mariadb/sql/share/charsets/README

This directory holds configuration files which allow MySQL to work with
different character sets.  It contains:

*.conf
    Each conf file contains four tables which describe character types,
    lower- and upper-case equivalencies and sorting orders for the
    character values in the set.

Index
    The Index file lists all of the available charset configurations.

    THE ORDER OF THE CHARACTER SETS IN THIS FILE IS SIGNIFICANT.
    The first character set is number 1, the second is number 2, etc.  The
    number is stored IN THE DATABASE TABLE FILES and must not be changed.
    Always add new character sets to the end of the list, so that the
    numbers of the other character sets will not be changed.

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 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 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.  Comments start with a '#' character and
    proceed to the end of the line.  Words are separated by arbitrary
    amounts of whitespace.

    For the character set configuration files, every word must be a
    number in hexadecimal format.  The ctype array takes up the first
    257 words; the to_lower, to_upper and sort_order arrays take up 256
    words each after that.

    The Index file is simply a list of the available character sets.