1. Welcome to TrueType Open
TrueType Open is an extension to the TrueType font standard. TrueType Open fonts contain additional information that extends the capabilities of the fonts to support high-quality international typography:
TrueType Open can associate a single character with multiple glyphs, and—conversely—it can associate combinations of characters with a single glyph.
TrueType Open includes two-dimensional information to support features for complex positioning and glyph attachment.
TrueType Open contains explicit script and language information, so a text-processing application can adjust its behavior accordingly.
TrueType Open has an open format that allows font developers to define their own typographical features.
This overview introduces the power and flexibility of the TrueType Open font model. The rest of the document describes the TrueType Open components in technical detail that will be useful to font vendors and software developers creating TrueType fonts and the text-processing applications that use them.