Merge pull request #478 from UlfBj/issue463

Issue 463:Subscription handling on error.

spec/VISSv2_Core.html

@@ -440,10 +440,11 @@ <h2>Subscription</h2>
       <section id="error-message">
         <h2>Error Message</h2>
         <p>The server MUST inform a client about errors ocurring in interactions between the two, whether it is in a synchronous 
-        error response, or an asynchronous error notification as a result of a previous subscribe. 
+        error response, or an asynchronous error event as a result of a previous subscribe. 
         For transport protocols which do not control the logical linking between request and response messages it may not be possible to link an error message to the correct client request. 
         In cases like this the server may omit sending an error message. 
-        The error message has three arguments, of which subscriptionId is mandatory only for error notifications.
+        The error message has three arguments, of which subscriptionId is mandatory only for error events.
+        In the case of an error event being issued by the server, the associated subscription session SHALL thereafter be terminated by the server.
         </p>
           <p>Arguments: 
             <ul>