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X Logical Font Description Conventions Version 1.5 X Consortium Standard X Version 11, Release 6.4 Jim Flowers Digital Equipment Corporation Version 1.5 edited by Stephen Gildea X Consortium, Inc. X Window System is a trademark of X Consortium, Inc. Helvetica and Times are registered trademarks of Linotype Company. ITC Avant Garde Gothic is a registered trademark of International Type- face Corporation. Times Roman is a registered trademark of Monotype Corporation. Bitstream Amerigo is a registered trademark of Bitstream Inc. Stone is a registered trademark of Adobe Systems Inc. Copyright (C) 1988, 1994 X Consortium Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Soft- ware"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following condi- tions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL- ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABIL- ITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Except as contained in this notice, the name of the X Consortium shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the X Consortium. Copyright (C) 1988, 1989 Digital Equipment Corporation, Maynard MA. All rights reserved. Permission to use, copy, modify, and distribute this documentation for any purpose and without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. Digi- tal Equipment Corporation makes no representations about the suitability for any purpose of the information in this document. This documentation is provided as is without express or implied warranty. 1. Introduction It is a requirement that X client applications must be portable across server implementations, with very different file systems, naming conven- tions, and font libraries. However, font access requests, as defined by the X Window System Protocol, neither specify server-independent conven- tions for font names nor provide adequate font properties for logically describing typographic fonts. X clients must be able to dynamically determine the fonts available on any given server so that understandable information can be presented to the user or so that intelligent font fallbacks can be chosen. It is desirable for the most common queries to be accomplished without the overhead of opening each font and inspecting font properties, by means of simple ListFonts requests. For example, if a user selected a Hel- vetica typeface family, a client application should be able to query the server for all Helvetica fonts and present only those setwidths, weights, slants, point sizes, and character sets available for that fam- ily. This document gives a standard logical font description (hereafter referred to as XLFD) and the conventions to be used in the core protocol so that clients can query and access screen type libraries in a consis- tent manner across all X servers. In addition to completely specifying a given font by means of its FontName, the XLFD also provides for a standard set of key FontProperties that describe the font in more detail. The XLFD provides an adequate set of typographic font properties, such as CAP_HEIGHT, X_HEIGHT, and RELATIVE_SETWIDTH, for publishing and other applications to do intelligent font matching or substitution when han- dling documents created on some foreign server that use potentially unknown fonts. In addition, this information is required by certain clients to position subscripts automatically and determine small capital heights, recommended leading, word-space values, and so on. 2. Requirements and Goals The XLFD meets the short-term and long-term goals to have a standard logical font description that: o Provides unique, descriptive font names that support simple pattern matching o Supports multiple font vendors, arbitrary character sets, and encodings o Supports naming and instancing of scalable and polymorphic fonts o Supports transformations and subsetting of fonts o Is independent of X server and operating or file system implementa- tions 1 X Logical Font Description Conventions X11, Release 6.4 o Supports arbitrarily complex font matching or substitution o Is extensible 2.1. Provide Unique and Descriptive Font Names It should be possible to have font names that are long enough and descriptive enough to have a reasonable probability of being unique without inventing a new registration organization. Resolution and size- dependent font masters, multivendor font libraries, and so on must be anticipated and handled by the font name alone. The name itself should be structured to be amenable to simple pattern matching and parsing, thus allowing X clients to restrict font queries to some subset of all possible fonts in the server. 2.2. Support Multiple Font Vendors and Character Sets The font name and properties should distinguish between fonts that were supplied by different font vendors but that possibly share the same name. We anticipate a highly competitive font market where users will be able to buy fonts from many sources according to their particular requirements. A number of font vendors deliver each font with all glyphs designed for that font, where charset mappings are defined by encoding vectors. Some server implementations may force these mappings to proprietary or stan- dard charsets statically in the font data. Others may desire to perform the mapping dynamically in the server. Provisions must be made in the font name that allows a font request to specify or identify specific charset mappings in server environments where multiple charsets are sup- ported. 