10.11. History and Recommended Resources
Identifying a software system's public operations is a very old need, so variations of system interface diagrams that illustrate the I/O events for a system treated as a black box have been in widespread use for many decades. For example, in telecommunications they have been called call-flow diagrams. They were first popularized in OO methods in the Fusion method [Coleman+94], which provided a detailed example of the relationship of SSDs and system operations to other analysis and design artifacts.