Once the neighboring systems are defined, the system interface model attempts to characterize how the systems interact. Assuming compatibility is important, this information implies requirements on the solution.

Since the system interface model implies requirements to the solution, an inadequate or missing model means that requirements could be missed, causing the solution to not meet the needs of the customer.

1. For each neighboring system, how does it exchange information with the current solution?

2. For each neighboring system, in what format does it exchange information? 

3. For each neighboring system, how often does it exchange information? 

4. For each neighboring system, what is the impact of not exchanging information and what recovery methods should be employed?

System Interface Model –A diagram with narrative showing the relationship between the solution and the neighboring system, the frequency of exchange, format of exchange and risk management on failure to exchange.