You define this instance with reference to the interface i_oi_document_proxy:

Each instance document controls a document that you open in the office application. If you want to open more than one document at once, you must define a separate instance for each document.

You can also use methods to open, close, save, and edit documents in your office application programs.

Before you create the instance document , you must create the central instance control for managing the Desktop Office Integration.