function CPRchk(form) { 
   var weight = new Array(10)
   	weight[0] = 4
   	weight[1] = 3
   	weight[2] = 2
   	weight[3] = 7
   	weight[4] = 6
   	weight[5] = 5
   	weight[6] = 4
   	weight[7] = 3
   	weight[8] = 2
   	weight[9] = 1

   var sum = 0


   for ( var i = 0; i < form.CPR.value.length; i++ ){
   	sum += form.CPR.value.charAt(i) * weight[i]
   }

   /* Validate CPR.nr. */
   if (sum % 11 == 0){
   	return true
   }
   alert("Invalid CPR no.")
   return false
   
}