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Chapter 3

Important Concepts for Character

Coding Systems

Character coding system is one of the fundamental elements of the software and information

processing. Without proper handling of character codes, your software is far from realization of

internationalization. Thus the author begins this document with the story on character codes.

In this chapter, basic concepts such as coded character set and encoding are introduced. These terms

will be needed to read this document and other documents on internationalization and character

codes including Unicode.

3.1 Basic Terminology

At first I begin this chapter by defining a few very important word.

As many people point out, there is a confusion on terminology, since words are used in various

different ways. The author does not want to add a new terminology to a confusing ocean of

various terminologies. Otherwise, terminology of RFC 2130 (

http://www.faqs.org/rfcs/

rfc2130.html

) will be adopted in this document, besides one exception of a word 'character

set'.

Character Character is an individual unit of which sentence and text consist. Character is an

abstract notion.

Glyph Glyph is a specific instance of character. Character and glyph is a pair of words. Some 

times a character has multiple glyphs (for example, '$' may have one or two vertical bar.

Arabic characters have four glyphs for each character. Some of CJK ideograms have many

glyphs). Sometimes two or more characters construct one glyph (for example, ligature of