PL/0: Meaning (information, definition, explanation, facts)

PL/0 is a simplified version of the general purpose programming language PL/I, intended as an educational programming language.

The following example is taken from [1].

VAR x, squ;

PROCEDURE square;
BEGIN
   squ := x * x
END;

BEGIN
   x := 1;
   WHILE x <= 10 DO
   BEGIN
      CALL square;
      !squ
   END
END.

This program outputs the squares from 1 to 10.