Reviewed some TODO's by Peter:

TODO: [PW] Revise use of MUST, SHOULD, COULD, etc. It seems SHOULD and
SHOULD NOT is used when MUST/MUST NOT should be used. RECOMMENDED
should be SHOULD.

resolution by YD: revised some of them. Others are intentional.

TODO: Should be in section Implementation Notes. This section is for
the protocol schema, not the schemas used for compression.

resolution by YD: moved to implementation notes in the previous
commit.

TODO: [PW] Why not efficient? In terms of total amount of
communication performed during a device's lifetime, its a very very
small fraction (insignificant).  This is a subjective opinion, termed
in absolute phraseology.

resolution by YD: Some phrase are added to describe the problem of
diversity.
Added new implementation notes section to describe XML model modification between XML and EXI.
minor bug fix.
Updates according to discussion with Peter
Added XML samples and corresponding EXI streams (however, the streams are not good because the schema is not yet fixed.)
Added some examples on initial negotiations of alternate transport (again, EXI is not good until the schema is fixed.)
some more descriptions on initial communications are added.
Merge pull request #2 from d0i/topic-ydedit-update-20130521

Topic ydedit update 20130521made by Joachim Lindborg