3.3.5 Message Processing Events and Sequencing Rules
After receiving a CIFS Browser Protocol frame, the opcode MUST first be inspected to determine the message type. If the opcode is not defined in this specification, the frame MUST be silently ignored. If the opcode is recognized, the browser server MUST then determine if the message is correctly formatted as specified in section 2.2. Because messages are transmitted as datagrams, malformed messages MUST be silently ignored.<48>
A browser server MUST ignore the GetBackupListResponse frame. Correctly formed frames MUST then be processed as specified in the following subsections.