This is pretty ugly, but it seems to work.

code:
do
   $gotIt = 0
   cls
   gets $x
   select
      case len($x) = 4
         if val(substr($x, 1, 3)) >= 100 and val(substr($x, 1, 3)) < 1000 and instr("abcde", substr($x, 4, 1))
            $gotIt = 1
         endif
      case len($x) = 5
         if val(substr($x, 1, 4)) >= 1000 and val(substr($x, 1, 4)) < 10000 and instr("abcdef", substr($x, 5, 1))
            $gotIt = 1
         endif
         
      case(1)
         ;nothing
   endselect
until $gotIt
_________________________
Eric