ConstDerived, not authored: the sets are walked in gallery order, each highest band first (the way a set is pictured), and an icon is listed the first time its shape-and-tint pair appears, under the first set that draws it. Any set that draws the glyph is a valid address on the wire, so the first is as good as another. A test pins the count so a table edit is noticed.
Every distinct icon the built-in sets draw, in one list — Excel's fifty-two custom-icon choices, plus one: under the Excel Online palette the five-arrow set's side arrow is orange while the three-arrow set's is yellow.