Specifying Character Sets

XML Developers,

I am working on a small schema language for an XML language that I
will be using in an open source program. In this schema I am defining
a text data type. I want the schema developer using my schema language
to have the option of specifying the character set of the text data
type.

Is there a standard set of character set names and descriptions that I
can reference?

What is the best approach to this problem? I don't want to create a
new solution if it is unnecessary.

Thanks for the help.

Scott Huey