Change field text USPS shipping

I found a post in this forum on how to change the USPS text in the cart from "Priority" to "Standard" using this line of code in the USPS.php file:

$result = curl_exec($curl);
$result=str_replace('<MailService>Priority Mail','<MailService>Standard',$result);

How would I change "Priority Mail Express 1-Day Flat Rate Envelope" to "Priority Mail Express 1-Day"?

I have searched through the Web API documentation at USPS but I cannot find the proper xml description.

I found a post in this forum

Forum topic unspecified. No OC version posted.