This directory holds configuration files that enable MySQL to work with different character sets. It contains: charset_name.xml Each charset_name.xml file contains information for a simple character set. The information in the file describes character types, lower- and upper-case equivalencies and sorting orders for the character values in the set. Index.xml The Index.xml file lists all of the available charset configurations, including collations. Each collation must have a unique number. The number is stored IN THE DATABASE TABLE FILES and must not be changed. The max-id attribute of the <charsets> element must be set to the largest collation number. Compiled in or configuration file? When should a character set be compiled in to MySQL's string library (libmystrings), and when should it be placed in a charset_name.xml configuration file? If the character set requires the strcoll functions or is a multi-byte character set, it MUST be compiled in to the string library. If it does not require these functions, it should be placed in a charset_name.xml configuration file. If the character set uses any one of the strcoll functions, it must define all of them. Likewise, if the set uses one of the multi-byte functions, it must define them all. See the manual for more information on how to add a complex character set to MySQL. Syntax of configuration files The syntax is very simple. Words in <map> array elements are separated by arbitrary amounts of whitespace. Each word must be a number in hexadecimal format. The ctype array has 257 words; the other arrays (lower, upper, etc.) take up 256 words each after that.