Beyond Glyphs, Advanced Typographic Features of Fonts
Two hundred years ago a font was a collection of small pieces of metal. Using that font required the services of a skilled typesetter to handle the niceties of kerning and ligatures. Modern fonts are expected to encapsulate both the letter shapes found on the pieces of metal, and the intelligence of the typesetter by providing information on how to position and replace glyphs as appropriate. As our view of typography extends beyond the familiar Latin, Greek and Cyrillic scripts into the more complex Arabic and Indic we need greater expressive power in the font itself. As of this writing there are two fairly common methods to include these metainformation within a font, that used by Apple (GX technology) and that used by MicroSoft and Adobe (OpenType). I shall compare these two formats and describe how FontForge, a modern open source font editor, may be used to implement either or both.