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:

    “It is possible—indeed possible even according to the old conception of logic—to give in advance a description of all ‘true’ logical propositions. Hence there can never be surprises in logic.”
    —Ludwig Wittgenstein (1889–1951)

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

    “God damnit, why must all those journalists be such sticklers for detail? Why, they’d hold you to an accurate description of the first time you ever made love, expecting you to remember the color of the room and the shape of the windows.”
    —Lyndon Baines Johnson (1908–1973)