XML file used by Windows applications to display different fonts; contains definitions of font families and includes each font family's name, weight, style, underlining, and strikethrough setting; can be used to build multilingual fonts or to provide a fallback mechanism for specific characters that are missing on the system.

COMPOSITEFONT files replace the Win32 mechanisms that were used to solve the problems of multilingual fonts, font fallback, font binding, font association, and end-user-defined characters (EUDC). Composite fonts can be accessed using the FontFamily and Typeface portions of the System.Windows.Media Windows Presentation Foundation (WPF) API. Composite font files can be created using a Windows software development IDE such as Microsoft Visual Studio. They can also be edited with a text editor since they are stored in an XML text format.