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
Closes an installable driver.
LRESULT WINAPI CloseDriver(HDRVR hDriver, LPARAM lParam1, LPARAM lParam2);
Handle to the driver to close.
First close parameter.
Second close parameter.
Returns nonzero if successful or zero otherwise.
The exact meaning of parameters depends on the driver.
CloseDriver(hDriver, 0, 0);
push lParam2 push lParam1 push hDriver call CloseDriver