Using the character set description (charmap) source file, you can assign symbolic names to character encodings.
Developers of character set description (charmap) source files can choose their own symbolic names, provided that these names do not conflict with the standardized symbolic names that describe the portable character set.
The charmap file resolves problems with the portability of sources, especially locale definition sources. The standardized portable character set is constant across all locales. The charmap file provides the capability to define a common locale definition for multiple code sets. That is, the same locale definition source can be used for code sets with different encodings of the same extended characters.
A charmap file defines a set of symbols that are used by the locale definition source file to refer to character encodings. The characters in the portable character set can optionally be included in the charmap file, but the encodings for these characters should not differ from their default encodings.
The charmap files are located in the /usr/lib/nls/charmap directory.