TheLotus Multi-Byte Character Set (LMBCS) is a proprietarymulti-bytecharacter encoding originally conceived in 1988 atLotus Development Corporation with input from Bob Balaban and others.^[1] Created around the same time and addressing some of the same problems, LMBCS could be viewed as parallel development and possible alternative toUnicode.^[1] For maximum compatibility, later issues of LMBCS incorporateUTF-16 as a subset.^[2][3]

Commercially, LMBCS was first introduced as the default character set ofLotus 1-2-3 Release 3 forDOS in March 1989^[1][4] andLotus 1-2-3/G Release 1 forOS/2^[1] in 1990 replacing the 8-bitLotus International Character Set (LICS) andASCII used in earlier DOS-only versions of Lotus 1-2-3 andSymphony.^[5] LMBCS is also used inIBM/LotusSmartSuite,Notes andDomino,^[1] as well as in a number of third-party products.

LMBCS encodes the characters required for languages using theLatin,^[6]Arabic,Hebrew,Greek andCyrillic^[6] scripts, theThai,Chinese,Japanese^[6] andKorean writing systems, and technical symbols.

Technically, LMBCS is alead-byte encoding where code point 00_hex as well as code points 20_hex (32) to 7F_hex (127) are identical toASCII^[1] (as well as to LICS).^[5]

Code point 00_hex is always treated asNUL character to ensure maximum code compatibility with existing software libraries dealing withnull-terminated strings^[1] in many programming languages such asC.^[a] This applies even to the UTF-16be codes, where code words with the form xx00_hex are mapped toprivate-use codes with the form F6xx_hex during encoding in order to avoid the use of NUL bytes,^[7] and to escaped control characters, where 20_hex is added to the C0 (but not C1) control characters following the 0F_hex lead byte.^[7]

Code points 01_hex to 1F_hex, which serve as control codes in ASCII, are used as lead bytes to switch the definition of code points above 7F_hex between severalcode groups (similar tocode pages) and at the same time determine either a single- or multi-byte nature for the corresponding code group.^[1]

For example, code group 1 (with group byte 01_hex)^[1] is almost identical to theSBCScode page 850, whereas code group 16 (with group byte 10_hex)^[1] is similar to the JapaneseMBCScode page 932. Multi-byte characters can thus occupy two or three bytes.^[7][6]

Incanonical LMBCS, each character starts with its group byte.^[1]To reduce the length, inoptimized orcompressed LMBCS adefault code group oroptimization group code can be defined on a per application or process basis (ideally chosen according to the highest likelihood of occurrence)^[1] and must be communicated to the interpreting code in some way (f.e. by specifying the corresponding "LMBCS-n" name).^[8] Thereby, the group byte can be omitted for these characters.^[1] Lotus 1-2-3 retrieves the optimization group code from the file header of the corresponding source file,^[7] whereas for Lotus Notes the optimization group code is fixed to be always 01_hex.^[2][7]

Without prefix byte the code points 32 (20_hex) to 127 (7F_hex) are interpreted as follows (corresponding to LMBCS codes 32 to 127):

LMBCS group 1 code points 128 (80_hex) to 255 (FF_hex) are identical to the corresponding code points incode page 850 (DOS Latin-1), whereas code points 1 (01_hex) to 127 (7F_hex) are defined according to the following exception list (corresponding to LMBCS codes 256 to 383):

LMBCS group 2 code points 128 (80_hex) to 255 (FF_hex) are identical to the corresponding code points in code page 851 (DOS Greek), whereas code points 1 (01_hex) to 127 (7F_hex) are defined according to the following exception list:^[f]

LMBCS group 6 code points 128 (80_hex) to 255 (FF_hex) are identical to the corresponding code points in code page 852 (DOS Latin-2), whereas code points 1 (01_hex) to 127 (7F_hex) are defined according to the following exception list:^[f]

• Compose key
• GB 18030
• Standard Compression Scheme for Unicode (SCSU)
• Symbol (typeface)
• Xerox Character Code Standard (XCCS)

• Born, Günter[in German] (December 2000) [1990]. "Kapitel 2. LOTUS 1-2-3-Format (WK3)" [Chapter 2. Lotus 1-2-3 WK3 format].Dateiformate – Eine Referenz – Tabellenkalkulation, Text, Grafik, Multimedia, Sound und Internet [File formats – a reference – spreadsheets, text, graphics, multimedia, sound and internet](PDF) (in German). Bonn, Germany:Galileo Computing.ISBN 3-934358-83-7.Archived(PDF) from the original on 2016-11-29. Retrieved2016-11-28. (Includes some information about LMBCS and Lotus system ranges.)
• "LMBCS tables".User's Guide – 123 Release 4 for Windows (Fax). 1995 [1994-01-01]. CHAPTER: Appendix A Using the Lotus Multibyte Character Set. Fax 10955. Retrieved2016-12-06.^{[dead ftp link]}(To view documents seeHelp:FTP)
• "Entering LMBCS characters".User's Guide – 123 Release 4 for Windows (Fax). 1995 [1994-01-01]. CHAPTER: Appendix A Using the Lotus Multibyte Character Set. Fax 10954. Retrieved2016-12-06.^{[dead ftp link]}(To view documents seeHelp:FTP)
• Lotus Support."Notes from Support: SMTP MTA International Character Sets".IBM developerWorks.IBM.Archived from the original on 2016-12-08. Retrieved2016-12-08.
• Character Translation Files (.CTF) by Notes 2.x and Country Language Service (.CLS) files by Notes 3.0 and higher contain information about LMBCS translation into other codepages[2][3]

• Berntrop-Bos, Lars (2014-07-10)."Blast from the past: LMBCS tables for Windows, OS/2, Unix and Macintosh".Archived from the original on 2016-11-26. Retrieved2016-11-26.

• Character encoding
• Character sets
• Computer-related introductions in 1989
• IBM Lotus SmartSuite
• Lotus Software software

• CS1 German-language sources (de)
• CS1 Japanese-language sources (ja)
• Articles with short description
• Short description matches Wikidata
• Articles with wanted Private Use Area characters
• CS1 interwiki-linked names
• Articles with dead FTP links