2.3. Support Scalable and Polymorphic Fonts If a font source can be scaled to an arbitrary size or varied in other ways, it should be possible for an application to determine that fact from the font name, and the application should be able to construct a font name for any specific instance. 2.4. Support Transformations and Subsetting of Fonts Arbitrary two-dimensional linear transformations of fonts should be able to be requested by applications. Since such transformed fonts may be used for special effects requiring a few characters from each of many differently transformed fonts, it should be possible to request only a few characters from a font for efficiency. 2.5. Be Independent of X Server and Operating or File System Implemen- tations X client applications that require a particular font should be able to use the descriptive name without knowledge of the file system or other repository in use by the server. However, it should be possible for 2 X Logical Font Description Conventions X11, Release 6.4 servers to translate a given font name into a file name syntax that it knows how to deal with, without compromising the uniqueness of the font name. This algorithm should be reversible (exactly how this translation is done is implementation dependent). 2.6. Support Arbitrarily Complex Font Matching and Substitution In addition to the font name, the XLFD should define a standard list of descriptive font properties, with agreed-upon fallbacks for all fonts. This allows client applications to derive font-specific formatting or display data and to perform font matching or substitution when asked to handle potentially unknown fonts, as required. 2.7. Be Extensible The XLFD must be extensible so that new and/or private descriptive font properties can be added to conforming fonts without making existing X client or server implementations obsolete. 3. X Logical Font Description XLFD is divided into two basic components: the FontName, which gives all font information needed to uniquely identify a font in X protocol requests (for example, OpenFont, ListFonts, and so on) and a variable list of optional FontProperties, which describe a font in more detail. The FontName is used in font queries and is returned as data in certain X protocol requests. It is also specified as the data value for the FONT item in the X Consortium Character Bitmap Distribution Format Stan- dard (BDF V2.1). The FontProperties are supplied on a font-by-font basis and are returned as data in certain X protocol requests as part of the XFontStruct data structure. The names and associated data values for each of the Font- Properties may also appear as items of the STARTPROPERTIES...ENDPROPER- TIES list in the BDF V2.1 specification. 3.1. FontName Each FontName is logically composed of two strings: a FontNameRegistry prefix that is followed by a FontNameSuffix. The FontName uses the ISO 8859-1 encoding. The FontNameRegistry is an x-registered-name (a name that has been registered with the X Consortium) that identifies the reg- istration authority that owns the specified FontNameSuffix syntax and semantics. All font names that conform to this specification are to use a Font- NameRegistry prefix, which is defined to be the string "-" (HYPHEN). All FontNameRegistry prefixes of the form: +version-, where the speci- fied version indicates some future XLFD specification, are reserved by the X Consortium for future extensions to XLFD font names. If required, extensions to the current XLFD font name shall be constructed by append- ing new fields to the current structure, each delimited by the existing field delimiter. The availability of other FontNameRegistry prefixes or 3 X Logical Font Description Conventions X11, Release 6.4 fonts that support other registries is server implementation dependent. In the X protocol specification, the FontName is required to be a string; hence, numeric field values are represented in the name as string equivalents. All FontNameSuffix fields are also defined as FontProperties; numeric property values are represented as signed or unsigned integers, as appropriate. 3.1.1. FontName Syntax The FontName is a structured, parsable string (of type STRING8) whose Backus-Naur Form syntax description is as follows: FontName ::= XFontNameRegistry XFontNameSuffix | PrivFontNameRegistry PrivFontNameSuf- fix XFontNameRegistry ::= XFNDelim | XFNExtPrefix Version XFN- Delim XFontNameSuffix ::= FOUNDRY XFNDelim FAMILY_NAME XFNDelim WEIGHT_NAME XFNDelim SLANT XFNDelim SETWIDTH_NAME XFNDelim ADD_ STYLE_NAME XFNDelim PIXEL_SIZE XFNDe- lim POINT_SIZE XFNDelim RESOLUTION_X XFNDelim RESOLUTION_Y XFNDelim SPAC- ING XFNDelim AVERAGE_WIDTH XFNDelim CHARSET_REGISTRY XFNDelim CHARSET_ENCODING Version ::= STRING8 - the XLFD version that defines an extension to the font name syntax (for example, "1.4") XFNExtPrefix ::= OCTET - "+" (PLUS) XFNDelim ::= OCTET - "-" (HYPHEN) PrivFontNameRegistry STRING8 - other than those strings ::= reserved by XLFD PrivFontNameSuffix ::= STRING8 Field values are constructed as strings of ISO 8859-1 graphic charac- ters, excluding the following: o "-" (HYPHEN), the XLFD font name delimiter character o "?" (QUESTION MARK) and "*" (ASTERISK), the X protocol font name wildcard characters o "," (COMMA), used by Xlib to separate XLFD font names in a font set. o """ (QUOTATION MARK), used by some commercial products to quote a font name. Alphabetic case distinctions are allowed but are for human readability concerns only. Conforming X servers will perform matching on font name query or open requests independent of case. The entire font name string 4 X Logical Font Description Conventions X11, Release 6.4 must have no more than 255 characters. It is recommended that clients construct font name query patterns by explicitly