Designing External Systems
As described under What Type Of Workflow Process Is Created?, every notification upload staging (NUS) record contains an external system. An external system is the unique identifier of the sender of the notification.
To "design" your external systems, document the external id's (e.g., DUNS number) of your service providers.
Note: It's obvious, but worth stressing, that the External System
should be the exact number referenced on notifications sent by a sender.