Computers & Writing Systems
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Implementing Writing Systems (The Book)
Table of Contents
The NRSI Model for Implementing Writing Systems
Over its short history, the Non-Roman Script Initiative of SIL International has developed a model for using computers to implement the various writing systems that are needed for text input, storage, processing, and output.
Understanding characters, keystrokes, codepoints and glyphs
Software systems that are used for working with multilingual data are evolving, and it is increasingly important for users and support personnel to have an understanding of how these systems work. This chapter explains some of the most basic concepts involved in working with multilingual text; characters, keystrokes, codepoints, and glyphs. Each notion is explained, as is the way they relate to one another and interact within a computer system.
Character set encoding basics
In understanding technologies for working with multilingual and multi-script text data, we need to start with an understanding of character encoding. Systems for working with text involve a collection of processes that work together—processes for creating and editing text, presenting it, for sorting, for laying out paragraphs and wrapping at line breaks, etc. Character encoding is the thing that ties all of these processes together.
Computer systems employ a wide variety of character encodings. The most important of these for us is Unicode. It is also important for us to understand other encodings, however, and how they relate to Unicode. In this section, I want to look at some basic concepts that relate to all encodings, and also give an overview of legacy encodings and their importance for us.
Understanding Unicode™ - I
Unicode is a hot topic these days among computer users that work with multilingual text. They know it is important, and they hear it will solve problems, especially for dealing with text involving multiple scripts. They may not know where to go to learn about it, though. Or they may have read a few things about it and perhaps have seen some code charts, but they are at a point at which they need to gain a firmer understanding so that they can start to develop implementations or create content. This introduction is intended to give such people the basic grounding that they need.
Understanding Unicode™ - II
Unicode is a hot topic these days among computer users that work with multilingual text. They know it is important, and they hear it will solve problems, especially for dealing with text involving multiple scripts. They may not know where to go to learn about it, though. Or they may have read a few things about it and perhaps have seen some code charts, but they are at a point at which they need to gain a firmer understanding so that they can start to develop implementations or create content. This introduction is intended to give such people the basic grounding that they need.
An introduction to keyboard layout design theory: What goes where?
Designing a keyboard layout is relatively easy: you just allocate codepoints to keystrokes. The difficulty comes when trying to decide what codepoints to assign to what keystrokes. Do you design based around the characters on the keytops of a user's keyboard or the relative position of the keys? What do you do if you want to be able to type more characters than there are keys in your keyboard?
Guidelines for Writing System Support: Technical Details: Smart Rendering: Part 3
Rendering technologies overview
A tour of basic issues related to rendering text for various writing systems, beginning with a simple model and building up to current technologies available for complex rendering.
An Introduction to TrueType Fonts: A look inside the TTF format
The primary font technology used on Microsoft Windows and the Mac OS is based on the TrueType specification. This article examines the function of each of the internal tables that comprise a TrueType font.
Challenges in publishing with non-Roman scripts
There are a number of challenges in the typesetting of non-Roman scripts. These include problems of interaction between the font and typesetting system, problems of very large character sets, and considerations of typesetting the particular script.
Mapping codepoints to Unicode encoding forms
This appendix describes in detail the mappings from Unicode codepoints to the code unit sequences used in each encoding form.
A review of characters with compatibility decompositions
This appendix is intended, therefore, to provide an introduction to this set of characters, which constitute perhaps the least principled elements of the Standard.
TrueType table listing
This is a list of the tables used in TrueType files. Also included are tables added by OpenType, Graphite, and Apple.
Glossary
A glossary of terms associated with implementing writing systems compiled by the NRSI.
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