2 Background

To its user, a compound document appears to be a single unit of information, but in fact it can contain elements created by different applications. A compound document could, for instance, consist of a spreadsheet and several images embedded into a text document.

In the general case, every data type in a compound document (spreadsheet, text, image, sound, etc.) is created and managed by a different application. The different applications used to create the document can be thought of as software components that provide services that are invoked to create, edit, and display the compound document.

In the remainder of this section we review the technologies used by Office to enable compound documents. We start with an overview of COM, OLE, and Automation. We then talk about the two native file formats supported by Office. Finally, we present a taxonomy of components found in Office applications.