Required command messages are supported by all MCI devices. These messages open, close, and obtain information about devices.
MCI_CLOSE
Sent by an application to request that the specified device be closed.
MCI_GETDEVCAPS
Sent by an application to obtain information about device capabilities.
MCI_INFO
Sent by an application to obtain information about a device.
MCI_OPEN
Sent by an application to open a device and get an MCI device identifier for use with other commands.
MCI_STATUS
Sent by an application to obtain status information about a device.