The enable entry point is exported as OS2_PM_DRV_ENABLE by the presentation driver. The Enable routine in the driver supports a set of subfunctions that enable or disable the environment for a device context owned by a specific application or process. When a device context is opened or closed, the Presentation Manager interface issues a series of calls to subfunctions at the enable entry point. These calls initialize the presentation driver, the physical device, and the device context.

The syntax used by the Presentation Manager interface to call the Enable routine is:

LONG APIENTRY OS2_PM_DRV_ENABLE (Subfunc, Param1, Param2)

ULONG   Subfunc;
ULONG   Param1;
ULONG   Param2;

Note: LONG, ULONG (unsigned LONG), and APIENTRY are defined in OS2DEF.H, which is included through the header file OS2.H.