function clearform(which){
if ((which.value=="Search") || (which.value=="ZIP Code"))
which.value=''
}

function isBlank() {
value=document.searchbox.elements['sp-q'].value;

if (( value == "" ) || (value == "Search")) {
          alert("Please enter a search keyword.");
          return false;
      }
      else {
      return true;
      }
}