including all field delimiters to avoid unexpected results. Note that SPACE is a valid character of a FontName field; for example, the string "ITC Avant Garde Gothic" might be a FAMILY_NAME. 3.1.2. FontName Field Definitions This section discusses the FontName: o FOUNDRY field o FAMILY_NAME field o WEIGHT_NAME field o SLANT field o SETWIDTH_NAME field o ADD_STYLE_NAME field o PIXEL_SIZE field o POINT_SIZE field o RESOLUTION_X and RESOLUTION_Y fields o SPACING field o AVERAGE_WIDTH field o CHARSET_REGISTRY and CHARSET_ENCODING fields 3.1.2.1. FOUNDRY Field FOUNDRY is an x-registered-name, the name or identifier of the digital type foundry that digitized and supplied the font data, or if different, the identifier of the organization that last modified the font shape or metric information. The reason this distinction is necessary is that a given font design may be licensed from one source (for example, ITC) but digitized and sold by any number of different type suppliers. Each digital version of the original design, in general, will be somewhat different in metrics and shape from the idealized original font data, because each font foundry, for better or for worse, has its own standards and practices for tweak- ing a typeface for a particular generation of output technologies or has its own perception of market needs. It is up to the type supplier to register with the X Consortium a suit- able name for this FontName field according to the registration proce- dures defined by the Consortium. 5 X Logical Font Description Conventions X11, Release 6.4 The X Consortium shall define procedures for registering foundry and other names and shall maintain and publish, as part of its public dis- tribution, a registry of such registered names for use in XLFD font names and properties. 3.1.2.2. FAMILY_NAME Field FAMILY_NAME is a string that identifies the range or family of typeface designs that are all variations of one basic typographic style. This must be spelled out in full, with words separated by spaces, as required. This name must be human-understandable and suitable for pre- sentation to a font user to identify the typeface family. It is up to the type supplier to supply and maintain a suitable string for this field and font property, to secure the proper legal title to a given name, and to guard against the infringement of other's copyrights or trademarks. By convention, FAMILY_NAME is not translated. FAM- ILY_NAME may include an indication of design ownership if considered a valid part of the typeface family name. The following are examples of FAMILY_NAME: o Helvetica o ITC Avant Garde Gothic o Times o Times Roman o Bitstream Amerigo o Stone 3.1.2.3. WEIGHT_NAME Field WEIGHT_NAME is a string that identifies the font's typographic weight, that is, the nominal blackness of the font, according to the FOUNDRY's judgment. This name must be human-understandable and suitable for pre- sentation to a font user. The value "0" is used to indicate a polymor- phic font (see section 6). The interpretation of this field is somewhat problematic because the typographic judgment of weight has traditionally depended on the overall design of the typeface family in question; that is, it is possible that the DemiBold weight of one font could be almost equivalent in typo- graphic feel to a Bold font from another family. WEIGHT_NAME is captured as an arbitrary string because it is an impor- tant part of a font's complete human-understandable name. However, it should not be used for font matching or substitution. For this purpose, X client applications should use the weight-related font properties (RELATIVE_WEIGHT and WEIGHT) that give the coded relative weight and the 6 X Logical Font Description Conventions X11, Release 6.4 calculated weight, respectively. 3.1.2.4. SLANT Field SLANT is a code-string that indicates the overall posture of the type- face design used in the font. The encoding is as follows: --------------------------------------------------------------------------- Code English Translation Description --------------------------------------------------------------------------- "R" Roman Upright design "I" Italic Italic design, slanted clockwise from the vertical "O" Oblique Obliqued upright design, slanted clockwise from the vertical "RI" Reverse Italic Italic design, slanted counterclockwise from the vertical "RO" Reverse Oblique Obliqued upright design, slanted counter- clockwise from the vertical "OT" Other Other numeric Polymorphic See section 6 on polymorphic font support. --------------------------------------------------------------------------- The SLANT codes are for programming convenience only and usually are converted into their equivalent human-understandable form before being presented to a user. 3.1.2.5. SETWIDTH_NAME Field SETWIDTH_NAME is a string that gives the font's typographic proportion- ate width, that is, the nominal width per horizontal unit of the font, according to the FOUNDRY's judgment. The value "0" is used to indicate a polymorphic font (see section 6). As with WEIGHT_NAME, the interpretation of this field or font property is somewhat problematic, because the designer's judgment of setwidth has traditionally depended on the overall design of the typeface family in question. For purposes of font matching or substitution, X client applications should either use the RELATIVE_SETWIDTH font property that gives the relative coded proportionate width or calculate the propor- tionate width. The following are examples of SETWIDTH_NAME: o Normal o Condensed o Narrow o Double Wide 7 X Logical Font Description Conventions X11, Release 6.4 3.1.2.6. ADD_STYLE_NAME