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 | Register system wide Shell Hook | | 3.1 |
| 103 | ShellHookProc | Shell Hook procedure | | 3.1 |
| 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 |
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