A custom implementation of the "IBM437" character set.
This is the original IBM PC character set for the USA, also known as
"CP437", and is used as the default charset by TrueZIP's archive
driver for the ZIP file format.
This implementation is required because this character set may not be
installed in the JRE.
In Sun's JRE, if installed, it's contained in lib/charsets.jar
in the JRE home directory.