This provides a detailed list of the external interfaces and data transfers between the application and other applications, hardware devices, or other outside organizations. Typically, these are serial data files received, created, or transmitted from within a batch process or program. Also provides the support analyst a detailed list of external interfaces between the application and external environment. This document identifies the program producing the file, record format name, frequency and relative size in records produced. This is invaluable when there is a problem or change to the interface. If a file is not produced/received, it gives a very good starting point for fault analysis.