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)

    “Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.”
    —Paul Tillich (1886–1965)