Note: This ballot was opened for revision 07 and is now closed.
Summary: Needs a YES. Has enough positions to pass.
Comment (2009-12-01) 
Section 3
> Keywords intended for common use SHOULD start with the "$" prefix.
> (Note that this is a SHOULD because some of the commonly used IMAP
> keywords in widespread use don't follow this convention.)
As discussed, you could insist that all new keywords intended for common use
MUST start with the "$" prefix as a definition of the registry.
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Nits
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Through-out
"IMAP Keywords" of "IMAP keywords" ?
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Section 2
"cross client interoperability"
What have the clients to be cross about?
Try "cross-client"
Comment (2009-12-02) 
Section 3., paragraph 21:
> Registration of an IMAP keyword intended for common use (whether or
> not they use the "$" prefix) requires Expert Review [RFC5226]. After
> allowing for at least two weeks for community input on the designated
> mailing list (as described above), the expert will determine the
> appropriateness of the registration request and either approve or
> disapprove the request with notice to the requestor, the mailing
> list, and IANA. Any refusal must come with a clear explanation.
Is list input & the required delay really necessary? Don't we trust
the experts to do the right thing?
Section 3., paragraph 22:
> The IESG appoints one or more Expert Reviewer, one of which is
> designated as the primary Expert Reviewer. IMAP keywords intended
> for common use SHOULD be standardized in IETF Review [RFC5226]
> documents.
What does "primary" mean? Nowhere else in this document is described
what sets this experts apart from the others. (Suggest to simply
remove this.)
Section 3.2., paragraph 1:
> Once an IMAP keyword registration has been published by IANA, the
> author may request a change to its definition.
Who is the "author"? Do you mean the owner?
Section 3.2., paragraph 4:
> IMAP keyword registrations may not be deleted; keywords which are no
> longer believed appropriate for use can be declared OBSOLETE by a
> change to their "intended usage" field.
I believe HISTORIC would be more correct (whenever we say "obsolete"
we usually saw obsoleted by *what*).