The WHILE command evaluates a Boolean expression in the current
    language. If the value is true, the command list in the DO clause
    is executed. The command then repeats the sequence, reevaluating
    the Boolean expression and executing the command list until the
    expression is evaluated as false.

    If the Boolean expression is false, the WHILE command terminates.

    Related commands:

       EXITLOOP
       FOR
       REPEAT