Personal Communications Response

Personal Communications receives the Start Session Advise and returns an ACK message if it can start the advise. Otherwise, a negative ACK message is returned to the client with one of the following return codes in the low-order byte of the wStatus field:
WM_DDE_ACK(wStatus, aItem)
Return Code Explanation
1 Advise already active for data item.
6 Advise parameter not valid.
9 A system error occurred.
Once the advise has started, the client receives DATA messages notifying it that the data item (PS, OIA, or TRIMRECT) has changed:
WM_DDE_DATA(hData, aItem)

The DATA messages continue until a Stop Session Advise message is sent to Personal Communications. The format of the data item is the same as if the client requested the data item via a DDE_REQUEST.