// John Michael Pierobon

function checkit(form)
{
var flag = false;
if  (form.zipcode.value == "")
    {
    alert("Please enter your zip code.");
    form.zipcode.focus();
    flag = true;
    }
    else
    if  (form.zipcode.value.length < 5)
        {
        alert("Your zip code must have five digits.");
        form.zipcode.focus();
        flag = true;
        }
        else
        if  (isNaN(form.zipcode.value))
            {
            alert("Your zip code must be a number.");
            form.zipcode.focus();
            flag = true;
            }
switch (form.zipcode.value.substring(0,3)) {
   case "000":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "001":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "002":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "003":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "004":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "213":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "269":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "343":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "345":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "353":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "419":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "428":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "429":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "517":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "518":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "519":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "529":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "536":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "568":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "569":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "578":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "579":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "589":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "621":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "632":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "642":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "643":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "659":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "663":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "682":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "694":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "695":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "696":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "697":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "698":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "699":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "702":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "709":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "715":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "732":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "742":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "817":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "818":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "819":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "839":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "848":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "849":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "851":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "854":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "858":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "861":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "862":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "866":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "867":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "868":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "869":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "876":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "886":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "887":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "888":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "892":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "896":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "899":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "909":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "929":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   case "987":
    alert("Your zipcode appears to be invalid.");
    form.zipcode.focus();
    flag = true;
      break;
   default:
}

if  (flag)
    {
    return false;
    }
    else
        {
        return true;
        }
}