[Dev] iMip design questions

[Chih-Chao Lam]

At OSAF (www.osafoundation.org), we're developing Chandler, a PIM 
client including email, calendaring and task management applications. 
We are at an early stage of evaluating how we should support iMip and 
had a few design/workflow questions. Lisa Dusseault suggested that this 
forum would be highly useful. I only have a cursory understanding of 
the iCalendar, iTip and iMip RFCs, so apologies if I am not getting 
something obvious. Here're our main queries:

We would like event invitations that can be modified by any attendee 
and rebroadcasted (via email) to all attendees and the organizer of the 
event.
     * Is this possible under iMip?
     * Or is the Organizer the only person that can modify and update 
the event?
     * Are there workarounds to make this possible and yet allow 
interoperability with existing clients?

     * What does iMIP have to say about forwarded invitations?
     * How is forwarded an iMIP invitation different from adding 
attendees to the same invitation?

     * Can an attendee have two different email addresses? and thus 
reply from a different email address from the one specified by the 
organizer?

     * MUST support for iMip mean we have to support S/MIME? (as my 
reading of the spec indicates?)

     * Does iMIP support VJOURNAL in addition to VEVENT and VTASK?

Answers to the above questions are highly appreciated, especially from 
the following 2 context:
    1. What does the theoretical RFCs have to say?
    2. What are the pragmatic interoperability issues with today's 
existing clients?

Thanks,
chao