The UNTIL statement marks the beginning of an UNTIL  loop  or  qualifies
  the execution of another statement.

  Examples

  UNTIL Z% = 100%
       .
       .
       .
  NEXT

  100    A% = A% + 1% UNTIL A% = 200%

1  –  Syntax

  Conditional:

      UNTIL cond-exp
            [ statement ]...
      NEXT

  Statement Modifier:

      statement UNTIL cond-exp