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
Win16 personality
Introduction
Win16 Personality for osFree is planned to be implemented as Windows clone based on various sources. Most notable is HX-DOS Extender for KERNEL, Wine and Twin for USER and other core DLLs. GDI.EXE not handled yet. Applications collected and backported to Win16 from ReactOS and Wine implementations.
