The data in a drag transfer message is carried in a DRAGTRANSFER data structure. DRAGTRANSFER data structures are allocated when the target calls DrgAllocDragtransfer.

When the conversation is completed, both the source and the target must call DrgFreeDragtransfer to free the shared memory. The target should do it immediately after sending a DM_ENDCONVERSATION message. The source should do it immediately after sending a DM_RENDERCOMPLETE message.