For simple character sets in MySQL 4.1, sorting rules are specified in the MYSET.xml configuration file using <map> array elements within <collation> elements. (For MySQL 4.0 or older, the rules are given by the sort_order array in MYSET.conf.) If the sorting rules for your language are too complex to be handled with simple arrays, you need to define string collating functions in the ctype-MYSET.c source file in the strings directory.

The existing character sets provide the best documentation and examples to show how these functions are implemented. Look at the ctype-*.c files in the strings directory, such as the files for the big5, czech, gbk, sjis, and tis160 character sets. For MySQL 4.1, take a look at the MY_COLLATION_HANDLER structures to see how they are used, and see the CHARSET_INFO.txt file in the strings directory for additional information. For MySQL 4.0 or older, look at the CHARSET_INFO structures.