⍉ — Transpose⍉Y reverses axis order.
⍉2 3⍴⍳6 ⍝ 3 2⍴1 4 2 5 3 6
In A⍉Y, each item of A names the result axis for the corresponding source axis. Labels start at 1 with no gaps.
2 1⍉2 3⍴⍳6 ⍝ 3 2⍴1 4 2 5 3 6
Repeated labels select diagonals, taking the smallest participating dimension.
1 1⍉3 3⍴⍳9 ⍝ 1 5 9