Trivial 1. Since "ClientID" was introduced in the previous paragraph, this should be: "The ClientID MUST be present ...":
1174 The Client Identifier (ClientID) MUST be present ...
2. Line 1193 - should be "(Client Identifier not valid)":
1192 If the Server rejects the ClientID it MAY respond to the CONNECT Packet with a CONNACK Return Code
1193 0x85 (Identifier not valid) and then MUST close the Network Connection.