add word NONE to zip in validation

hi @LL,

we are using simple code for validation in zip, but now we want to be able to type the word
"NONE" also.
How this code can be modified to do that?

case 'zip':
if ($inString=='') { appendError("Required Field"); }
else {
$length=strlen($inString);
switch($length)
{
default:
appendError("Must be 5 digit zip '00000', or zip+4 '00000-0000' or 'NONE'");
break;

case '5':
$pattern="^[[:digit:]][[:digit:]][[:digit:]][[:digit:]][[:digit:]]$";
$emailTest=ereg($pattern, $inString);
if (!$emailTest) { appendError("Only numbers allowed in zip"); }
break;
case '7':
$pattern="^[[:digit:]][[:digit:]][[:digit:]][[:space:]][[:digit:]][[:digit:]][[:digit:]]$";
$emailTest=ereg($pattern, $inString);
if (!$emailTest) { appendError("Canadian postal codes must be three digits, one space, three digits"); }
break;
case '10':
$pattern="^[[:digit:]][[:digit:]][[:digit:]][[:digit:]][[:digit:]]-[[:digit:]][[:digit:]][[:digit:]][[:digit:]]$";
$emailTest=ereg($pattern, $inString);
if (!$emailTest) { appendError("Not a valid Zip+4 format"); }
break;




Thanks