An application using DDE-based OLE can use three new items for the System topic: the Topics item, the Protocols item, and the Status item.
The Topics item returns a list of DDE topic names that the server application has open. Where topics correspond to documents, the topic name is the document name.
The Protocols item returns a list of protocol names supported by the application. The list is returned in tab-separated text format. A protocol is a defined set of DDE execute strings and item and format conventions that the application understands. The protocol currently defined for linked and embedded objects is the following:
Protocol: StdFileEditing commands/items/formats
For compatibility with client applications that were written before the implementation of the OLE protocol, server applications that use the DDE protocol directly should also include the string Embedding in the list of protocols.
The Status item is a text item that returns Ready if the server is prepared to respond to DDE requests; otherwise, it returns Busy. This item can be queried to determine if the client should offer such functions as one that gives the user an opportunity to update the object. Because it is possible that a server could reject or defer a request even if Status returns Ready, client applications should not depend solely on the Ready item.