Because of the added driver support, presentation drivers have a smaller subset of mandatory functions. These mandatory functions differ between display and printer drivers. All drivers are still required to handle the Enable subfunctions and a subset of the DEVESC_functions. One new mandatory function is required - OS2_PM_DRV_ENABLE: Subfunction 0Eh - QueryDeviceSurface. This function provides to the graphics engine the information needed for handling the new Device Driver Interface architecture. This call is made from the graphics engine during an OpenDC call.