Unicode Explained

programs and subroutine libraries, which let you use the information in programs

that you design.

Figure 5-1

illustrates the use of an online service, Uniview, for viewing some key prop-

erties of characters with a graphic user interface. In the figure, the character itself is

shown on the right, with some property values listed under it. Uniview lets you browse

and search characters by general category or other properties. Uniview is available at

http://people.w3.org/rishida/scripts/uniview/.

Character Classification

We will first consider one important property of characters in Unicode, namely General

Category (or gc, for short). This will illustrate the definition and usefulness of prop-

erties, as well as some problems in defining them.

The Purposes of Classification

Characters can be classified in several ways, for different purposes. The Unicode stand-

ard defines a basic classification by assigning the General Category property to each

character. Other properties imply classifications that are more specific, such as by the

“age” of character—i.e., by the Unicode version in which it was encoded.

The General Category property, defined for all characters, constitutes a fundamental

classification into letters, numbers, punctuation, mathematical symbols, etc. For sev-

Figure 5-1. Viewing characters and their properties in Uniview

216 | Chapter 5: Properties of Characters

eral frequently used ...