Questions about IOTP 1.0

[Cullen Jennings <[e-mail]>]

I apologize in advance for these naive questions but I'm just trying to get
up to speed on IOTP. If there is an implementers lists or a better list to
ask them on - please point me that way. I'm looking at this for use with
VoIP applications. 

In an OfferRespBlk, you can have a Payment which contains a BrandListRef but
I don't see how to put a BrandList in an OfferRespBlk. The text in section
3.2.1 about offer exchanges indicates that organization such as the Merchant
and Payment Handler can be indicated in the OfferRespBlk but again, I don't
see how to do that. Are both of these solved by putting them in a TpoBlk in
the same IotpMessage?

The DeliveryReqBlk is described in section 2.2.3 as having a Payment Receipt
Signature.  I don't see how to include that. It also seems that the actually
Payment Receipt is needed so that the Delivery service and validate the
signature but I don't see any mention of including a PayReceipt in the
DeliveryReqBlk. Even if signatures are not being used, it seems very
desirable to have the Payment Receipt available in the Delivery Request. Is
there a way to do this?

I'm confused about how HMAC works as a signature algorithm.

Our there common interoperation tests folks implementing this do? Interop
events? Common implementations that are good to test against? Open source
implementations? Operational deployments? There seem to be really a lot of
typos in the RFC. Do people recommend to use this in new things or is it
just an historical document?

Many Thanks, Cullen