User story
Annie from Adelaide Exchange went on holiday and agreed that the accommodation should be paid in local money to Brian from Brisbane exchange.
Ben logs on and goes to the external payment form, where he chooses Adelaide from a list of participating exchanges in the network. He knows Annie's id already and enters

I always hoped, but never really believed, that engineering alone was enough bring a product to the attention of the masses, so I planned to spend this year travelling round Europe, coaxing some more early adopter communities into making the right software choice. But some thing is going right. I hardly even got an interview in the cities I visited, but past learning experiences must be paying off.