⊂ — Enclose / Partitioned enclose⊂Y makes a rank-zero array containing Y.
⍴⊂1 2 3 ⍝ 0⍴0x
↑⊂1 2 3 ⍝ 1 2 3
(⊂3)≡3 ⍝ 0x
⊂[K]Y encloses cells on axes K.
⊂[2]2 3⍴⍳6 ⍝ (1 2 3⋄ 4 5 6)
N⊂Y starts partitions at positive marks along the last axis. Leading zero marks are ignored.
1 0 1 0⊂'abcd' ⍝ 'ab' 'cd'
A mark greater than 1 starts extra empty partitions. Scalar marks extend; [K] selects the partition axis. See also ⊆.