Prior to establishing a DDE conversation, the target should determine the source-supported formats in which it wants to have the object rendered. It should register this format in the system atom table and use the resulting atom in the usFormat field of the DDESTRUCT used in the conversation.

The target should establish the DDE conversation by posting a WM_DDE_REQUEST message to the window indicated by the hwndItem field in the DRAGITEM data structure. The target acts as the client, and the source acts as the server in the conversation.