CESU-8
The Compatibility Encoding Scheme for UTF-16: 8-Bit is a variant of UTF-8 that is described in Unicode Technical Report #26. A Unicode code point from the Basic Multilingual Plane, i.e. a code point in the range U+0000 to U+FFFF, is encoded in the same way as in UTF-8. A Unicode supplementary character, i.e. a code point in the range U+10000 to U+10FFFF, is first represented as a surrogate pair, like in UTF-16, and then each surrogate code point is encoded in UTF-8. Therefore, CESU-8 needs six bytes for each Unicode supplementary character while UTF-8 needs only four.
The encoding of Unicode supplementary characters works out to 11101101 1010yyyy 10xxxxxx 11101101 1011xxxx 10xxxxxx.
CESU-8 is not an official part of the Unicode Standard, because Unicode Technical Reports are informative documents only. It should be used exclusively for internal processing and never for external data exchange.
Supporting CESU-8 in HTML documents is prohibited by the W3C and WHATWG HTML standards, as it would present a cross-site scripting vulnerability.
CESU-8 is similar to Java's Modified UTF-8 but does not have the special encoding of the NUL character.
The Oracle database uses CESU-8 for its "UTF8" character set. Standard UTF-8 can be obtained using the character set "AL32UTF8".Examples
