ISO Development Environment
The ISODE software (pronounced eye-soo-dee-eee), more formally the ISO Development Environment, was an implementation of the OSI upper layer protocols, from transport layer to application layer, which was used in the Internet research community to experiment with implementation and deployment of OSI during the late 1980s and early 1990s. The ISODE software was initially a public domain / open source implementation, led by Marshall Rose.
Source: Wikipedia — ISO Development Environment (CC BY-SA 4.0)