The WD should be consistent about capitalizing the first characters of "special" terms such as "Protocol Error". This needs an editing pass.

Even within the same paragraph, there's variation. For example, see "Will message" and "will message" below:

1045 If the Will Delay Interval is absent, then there is no delay before the will message is published.
1046
1047 Non normative comment
1048 The Server delays publishing the Client’s Will message until the Will Delay Interval has passed or
1049 the Session ends. One use of this is to avoid publishing will messages if there is a temporary
1050 network disconnection and the Client succeeds in reconnecting and continuing its Session before
1051 the Will message is published.
1052