Add transactions to BIP 0070

Hello. I hope this is the right way to introduce this...
If we allow full transactions in addition to outputs as methods of specifying payment,
the protocol could handle more complex types of transactions including contracts.
For example, during a negotiation involving rapidly adjusting micro-payments (https://en.bitcoin.it/wiki/Contracts#Example_7:_Rapidly-adjusted_.28micro.29payments_to_a_pre-determined_party), a merchant may want to continuously send an updated version of a transaction to the client in a payment request rather than a new list of outputs every time. 
Any thoughts?