⍋ — Grade up⍋Y gives indices that sort major cells ascending. Stable; uses structural ordering, without tolerance.
⍋30 10 20 ⍝ 2x 3x 1x
v←30 10 20 ⋄ v[⍋v] ⍝ 10 20 30
⍋2 1 2 1 ⍝ 2x 4x 1x 3x
C⍋Y uses a character collation array C.
'cba'⍋'abc' ⍝ 3x 2x 1x
See ⍒.