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

Ordinal	Name	Description	Status	Version
001	RegOpenKey	Open the specified key	3.1
002	RegCreateKey	Create or open the specified key	3.1
003	RegCloseKey	Close a key	3.1
004	RegDeleteKey	Delete the specified key	3.1
005	RegSetValue	Associate a text string with a specified key	3.1
006	RegQueryValue	Retrieve the text string associated with a specified key	3.1
007	RegEnumKey	Enumerate the subkeys of a specified key	3.1
008	WEP	DLL Exit procedure	Done	3.1
009	DragAcceptFiles	Register whether a given window accepts dropped files	Done	3.1
011	DragQueryFile	Retrieve the number of dropped files and their filenames	Done	3.1
012	DragFinish	Release memory that Windows allocated for use in transferring filenames to the application	Done	3.1
013	DragQueryPoint	Retrieve the window coordinates of the cursor when a file is dropped	Done	3.1
020	ShellExecute	Open or print the specified file	3.1
021	FindExecutable	Find and retrieve the executable filename that is associated with a specified filename	3.1
022	ShellAbout	Show standard About dialog	Done	3.1
033	AboutDlgProc	About Dialog Window Procedure	Done	3.1
034	ExtractIcon	Retrieve the handle of an icon from a specified executable file, dynamic-link library (DLL), or icon file	3.1
036	ExtractAssociatedIcon	Retrieve the handle of an icon associated with file type	3.1
037	DoEnvironmentSubst	Parse input string that contains references to one or more environment variables and replaces them with their values	Done	3.1
038	FindEnvironmentString	Return pointer into the DOS environment	Done	3.1
039	InternalExtractIcon	Retrieve handles of icons from EXE, DLL or ICO files	3.1
101	DLLEntryPoint
102	RegisterShellHook
103	ShellHookProc
Group	Functions
Module manager	GETVERSION GETMODULEHANDLE GETMODULEUSAGE GETMODULEFILENAME GETPROCADDRESS MAKEPROCINSTANCE FREEPROCINSTANCE GETINSTANCEDATA CATCH THROW GETCODEHANDLE LOADLIBRARY
Memory Manager	GlobalAlloc GlobalCompact GlobalDiscard GlobalFree GlobalLock GlobalReAlloc GlobalSize GlobalUnlock GlobalFlags LocalAlloc LocalCompact LocalDiscard LocalFree LocalLock LocalFreeze LocalMelt LocalReAlloc LocalSize LocalUnlock LocalHandleDelta LockData UnlockData LocalFlags
Task Scheduler	GetCurrentTask Yield SetPriority
Resource Manager	AddFontResource RemoveFontResource LoadBitmap LoadCursor LoadIcon LoadMenu LoadString LoadAccelerators FindResource LoadResource AllocResource LockResource FreeResource AccessResource SizeofResource SetResourceHandler
String Translation	AnsiUpper AnsiLower AnsiNext AnsiPrev
Atom Manager	InitAtomTable AddAtom DeleteAtom FindAtom GetAtomName
Windows Initialization File	GetProfileInt GetProfileString WriteProfileString
Debugging	FatalExit
File I/O	OpenFile GetTempFileName GetTempDrive
Registry	RegOpenKey RegCreateKey RegCloseKey RegDeleteKey RegSetValue RegQueryValue RegEnumKey