⍒
⍒Y gives indices that sort major cells descending. Stable, with the same ordering as Grade up.
⍒Y
⍒30 10 20 ⍝ 1x 3x 2x ⍒2 1 2 1 ⍝ 1x 3x 2x 4x
C⍒Y uses character collation C.
C⍒Y
C
'cba'⍒'abc' ⍝ 1x 2x 3x