Because each human activity that is exposed by the portal is assigned to a task page definition, you need to have a unique Client UI identifier for each staff activity.

It would contain the same activity identifier as Coordinator Ca, but when App2 registers for the Durable2PC protocol to its Coordinator, Cb, its request is forwarded directly to Coordinator Ca.

A short phrase or label for each schedule activity used in conjunction with an activity identifier to differentiate that project schedule activity from other schedule activities.