For a display hook's DLL to be installed, the name of the DLL must be added to OS2.INI with keyname = MODULENAME and application name = PM_ED_HOOKS.

The graphics engine will load the DLLs so identified in OS2.INI in turn, from left to right, so that the rightmost name will be the last display hook's DLL offered access to the dispatch tables.

Display hook DLLs need to be Ring-2-conforming. Support for 16-bit drivers runs at Ring 2. OS/2 2.0 32-bit drivers have a choice to run predetermined calls at Ring 2.