pData (PDDEINIT)
This points to a DDEINIT structure. pszAppName is the name of the responding server application; it must not be a zero-length string. pszTopic is the name of the topic that the server is willing to support; it must not be a zero-length string.
The DDEINIT structure must be in a shareable segment; it is the responsibility of the receiving window procedure to free this segment.