet No. 4, and Lou Harrison's "Incidental Music for Corneille's Cinna". The Great Highland Bagpipe is tuned to a ten-note seven-limit scale: 1:1, 9:8, 5:4, 4:3, 27:20, 3:2, 5:3, 7:4, 16:9, 9:5. In the 2nd century Ptolemy described the septimal intervals: 7/4, 8/7, 7/6, 12/7, 7/5, and 10/7. Those considering 7 to be consonant include Marin Mersenne, Giuseppe Tartini, Leonhard Euler, François-Joseph Fétis, J. A. Serre, Moritz Hauptmann, Alexander John Ellis, Wilfred Perrett, Max Friedrich Meyer. Those considering 7 to be dissonant include Gioseffo Zarlino, René Descartes, Jean-Philippe Rameau, Hermann von Helmholtz, A.