Unicode Explained

CHAPTER 4

The Structure of Unicode

This chapter is an in-depth presentation of the fundamentals of Unicode, including

design principles, coding space, and special terminology. Unicode’s nature as an um-

brella standard based on a large number of older standards and its relationship to ISO

10646 will be described, examining both the unification principle and criticism of it.

However, to divide the complexity to manageable pieces, we postpone the discussion

of properties of characters (including, for example, normalization) and the Unicode

encodings to the next two chapters.

Design Principles

Here we will start from the proclaimed design principles of Unicode. Later there will

be some critical notes and considerations. We will first consider the very general, slo-

gan-like expressions of the goals, and then the more technical principles.

Goals: Universality, Efficiency, Unambiguity

The Unicode standard itself says that it was designed to be universal, efficient, and

unambiguous. These slogans have real meaning here, but it is important to analyze

what they mean and what they do not mean. Let us first see how they are presented in

the Unicode standard, and then analyze each item:

The Unicode Standard was designed to be:

Universal. The repertoire must be large enough to encompass all characters that are likely

to be used in general text interchange, including those in major international, national, ...