Generalize RP Selection Mechanism

[Cantor, Scott]

And also I see what you meant by the XML baggage...if you actually try and 
implement the interfaces rather than attaching extension data to the data 
model itself, yeah, it's messy work. That's not really the idea of using 
it.

You can totally ignore the XML "heritage" of the data model when you're 
creating the objects directly and just constructing metadata to represent 
the technical requirements.

-- Scott