diff --git a/README.md b/README.md
index b58fb942..fd10618f 100644
--- a/README.md
+++ b/README.md
@@ -466,6 +466,8 @@ $response->getMessage(); // a message generated by the payment gateway
 ```
 
 In addition, most gateways will override the response object, and provide access to any extra fields returned by the gateway.
+If the payment authorization is re-usable the gateway will implement ```$response->getCardReference();```. This
+method is always available (but may return NULL) from 3.1.1
 
 ### Redirect Response