This section defines the terms used to discuss international text handling on the Mac OS. If you would like a more detailed introduction to Mac OS text handling, see "Introduction to Text on the Macintosh," available on the Apple Developer Connection website, under "Text" in the Documents Index.
http://developer.apple.com/techpubs/macos8/Indexes/documentindex.html
For more information on Unicode and related topics, see "Supporting Unicode Input," available on the Carbon Developer Documentation website, in the Unicode Utilities section under "Text and Other International Services."
http://developer.apple.com/techpubs/macosx/carbon/