Some of the API functions for structured storage are helper functions that perform a sequence of calls to other API functions and interface methods. You can use these helper functions as short cuts.
Other API functions provide access to COM's implementation of structured storage, Compound Files.
Still another set of API functions enable you to convert OLE 1 objects to structured storage. You can use these functions to determine if an object class is from OLE 1 and to convert objects between OLE 1 and current COM storage formats.
Finally, there are API functions for converting and emulating other objects. These functions provide services for one server application to work with data from another application. The data can be converted to the native format of the server application by reading the data from its original format but writing it in the native format of the object application. Or the data can remain in its original format while the server application both reads and writes the data in its original format.