[ietf-dkim] signature h= and z= tags

I need clarification with the DKIM-Signature: tags:

    h=
    z=

1) Can z= include headers that are not listed in h= and vice versa?

For example, a signature has:

   h=Content-Type:From:Subject:Content-Transfer-Encoding:MIME-Version;

and

   z=From:aaaaaaaa|Subject:bbbbbbbb|To:ccccccccccccc;

the To: subject is included in z= but not listed in h=

2) If z= is defined, and h= has headers not listed in z=, but exist in the
822 headers, what do you do here for validating the hashing?

For example, Content-type:, Content-Transfer-Encoding:, and MIME-Version:
are in h= but not in z=  but the three headers do exist in the email
headers.

3) Why so complex?

--
Hector Santos, Santronics Software, Inc.
http://www.santronics.com








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