The MCI_BREAK_PARMS structure contains virtual-key code and window information for the MCI_BREAK command.
typedef struct {
    DWORD dwCallback; 
    int   nVirtKey; 
    HWND  hwndBreak; 
} MCI_BREAK_PARMS; 
 When assigning data to the members of this structure, set the corresponding flags in the fdwCommand parameter of the mciSendCommand function to validate the members. The following flags are defined:
  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in mmsystem.h.
MCI Overview, MCI Structures, MCI_BREAK, mciSendCommand