This called the component's open function to allocate and initialize any necessary storage for the instance.
These references were generated in such a way that, once they became invalid, those values were unlikely to become valid again for a long time.
Components were identified by OSType codes giving their type, subtype and "manufacturer".
For instance, a component type might be "raster image compressor", subtypes of which might exist for JPEG, H.261, Sorenson, and Intel Indeo, among others.
It was possible for the applications to query the existence of such alternatives and make explicit choices between them, or let the system choose a default.