OS/2 Warp 4 and up include APIs for Unicode support, referred to as the Universal Language Support (ULS) functions. Unfortunately, they are very poorly documented.

Consequently, I have embarked upon a series of projects to make the Unicode support in OS/2 more accessible to developers. These are available below.

Updated Programmer's Reference

The OS/2 Warp 4 Toolkit contained some cursory reference documentation (UNIAPI.INF) for ULS, but this is now severely outdated. Later versions of the Toolkit provide updated documentation in HTML format (UNIAPI.HTM), but it is woefully incomplete, very poorly formatted, and contains some blatant errors.

I have undertaken a major revamping of the ULS API reference documentation. My document is based on IBM's UNIAPI.HTM from the 4.52 Toolkit, but with many improvements:

This document remains a work in progress, as I continue to find areas for improvement. See the below for the change history.

The legal status of this document is a bit muddy. As it is a direct derivation of IBM's own documentation, I do not claim any particular rights over it. As far as I am concerned, it may be freely redistributed and/or modified. IBM's own legal terms regarding modifying or redistributing this documentation are unclear.


You can download the HTML documentation as a ZIP file, or read it online.

New Programmer's Guide

As a companion to the updated reference documentation, I have also written an introductory programming guide that describes how to properly use the Universal Language Support APIs.

This document is in OS/2 INF format. The IPF source is included, to make it easier for anyone who wants to suggest amendments (or for translation, if there's anyone that ambitious).

This document is entirely my own work, and may be redistributed freely.


List of OS/2 Codepages

I have undertaken to create a comprehensive list of all codepages supported by OS/2. These codepages may be used in the ULS API conversion functions.

This table attempts to list every codepage, including aliases, known to modern OS/2 systems. Keep in mind that not all codepages may be available on all systems (depending on the installation options and/or operating system version).

The codepages listed in this table may be used in conjunction with the ULS codepage conversion functions. Many of them are not available for use as system or PM codepages, and will not be listed by the WinQueryCpList() function.

Explanation of Fields

Lists the codepage number. ("OS2UGL" is a special codepage which has no number, and is thus identified by name.)

A brief description of the codepage, including the language or character set standard(s) covered, and any additional information about the encoding format used.

Codepages prefixed with 'IBM' indicate encodings based on modifications of the standard DOS 8-bit ASCII layout, and are not recommended for cross-platform interchange.

Codepages prefixed with 'ISO' are official ISO standards, and may be used for interchange with other systems.

Indicates the underlying encoding of Latin text on which the codepage is based.
  • "ASCII" indicates a PC codepage compatible with the 7-bit displayable ASCII character set.
  • "EBCDIC" indicates an IBM mainframe (System 370/390/iSeries) codepage based on EBCDIC.
  • "Other" indicates a codepage which is not byte-for-byte compatible with either ASCII or EBCDIC. (By definition this includes all fixed-width double-byte codepages.)
Indicates the number of bytes used by the codepage to represent a single character. Fixed-width codepages will show a single integer value; variable-width codepages will show a range.
Indicates whether or not the codepage may be used as an OS/2 process codepage (through the CODEPAGE setting in CONFIG.SYS). This does not take into account the system's COUNTRY setting, which may impose additional restrictions on which codepages may actually be used in this way.
Indicates whether or not the codepage may be used as a display codepage within Presentation Manager (either through WinSetCp() or GPI font attributes).
Additional information about the codepage.


REXX Universal Language Support library — RXULS.DLL

REXX Universal Language Support (RxULS) provides a REXX interface to selected parts of the OS/2 Universal Language Support API (ULS).

Using RxULS, it becomes possible to do the following from REXX:

See the documentation for details.


rxuls_061.zip RXULS.DLL with documentation, examples, and source.

The source code is available via NetLabs SVN under the rexxlibs project. Version 0.61 corresponds to SVN revision 46.

Sample Programs


CPMAP is a simple program that can display a complete character map of any OS/2 codepage (even those which are not available for use as system or PM codepages).

I originally wrote this program to help me create the list of codepages (above). However, it serves as a useful illustration of some of the Unicode APIs. (It can also be handy for debugging fonts.)

In some ways, this program is similar to Ken Borgendale's ShowCP program, although it evolved quite independently. Unlike ShowCP, CPMAP can display any installed codepage, not just a selected few. (Conversely, though, it lacks both print support and a glyph-details mode).

For best results, CPMAP should be used in conjunction with a Unicode outline font. It defaults to using Times New Roman MT 30, which is included in recent versions of OS/2 (Warp Server for e-business and later), and is also available with some versions of Java 1.1.8.

CPMAP is made available under a BSD-style license; see the documentation for details.



cpmap_12.zip Program and source code included.

Unicode Clipboard Demonstration

This is a very simple program that demonstrates how to implement support for the "text/unicode" clipboard format used by the Mozilla family of applications.

The user interface consists only of an MLE (editor) control. If you paste text that was copied from Mozilla (or some other program that supports the same format) into the MLE, it will be converted from UCS-2 (Unicode) into the current codepage. Conversely, text which you copy from the MLE will be converted from the current codepage into UCS-2 format.

No other functionality (loading, saving, printing, etc.) is supported. This program is intended to demonstrate clipboard support, and nothing more.

The source code is included, along with a Makefile for the IBM C Compiler (version 3.x). It may be considered public domain code, and may be freely used for any purpose, commercial or otherwise.




I have a few other programs that use the ULS APIs: