Problem about LDP Message type

 I saw the following sentences in the draft(draft-ietf-mpls-ldp-06.txt):

"" An LDP Message is malformed if:

     - The Message Type is unknown.

       If the Message Type is < 0x8000 (high order bit = 0) it is an
       error signaled by the Unknown Message Type Status Code.

       If the Message Type is >= 0x8000 (high order bit = 1) it is
       silently discarded.


Any value of Message type(error for <0x8000,discard for >=0x8000) causes
LDP message Type unknown,
then which values
are known for message type?