Create a black box view of your software within its intendend environment. Identify all neighboring systems and specify all logical business data that is exchanged with the system under development.
List of all (a-l-l) neighboring systems.
Understanding the information exchange with neighboring systems (i.e. all input flows and all output flows).
UML-type context diagram - shows the birds eye view of the system (black box) described by this architecture within the ecosystem it is to be placed in. Shows orbit level interfaces on the user interaction and component scope.