Editing OpenType (section)

==SING gaiji solution==
In 2005, Adobe shipped a new technology in their [[Adobe Creative Suite|Creative Suite]] applications bundle that offers a solution for "[[gaiji]]" (外字, Japanese for "outside character"). Ideographic writing scripts such as Chinese and Japanese do not have fixed collections of characters. They use thousands of glyphs commonly and tens of thousands less commonly. Not all glyphs ever invented and used in East Asian literature have even been catalogued. A typical font might contain 8,000 to 15,000 of the most commonly used glyphs. From time to time, though, an author needs a glyph not present in the font of choice. Such missing characters are known in Japan as gaiji, and they often disrupt work.

Another aspect of the gaiji problem is that of variant glyphs for certain characters. Often certain characters have been written differently over periods of time. It is not unusual for place names or personal family names to use a historical form of a character. Thus it is possible for an [[End-user (computer science)|end user]] using standard fonts to be left unable to spell correctly either their own name or the name of the place where they live.

Several ways to deal with gaiji have been devised. Solutions that treat them as characters usually assign arbitrary Unicode values to them in the [[Private Use Areas]] (PUA). Such characters cannot be used outside the environment in which the association of the private Unicode to the glyph shape is known. Documents based on them are not portable. Other installations treat gaiji as graphics. This can be cumbersome because text layout and composition cannot apply to graphics. They cannot be searched for. Often their rendering looks different from surrounding characters because the machinery for rendering graphics usually is different from the machinery for rendering glyphs from fonts.

The SING (Smart INdependent Glyphlets)<ref>{{cite web|url=https://www.adobe.com/devnet/opentype/gdk/topic.html |title=Adobe Glyphlet Development Kit (GDK) for SING Gaiji Architecture |publisher=Adobe.com |access-date=2009-11-11 |archive-url = https://web.archive.org/web/20080627183635/http://www.adobe.com/devnet/opentype/gdk/topic.html |archive-date = June 27, 2008}}</ref><ref>{{cite conference|last=DeLaHunt |first=Jim |url=http://partners.adobe.com/public/developer/en/opentype/SING_Intro_IUC26.pdf |title=SING: Adobe's New Gaiji Architecture |archive-url=https://web.archive.org/web/20150123212327/http://partners.adobe.com/public/developer/en/opentype/SING_Intro_IUC26.pdf |archive-date=2015-01-23 |date=September 2004 |access-date=16 July 2009| conference=26th Internationalization and Unicode Conference}}</ref> technology that made its debut with Adobe's Creative Suite 2 allows for the creation of glyphs, each packaged as a standalone font, after a fashion. Such a packaged glyph is called a ''glyphlet''. The format, which Adobe has made public, is based on OpenType. The package consists of the glyph outline in TrueType or [[CFF fonts|CFF]] (PostScript style outlines) form; standard OpenType tables declaring the glyph's metrics and behavior in composition; and metadata, extra information included for identifying the glyphlet, its ownership, and perhaps pronunciation or linguistic categorization. SING glyphlets can be created using [[Fontlab]]'s SigMaker3 application.

The SING specification states that glyphlets are to [[font embedding|travel with the document]] they are used in. That way documents are portable, leaving no danger of characters in the document that cannot be displayed. Because glyphlets are essentially OpenType fonts, standard font machinery can render them. The SING specification also describes an [[XML]] format that includes all the data necessary for reconstituting the glyphlet in binary form. A typical glyphlet might require one to two kilobytes to represent.