X Logical Font Description

X logical font description (XLFD) is a font standard used by the X Window System. It 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:

  1. FOUNDRY: Type foundry - vendor or supplier of this font
  2. FAMILY_NAME: Typeface family
  3. WEIGHT_NAME: Weight of type
  4. SLANT: Slant (upright, italic, oblique, reverse italic, reverse oblique, or "other")
  5. SETWIDTH_NAME: Proportionate width (e.g. normal, condensed, narrow, expanded/double-wide)
  6. ADD_STYLE_NAME: Additional style (e.g. (Sans) Serif, Informal, Decorated)
  7. PIXEL_SIZE: Size of characters, in pixels; 0 (Zero) means a scalable font
  8. POINT_SIZE: Size of characters, in tenths of points
  9. RESOLUTION_X: Horizontal resolution in dots per inch (DPI), for which the font was designed
  10. RESOLUTION_Y: Vertical resolution, in DPI
  11. SPACING: monospaced, proportional, or "character cell"
  12. AVERAGE_WIDTH: Average width of characters of this font; 0 means scalable font
  13. CHARSET_REGISTRY: Registry defining this character set
  14. 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

(which also tells the font source that the client is interested only in characters 65, 70, and 80-90.)

Famous quotes containing the words logical, font and/or description:

    “A picture whose pictorial form is logical form is called a logical picture.”
    —Ludwig Wittgenstein (1889–1951)

    “Le corps, l’amour, la mort, ces trois ne font qu’un.”
    —Thomas Mann (1875–1955)

    “The next Augustan age will dawn on the other side of the Atlantic. There will, perhaps, be a Thucydides at Boston, a Xenophon at New York, and, in time, a Virgil at Mexico, and a Newton at Peru. At last, some curious traveller from Lima will visit England and give a description of the ruins of St Paul’s, like the editions of Balbec and Palmyra.”
    —Horace Walpole (1717–1797)