LOOP                     End Definition of DO/LOOP Loop

 1. DO
    .
    . [statements]
    .
    .
    [EXIT DO]
    LOOP [{WHILE | UNTIL} expression]

2. DO [{WHILE | UNTIL} expression]
   .
   . [statements]
   .
   .
   [EXIT DO]
   LOOP

    Ends the definition of a DO/LOOP loop.

  expression    A numeric expression. Nonzero values are equivalent to
                TRUE, while zero values are equivalent to FALSE.

       WHILE    Causes execution of the loop as long as expression is
                TRUE.

       UNTIL    Causes execution of the loop as long as expression is
                FALSE.

     EXIT DO    An optional means to escape from the loop before its
                termination.

        LOOP    Terminates the loop construct.

   -----------------------------------------------------------------------

      Notes:    DO...LOOP is a general-purpose looping construct. The
                optional termination test may be supplied at either the
                beginning or the end. If no test is supplied, EXIT DO is
                the only way to break out of the loop.