3.1.5.3 Processing Authentication Server-Instructed Update Messages

The client MUST compare the version number of its stored Passport Configuration Data (as specified in section 3.1.1) to the version number supplied in this message. If the client's stored version number is lower than the version number supplied in the message, the client MUST issue an HTTP GET to the configuration server URL (as specified in section 1.5). Handling of the response to this HTTP GET message is specified in section 3.1.5.4.