The value of ⎕DIV determines how division by zero is to be treated.  If ⎕DIV=0, division by 0 produces a DOMAIN ERROR except that the special case of 0÷0 returns 1.

If ⎕DIV=1, division by 0 returns 0.

⎕DIV may be assigned the value 0 or 1.  The value in a clear workspace is 0.

⎕DIV is an implicit argument of the monadic function Reciprocal (÷) and the dyadic function Divide (÷). ⎕DIV has Namespace scope.

      ⎕DIV←0
 
      1 0 2 ÷ 2 0 1
0.5 1 2
 
      ÷0 1
DOMAIN ERROR
      ÷0 1
      ^
 
      ⎕DIV←1
 
      ÷0 2
0 0.5
 
      1 0 2 ÷ 0 0 4
0 0 0.5