Circle Backslash ⍉
Monadic Circle Backslash means Transpose
mat
1 2 3
4 5 6
⍉ mat
1 4
2 5
3 6
Dyadic Circle Backslash means Dyadic Transpose
2 1 ⍉ mat
1 4
2 5
3 6
1 1 ⍉ mat ⍝ leading diagonal
1 5
Monadic Circle Backslash means Transpose
mat
1 2 3
4 5 6
⍉ mat
1 4
2 5
3 6
Dyadic Circle Backslash means Dyadic Transpose
2 1 ⍉ mat
1 4
2 5
3 6
1 1 ⍉ mat ⍝ leading diagonal
1 5