Perform mapping of roles

Hi

In section 2.5.3, the syntax for mapping of roles in the bind statement implies that the mapping is inconjunction with the variables being bound - however the text implies that the binding of variables is independent of the binding of roles.

This needs to be clarified - e.g. if we wanted to map two variables, but only one role, how would this be encoded?

Alternatively, there is a coupling between the variables and roles, in which case the text is not clear.

I also think we need to have text and example to explain why binding roles is relevant. I guess it is to make the performed choreography more re-usable - but the only situation I can see this happening is if two separate participant types, with their own role types, use a common interface - and then the performed choreography references a third role type (possibly participant independent) that also uses that same interface. In this case, both participants can make use of the performed choreography by mapping their local role type to the common role type. Is this the reason for having this role mapping? Is this complexity necessary?

Regards
Gary