Syntax:

          WHILE lexpr LOOP
             statement_block
             [ EXIT LOOP ]
          END LOOP

statement_block will be executed as long as lexpr evaluates to a 1, or until [EXIT LOOP] is encountered. This is similar to REPEAT above, the difference being the statement_block of REPEAT loop will always execute at least once, whereas that of a WHILE loop may never execute (because the test is done first).

Example:

          WHILE no_button LOOP
             xx = xx + 1
             IF (xx == 10) THEN
                EXIT LOOP
             END IF
          END LOOP