X logical font description (XLFD) is a font standard used by the X Window System and first published in 1988.Jim Flowers; Stephen Gildea (1994). "X Logical Font Description Conventions" Modern X software typically relies on the newer Fontconfig system instead, but XLFDs are still supported in current X window implementations for compatibility with legacy software.
XLFD is intended to support:
unique, descriptive font names that support simple pattern matching multiple font vendors, arbitrary character sets, and encodings naming and instancing of scalable and polymorphic fonts transformations and subsetting of fonts independence of X server and operating or file system implementations arbitrarily complex font matching or substitution extensibility
One prominent XLFD convention is to refer to individual fonts including any variations using their unique FontName. It comprises a sequence of fourteen hyphen-prefixed, X-registered fields:
FOUNDRY: Type foundry - vendor or supplier of this font FAMILY_NAME: Typeface family WEIGHT_NAME: Weight of type SLANT: Slant (upright, italic, oblique, reverse italic, reverse oblique, or "other") SETWIDTH_NAME: Proportionate width (e.g. normal, condensed, narrow, expanded/double-wide) ADD_STYLE_NAME: Additional style (e.g. (Sans) Serif, Informal, Decorated) PIXEL_SIZE: Size of characters, in pixels; 0 (Zero) means a scalable font POINT_SIZE: Size of characters, in tenths of points RESOLUTION_X: Horizontal resolution in dots per inch (DPI), for which the font was designed RESOLUTION_Y: Vertical resolution, in DPI SPACING: monospaced, proportional, or "character cell" AVERAGE_WIDTH: Average width of characters of this font, in tenths of a pixel; 0 means scalable font CHARSET_REGISTRY: Registry defining this character set CHARSET_ENCODING: Registry's character encoding scheme for this set
The following sample is for a 75-dpi, 12-point, Charter font:
-bitstream-charter-medium-r-normal--12-120-75-75-p-68-iso8859-1[65 70 80_90] (which also tells the font source that the client is interested only in characters 65, 70, and 80-90.)
References