Migration level must be such that ⎕ML<1 (otherwise ∊ means Enlist. See Enlist).
Y may be any array. R is an array with the same shape and structure as Y in which a numeric value is replaced by 0 and a character value is replaced by ' '.
∊(2 3⍴⍳6)(1 4⍴'TEXT') 0 0 0 0 0 0 ' '=∊'X' 1