Document operations are performed during conversations with an application's OLESystem or System topic. The document's class name is used to establish the conversation.
Data transfer and negotiation operations are performed during conversations with the document (that is, the topic). The document name is used to establish the conversation.
Note that the topic name is used only in initiating conversations and is not fixed throughout the conversation; permitting the document to be renamed does not mean that there will be two names. Therefore, it is reasonable to tie the topic name to the document name.