The  FOR  statement  repeatedly  executes  a  block  of  statements  while
  incrementing  a  specified  control  variable  for  each  execution of the
  statement block.  FOR loops can be conditional or  unconditional  and  can
  modify other statements.

  Examples

  FOR I% = 1% TO 10% STEP 2%
       .
       .
       .
  NEXT I%
  FOR N% = 5% STEP 4% WHILE 400 - Z < .0001
       .
       .
       .
  NEXT N%
       .
       .
       .
  PRINT I% ** I% FOR I% = 1% TO 3%

1  –  Syntax

  Unconditional:

      FOR num-unsubs-var = num-exp1 TO num-exp2 [ STEP num-exp3 ]

          [ statement ]...

      NEXT num-unsubs-var

  Conditional:

                                                    {UNTIL}
      FOR num-unsubs-var = num-exp1 [STEP num-exp3] {WHILE} cond-exp

          [ statement ]...

      NEXT num-unsubs-var

  Unconditional Statement Modifier:

      statement FOR num-unsubs-var = num-exp1 TO num-exp2 [STEP num-exp3]

  Conditional Statement Modifier:

      statement FOR num-unsubs-var = num-exp1 [step num-
             exp3] {WHILE} cond-exp