title: X logical font description
text: # X logical font description
  
  X logical font description (XLFD) is a font standard used by the X Window System. 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; 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:
  
  (which also tells the font source that the client is interested only in characters 65, 70, and 80-90.)
  
  