oi checks for needed integrations/merges between codelines and notifies of the integration needs. It is useful for automatic notification of needed integrations to keep codelines synced in concurrent development.
For example, it can check for outstanding integrations between a release codeline and the main line (trunk), and email them to a defined address list. It answers the question "are all the changes made to a release codeline merged to the main codeline?"
For another example, oi helps keep project/work codelines up to date with ongoing changes to the main or next release codelines.
oi is an integration/merge "babysitter". Just like a CI (Continuous Integration) product babysits the build, ensuring the build succeeds and tests pass, oi ensures the integrations are done (either integrated or cleared). This is important for a concurrent development environment.