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
002	RegCreateKey
003	RegCloseKey
004	RegDeleteKey
005	RegSetValue
006	RegQueryValue
007	RegEnumKey
008	WEP	Done
009	DragAcceptFiles
011	DragQueryFile
012	DragFinish
013	DragQueryPoint
020	ShellExecute
021	FindExecutable
022	ShellAbout	Show standard About dialog	Done
033	AboutDlgProc	About Dialog Window Procedure	Done
034	ExtractIcon
036	ExtractAssociatedIcon
037	DoEnvironmentSubst
038	FindEnvironmentString
039	InternalExtractIcon
101	DLLEntryPoint
102	RegisterShellHook
103	ShellHookProc
Group	Functions
Module manager	GETVERSION GETMODULEHANDLE GETMODULEUSAGE GETMODULEFILENAME GETPROCADDRESS MAKEPROCINSTANCE FREEPROCINSTANCE GETINSTANCEDATA CATCH THROW GETCODEHANDLE LOADLIBRARY
Global Memory Manager	GlobalAlloc GlobalCompact GlobalDiscard GlobalFree GlobalLock GlobalReAlloc GlobalSize GlobalUnlock GlobalFlags
Local Memory Manager	LocalInit 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	_lopen _lcreat _llseek _lread _lwrite _lclose OpenFile GetTempFileName GetTempDrive
Registry	RegOpenKey RegCreateKey RegCloseKey RegDeleteKey RegSetValue RegQueryValue RegEnumKey
Dialogs	MessageBox