...
How can OSIDs possibly define everything I need? It doesn't. OSIDs define the integration issues around many service domains along with some common data in these service domains. All of the "objects" are extensible in such a way that methods and data may be added outside its core specification. There's plenty of room to add your own stuff and have interoperability through the core specifications. Like development methodologies, the concept of interoperability is a bit more nuanced than yes/no.