function check_integer(field, min, max)
 {
  s = field.value;
  if ( (isNaN(s)) || (s.indexOf('.') > -1) )
   {
    ns = ''; 
    for (var i=0; i<s.length; i++)
     {
      var ch = s.charAt(i);
      if (!(isNaN(ch)))
       {
        ns = ns + ch;
       } 
      }
    if (ns == '') {ns = 0}
    field.value = ns;
   }
  if (field.value < min) {field.value = min}
  if (field.value > max) {field.value = max}  
 }