The MM_MCISIGNAL message is sent to a window to notify an application that an MCI device has reached a position defined in a previous signal (MCI_SIGNAL) command.
MM_MCISIGNAL
wParam = (WPARAM) wID
lParam = (LONG) lUserParm
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 Messages, signal, MCI_SIGNAL