This method returns the document cookie (ID of the document). You can use this in a VB add-in to check whether the document exists. If it does, you can then use the methods of the add-in to work with the document.

In the data model of SAP Desktop Office Integration, the document ID is found under:

Application.Documents.Container.DocumentCookie

CALL METHOD document->get_document_cookie
     IMPORTING document_cookie = document_cookie.