This function enables an application to query the memory model associate with a particular window to find out whether or not conversion of application-defined data is required. This may be necessary, for example, when sending DDE data. An existing OS/2 Version 1.1 or 1.2 application does not know about pointer conversion, so its data has to be converted for use in a 32-bit application.

The memory model is determined by how the window procedure was registered. If an application calls WinRegisterClass from 32-bit code, any windows created with that class are called 32-bit windows. If the application calls WinSubclassWindow from 16-bit code on a 32-bit window, that window becomes a 16-bit window.