Extended Embedded Objects
Some OLE server applications expose additional functionality through COM Automation. Word, for example, exposes several Automation classes, such as Application and Document. The Document class is the same class that represents an embedded Word document. Therefore, whenever you create an embedded Word document, you're instantiating this Document class. This means that if you use an embedded Word document, you may also use its Automation interface.
While embedded documents themselves are only required to expose two features—rendering themselves and possibly in-place editing—they may expose more features through Automation interfaces. This explains why certain embedded documents do not expose any user-defined methods or properties, while others do.