function checkzip(field)
{
  var valid = "0123456789-";
  var hyphencount = 0;

  if (field.length!=5 && field.length!=10)
  {
//    alert("Please enter your 5 digit or 5 digit+4 zip code.");
    return 1;
  }
  for (var i=0; i < field.length; i++)
  {
    temp = "" + field.substring(i, i+1);
    if (temp == "-") hyphencount++;
    if (valid.indexOf(temp) == "-1")
    {
//    alert("Invalid characters in your zip code.  Please try again.");
    return 2;
    }
    if ((hyphencount > 1) || ((field.length==10) && ""+field.charAt(5)!="-"))
    {
//      alert("The hyphen character should be used with a properly formatted 5 digit+four zip code, like '12345-6789'.   Please try again.");
      return 3;
   }
  }
return 0;
}