Microsoft Typography
February 2002

This document presents information that will help font developers create or support OpenType fonts for all Syriac script languages covered by the Unicode Standard. The three styles of Syriac in use today — Estrangelo, Serto and East Syriac — all use the same Syriac encoding.

This is a multi-page specification. To access specific pages, use the Contents section below, or the navigation bar at the bottom of each page.

Contents

• Introduction
• Shaping Engine
• Features
• Appendix

Introduction

Font developers will learn how to encode script features in their fonts, choose character sets, organize font information, and use existing tools to produce Syriac script fonts. Registered features of Syriac scripts are defined and illustrated, encodings are listed, and templates are included for compiling layout tables for OpenType fonts.

This document also presents information about the Syriac OpenType shaping engine of Uniscribe, an operating system component responsible for text layout.

In addition to being a primer and specification for the creation and support of Syriac script fonts, this document is intended to more broadly illustrate the OpenType Layout architecture, feature schemes, and operating system support for shaping and positioning text.

Glossary

The following terms are useful for understanding the layout features and script rules discussed in this document.

Base Glyph - Any glyph that can have a diacritic mark above or below it. Layout operations are defined in terms of a base glyph, not a base character, as a ligature may act as the base.

Character - Each character represents a Unicode character code point. For example, the 'alaph' character is U+0710. A character may have multiple forms of glyphs.

Diacritic Mark - A character that is positioned above or below a character to provide pronunciation guidance.

Glyph - A glyph represents the displayed form of one or more characters. For example, the final, initial and medial 'beth' glyphs are all forms of the 'beth' character (U+0712).

Kashida - Also known as the 'tatweel' character (U+0640). This character is used for elongation between connecting characters, and for justification.

Ligature - A combination of glyphs that join to form a single glyph. For example, the 'rish seyame' (U072a + U0308) combinations of glyphs are mandatory ligatures for Syriac. Other ligatures are optional.

Nominal form - The glyph that is represented by the Unicode character value.