OLE structured storage is a hierarchical storage system that resembles a file system within a file. There are two levels of storage in the storage system:
These objects are analogous to the directory level in a typical file system. A storage object can contain streams and/or other storage objects; a stream object contains data. Each object is assigned its own storage object. Objects and data within the storage system are accessed through a set of interfaces provided by OLE. OLE provides an implementation of this storage system that it calls compound files.
Figure 5.10 Storage and Streams