I noticed in doing primer work that reference tokens are mandatory in 
channel type definitions. This doesn't make sense when you consider a 
choreography in which no WSDL end points have yet been defined. We 
already have the behavior as optional in the role type definition and 
seems to me that a suitable way forward would be to make the reference 
optional in the channel definition. This would enable choreographies to 
be written that require no WSDl end point to be defined and so promote 
end point skeletal generation.

Cheers

Steve T