Legacy Document

Inside Macintosh: Text /

Chapter 1 - Introduction to Text on the Macintosh / Macintosh Text Overview

Writing Systems and Script Systems

Localization is the process of adapting software to local use. When a version of Macintosh system software is created for a particular country or region, its text strings usually must be translated and it must support the writing system of that region. To facilitate the localization of Macintosh system software around the world, much of Macintosh text-handling is concerned with proper presentation in multiple languages. Macintosh computers are sold worldwide, and Macintosh system software is currently available in over 30 localized versions, allowing computer users in many parts of the world to use the Macintosh in their native languages. Macintosh system software likewise provides your application with the capability of simultaneously supporting multiple writing systems.

IMPORTANT

Even if you do not plan to localize your application, it should still support multiple writing systems. Users in your own target region may have capability for more than one writing system on their computers, and may want your application to support that capability.

In this book, a writing system denotes a method used to depict words visually. It consists of a character set and a set of rules for displaying, ordering, and formatting those characters. Writing systems can differ in line direction, the direction in which their characters are read; the size of the character set used to represent the writing system; and whether or not they are contextual--whether a character changes its form depending on its position relative to other characters. Writing systems have specific requirements for text display, text editing, character set, and fonts. A writing system, of which one example is Roman, can serve more than one language, of which two examples are French and Spanish. A single language such as French can have regional variations with slightly different requirements, such as Swiss French and Canadian French. Writing systems
and their features are described under "Features of the World's Writing Systems" beginning on page 1-21.

On the Macintosh computer, a script system (or script for short) is a collection of resources that provides for the representation of a particular writing system. A script's keyboard resources define the character codes and keyboard layout for the writing system, and its international resources provide a host of formatting and ordering rules for the writing system. A script system requires one or more fonts designed specifically for the writing system. The script system is accessed through the Script Manager, the Text Utilities, the script extensions WorldScript I and WorldScript II, and the other text-related software managers described in this book. Together, these software components make up the Macintosh script management system. The files, managers, and resources that make up the script management system are described under "Components of the Macintosh Script Management System" beginning on page 1-35.

A script system on the Macintosh is identified primarily by number, its script code. And just as writing systems can serve several languages, script systems can have variations for different languages, specified by language code. Each language code "belongs" to a particular script code. Regional variations can also be reflected in script systems, by region code. Each region code "belongs" to a particular language code. See, for example, Figure 1-34 on page 1-49.

More than one script system may be enabled, or present and available, on the Macintosh. Script systems may be installed either as auxiliary scripts, which just provide writing-system support, or as the system script, which affects system defaults such as the default font, keyboard layout, line direction, and so forth, and is typically the writing system used for localized dialog boxes, menus, and alerts. All other scripts are secondary to the system script. The font script, also called the current script, is the script system currently being used to draw text. The keyboard script is the script system currently being used for text input.

The Roman script system is always available, either as the system script or as an auxiliary script. Furthermore, the low-ASCII Roman characters are always available in any script system; they are a standard part of every script system's character set.

Macintosh system software routines that take into account the script system of the text they manipulate are called script-aware routines. Likewise, applications that use those routines to properly handle text according to its script system are also called script-aware. Your applications should be script-aware.

More details about script systems and how they work are found under "Components of a Script System" beginning on page 1-40, "How Script Systems Are Classified" beginning on page 1-45, and "How Script Systems Work" beginning on page 1-52.