(form "00661" (size 50 6)
  (help "00661_TIP_0")
  (heading "OPTIMISATION TOLERANCE")
  (label (position  2  3) (text "Tolerance distance"))
  (field "tol_val" (position 25  3) (display_length 20) (input allowed)
    (format real_8) (low_bound 0.001) 
    (default "0.5") (null disallowed) (max_length 20)
    (help "00661_TIP_1")
  )
  (default_buttons)
)