TWMDDE_Ack = packed record
  Msg: Cardinal;
  PostingApp: HWND;
  case Word of
    WM_DDE_EXECUTE: (PackedVal: Longint;);
    WM_DDE_INITIATE: (App: Word;
                      Topic: Word;
                      Result: Longint;);
end;

struct TWMDDE_Ack {
  unsigned Msg;
  HWND PostingApp;
  Word App;
  Word Topic;
  Longint Result;
  Longint PackedVal;
};