File used by LaTeX, a typesetting system used to create formatted documents; contains a font declaration that maps LaTeX font properties to TeX font specifications; used to describe how LaTeX font attributes are translated into TeX fonts. FD files are stored in a plain text format and contain commands that declare font families, font provider files, and font encodings.
Data file used by DataFlex, a 4GL (Fourth-Generation Programming Language) used for creating business database applications; contains references to an internal DataFlex number as well as DataFlex column definitions. FD files are used by the DataFlex compiler to associate program code references with database tables.