Graphite (smart font technology)
Graphite is a programmable Unicode-compliant smart font technology and rendering system developed by SIL International as free software, distributed under the terms of the GNU Lesser General Public License and the Common Public License. == Capabilities and comparison to other smart font technologies == Graphite is based on the TrueType font format, and adds three of its own tables.
Source: Wikipedia — Graphite (smart font technology) (CC BY-SA 4.0)