This is part of Win16 API which allow to create versions of program from one source code to run under OS/2 and Win16. Under OS/2 program can be running under Win-OS/2 if program is Windows NE executable, and with help on Windows Libraries for OS/2, if it is OS/2 NE executable. Here is a WLO to OS/2 API mapping draft
Sends a message to an installable driver.
LRESULT WINAPI SendDriverMessage(HDRVR hDriver, UINT message, LPARAM lParam1, LPARAM lParam2);
Handle to the installable driver.
Driver-specific message. DRV_LOAD, DRV_ENABLE, DRV_OPEN, DRV_CLOSE, DRV_DISABLE, DRV_FREE, DRV_INSTALL, DRV_QUERYCONFIGURE, DRV_CONFIGURE, DRV_REMOVE, DRV_RESERVED, DRV_USER.
First message parameter.
Second message parameter.
Returns nonzero if successful or zero otherwise.
The exact meaning of parameters depends on the driver.
LRESULT result = SendDriverMessage(hDriver, DRV_OPEN, 0, 0);
push lParam2 push lParam1 push message push hDriver call SendDriverMessage