X logical font description
Encyclopedia
X Window System
The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers...
. It is intended to support:
- unique, descriptive fontComputer fontA computer font is an electronic data file containing a set of glyphs, characters, or symbols such as dingbats. Although the term font first referred to a set of metal type sorts in one style and size, since the 1990s it is generally used to refer to a scalable set of digital shapes that may be...
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
Hyphen
The hyphen is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation. The hyphen should not be confused with dashes , which are longer and have different uses, or with the minus sign which is also longer...
-prefixed, X-registered fields
Field (computer science)
In computer science, data that has several parts can be divided into fields. Relational databases arrange data as sets of database records, also called rows. Each record consists of several fields; the fields of all records form the columns....
:
- FOUNDRY: Type foundryType foundryA type foundry is a company that designs or distributes typefaces. Originally, type foundries manufactured and sold metal and wood typefaces and matrices for line-casting machines like the Linotype and Monotype machines designed to be printed on letterpress printers...
- vendor or supplier of this font - FAMILY_NAME: TypefaceTypefaceIn typography, a typeface is the artistic representation or interpretation of characters; it is the way the type looks. Each type is designed and there are thousands of different typefaces in existence, with new ones being developed constantly....
family - WEIGHT_NAME: Weight of type
- SLANT: Slant (upright, italicItalic typeIn typography, italic type is a cursive typeface based on a stylized form of calligraphic handwriting. Owing to the influence from calligraphy, such typefaces often slant slightly to the right. Different glyph shapes from roman type are also usually used—another influence from calligraphy...
, obliqueOblique typeOblique type is a form of type that slants slightly to the right, used in the same manner as italic type. Unlike italic type, however, it does not use different glyph shapes; it uses the same glyphs as roman type, except distorted...
, 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. (SansSans-serifIn typography, a sans-serif, sans serif or san serif typeface is one that does not have the small projecting features called "serifs" at the end of strokes. The term comes from the French word sans, meaning "without"....
) SerifSerifIn typography, serifs are semi-structural details on the ends of some of the strokes that make up letters and symbols. A typeface with serifs is called a serif typeface . A typeface without serifs is called sans serif or sans-serif, from the French sans, meaning “without”...
, Informal, Decorated) - PIXEL_SIZE: Size of characters, in pixelPixelIn digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s; 0 (Zero0 (number)0 is both a numberand the numerical digit used to represent that number in numerals.It fulfills a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures. As a digit, 0 is used as a placeholder in place value systems...
) means a scalable font - POINT_SIZE: Size of characters, in tenths of pointsPoint (typography)In typography, a point is the smallest unit of measure, being a subdivision of the larger pica. It is commonly abbreviated as pt. The point has long been the usual unit for measuring font size and leading and other minute items on a printed page....
- RESOLUTION_X: Horizontal resolutionImage resolutionImage resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....
in dots per inchDots per inchDots per inch is a measure of spatial printing or video dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch . The DPI value tends to correlate with image resolution, but is related only indirectly.- DPI measurement in monitor...
(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 encodingCharacter encodingA character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in...
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.)