From Lisa Dusseault:

Section 4.3.2:  The paragraph beginning "For all other message types" is very
confusing to me and I still don't understand it.  The first sentence sounds like
it's relegating all further information on message processing to another
section, but then the paragraph continues to talk about the rest of the message.
 I can't see whether these four sentences in the paragraph are four random facts
put together spatially or somehow relate together semantically as well.