// ===================================================================
// Javascipt postcode validation routine
// ensure postcode is valid, or report error and blank the field
// ===================================================================
function validatePostcode(obj){ //check postcode format is valid
 rc = true;
 test = obj.value; 
 size = test.length;
 test = test.toUpperCase(); //Change to uppercase
 while (test.slice(0,1) == " ") //Strip leading spaces
  {test = test.substr(1,size-1);size = test.length
  }
 while(test.slice(size-1,size)== " ") //Strip trailing spaces
  {test = test.substr(0,size-1);size = test.length
  }
 obj.value = test; //write back to form field
 if(test == ""){
	return true;
 }
 if (size < 6 || size > 8){ //Code length rule
  alert(test + " is not a valid postcode - wrong length");
  obj.value = "";
  return false;
  }
 else if (!(isNaN(test.charAt(0)))){ //leftmost character must be alpha character rule
   alert(test + " is not a valid postcode - cannot start with a number");
   obj.value = "";
   return false;
  }
 else if (isNaN(test.charAt(size-3))){ //first character of inward code must be numeric rule
   alert(test + " is not a valid postcode - alpha character in wrong position");
   obj.value = "";
   return false;
  }
 else if (!(isNaN(test.charAt(size-2)))){ //second character of inward code must be alpha rule
   alert(test + " is not a valid postcode - number in wrong position");
   obj.value = "";
   return false;
  }
 else if (!(isNaN(test.charAt(size-1)))){ //third character of inward code must be alpha rule
   alert(test + " is not a valid postcode - number in wrong position");
   obj.value = "";
   return false;
  }
 else if (!(test.charAt(size-4) == " ")){//space in position length-3 rule
   alert(test + " is not a valid postcode - no space or space in wrong position");
   obj.value = "";
   return false;
   }

 count1 = test.indexOf(" ");count2 = test.lastIndexOf(" ");
 if (count1 != count2){//only one space rule
   alert(test + " is not a valid postcode - only one space allowed");
   obj.value = "";
   return false;
  }

return rc;
}