The MM_WOM_OPEN message is sent to a window when the given waveform-audio output device is opened.
MM_WOM_OPEN
wParam = (WPARAM) hOutputDev
lParam = reserved
This message does not return a value.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in mmsystem.h.
Waveform Audio Overview, Waveform Messages