The client terminates a data link by posting a WM_DDE_UNADVISE message to the server, as shown in the following code fragment:

WinDdePostMsg(hwndServer,              /* Handle of server      */
              hwndClient,              /* Handle of client      */
              WM_DDE_UNADVISE,         /* Message               */
              pddeStruct,              /* Shared-memory pointer */
              DDEPM_RETRY);            /* Retry                 */