ISO/IEC 8859-11:2001, Information technology — 8-bit single-byte coded graphic character sets — Part 11: Latin/Thai alphabet, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 2001. It is informally referred to as Latin/Thai. It is nearly identical to the national Thai standard TIS-620 (1990). The sole difference is that ISO/IEC 8859-11 allocates non-breaking space to code 0xA0, while TIS-620 leaves it undefined. (In practice, this small distinction is usually ignored.)
ISO-8859-11 is not a main registered IANA charset name despite following the normal pattern for IANA charsets based on the ISO 8859 series. However, it is defined as an alias[1] of the close equivalent TIS-620 (which lacks the non-breaking space), and which can without problems be used for ISO/IEC 8859-11, since the no-break space has a code which was unallocated in TIS-620. Microsoft has assigned code page 28601 a.k.a. Windows-28601 to ISO-8859-11 in Windows.[2] A draft had the Thai letters in different spots.[3]
As with all varieties of ISO/IEC 8859, the lower 128 codes are equivalent to ASCII. The additional characters, apart from no-break space, are found in Unicode in the same order, only shifted from 0xA1 to U+0E01 and so forth.
The Microsoft Windows code page 874 as well as the code page used in the Thai version of the Apple Macintosh, MacThai, are variants of TIS-620 — incompatible with each other, however.