⍒ Grade Down r←⍒y

If y is an array, r is the indices that would sort the major cells of y in descending order according to total array ordering. Grading is stable, that is, the indices of two cells that are equal appear in r in the same order as the cells themselves. Supports the origin extra argument, which offsets the result by the origin; supports the tolerance extra argument for the comparisons.

If y is a dictionary, r is the keys that would sort the values in descending order.

Supports the tolerance extra argument for the comparisons; supports the backward extra argument, which returns the ⍋ Grade Up of y.