DOCBOOK: author email

[Jack Moffitt <jack@xiph.org>]

I am just starting to regularly use docbook.  And I've run into a slight
snag.

I want to include an email address in the author information.  

It seems that the current way of doing this is:

<author>
<firstname>Jack</firstname>
<surname>Moffitt</surname>
<affiliation>
<address><email>jack@xiph.org</email></address>
</affiliation>
</author>

Now DocBook:TDG 2.0.2 says:

"AuthorBlurb and Affiliation will be removed from the inline content of
Author in DocBook V4.0. A new wrapper element will be created to hold
Author, AuthorBlurb, and Affiliation."

What is this wrapper element?

Also, what happens when two authors have the same affiliation, but wish
to list different email addresses?  Do they each have a shared
affiliation and a unique affiliation with only the email address?  Or
is each author required to have their own affiliation? 

Would it not make more sense to have an <authorinfo> element with
contact information and affiliation as possible children?  Certainly I
may write a document that is not under a certain affiliation but on
which I'd still like to publish my email address :)

Thanks for any help,
jack.