⍬
⍬ is an empty approximate numeric vector: 0⍴0.
0⍴0
⍴⍬ ⍝ ,0x ⍬,1 2 ⍝ 1 2
Other empty types retain their prototypes.
3↑0⍴0x ⍝ 0x 0x 0x 3↑'' ⍝ ' '