Field ADD_STYLE_NAME is a string that identifies additional typographic style information that is not captured by other fields but is needed to iden- tify the particular font. The character "[" anywhere in the field is used to indicate a polymorphic font (see section 6). ADD_STYLE_NAME is not a typeface classification field and is only used for uniqueness. Its use, as such, is not limited to typographic style distinctions. The following are examples of ADD_STYLE_NAME: o Serif o Sans Serif o Informal o Decorated 3.1.2.7. PIXEL_SIZE Field PIXEL_SIZE gives the body size of the font at a particular POINT_SIZE and RESOLUTION_Y. PIXEL_SIZE is either an integer-string or a string beginning with "[". A string beginning with "[" represents a matrix (see section 4). PIXEL_SIZE usually incorporates additional vertical spacing that is considered part of the font design. (Note, however, that this value is not necessarily equivalent to the height of the font bounding box.) Zero is used to indicate a scalable font (see section 5). PIXEL_SIZE usually is used by X client applications that need to query fonts according to device-dependent size, regardless of the point size or vertical resolution for which the font was designed. 3.1.2.8. POINT_SIZE Field POINT_SIZE gives the body size for which the font was designed. POINT_SIZE is either an integer-string or a string beginning with "[". A string beginning with "[" represents a matrix (see section 4). This field usually incorporates additional vertical spacing that is consid- ered part of the font design. (Note, however, that POINT_SIZE is not necessarily equivalent to the height of the font bounding box.) POINT_SIZE is expressed in decipoints (where points are as defined in the X protocol or 72.27 points equal 1 inch). Zero is used to indicate a scalable font (see section 5). POINT_SIZE and RESOLUTION_Y are used by X clients to query fonts accord- ing to device-independent size to maintain constant text size on the display regardless of the PIXEL_SIZE used for the font. 8 X Logical Font Description Conventions X11, Release 6.4 3.1.2.9. RESOLUTION_X and RESOLUTION_Y Fields RESOLUTION_X and RESOLUTION_Y are unsigned integer-strings that give the horizontal and vertical resolution, measured in pixels or dots per inch (dpi), for which the font was designed. Zero is used to indicate a scalable font (see section 5). Horizontal and vertical values are required because a separate bitmap font must be designed for displays with very different aspect ratios (for example, 1:1, 4:3, 2:1, and so on). The separation of pixel or point size and resolution is necessary because X allows for servers with very different video characteristics (for example, horizontal and vertical resolution, screen and pixel size, pixel shape, and so on) to potentially access the same font library. The font name, for example, must differentiate between a 14-point font designed for 75 dpi (body size of about 14 pixels) or a 14-point font designed for 150 dpi (body size of about 28 pixels). Further, in servers that implement some or all fonts as continuously scaled and scan-converted outlines, POINT_SIZE and RESOLUTION_Y will help the server to differentiate between potentially separate font masters for text, title, and display sizes or for other typographic considerations. 3.1.2.10. SPACING Field SPACING is a code-string that indicates the escapement class of the font, that is, monospace (fixed pitch), proportional (variable pitch), or charcell (a special monospaced font that conforms to the traditional data-processing character cell font model). The encoding is as follows: ------------------------------------------------------------------ Code English Translation Description ------------------------------------------------------------------ "P" Proportional A font whose logical character widths vary for each glyph. Note that no other restrictions are placed on the metrics of a propor- tional font. "M" Monospaced A font whose logical character widths are constant (that is, every glyph in the font has the same log- ical width). No other restrictions are placed on the metrics of a monospaced font. 9 X Logical Font Description Conventions X11, Release 6.4 ------------------------------------------------------------------ Code English Translation Description ------------------------------------------------------------------ "C" CharCell A monospaced font that follows the standard typewriter character cell model (that is, the glyphs of the font can be modeled by X clients as "boxes" of the same width and height that are imaged side-by-side to form text strings or top-to-bot- tom to form text lines). By defi- nition, all glyphs have the same logical character width, and no glyphs have "ink" outside of the character cell. There is no kern- ing (that is, on a per-character basis with positive metrics: 0 <= left-bearing <= right-bearing <= width; with negative metrics: width <= left-bearing <= right-bearing <= zero). Also, the vertical extents of the font do not exceed the ver- tical spacing (that is, on a per- character basis: ascent <= font- ascent and descent <= font- descent). The cell height = font- descent + font-ascent, and the width = AVERAGE_WIDTH. ------------------------------------------------------------------ 3.1.2.11. AVERAGE_WIDTH Field AVERAGE_WIDTH is an integer-string typographic metric value that gives the unweighted arithmetic mean of the absolute value of the width of each glyph in the font (measured in tenths of pixels), multiplied by -1 if the dominant writing direction for the font is right-to-left. A leading "~" (TILDE) indicates a negative value. For monospaced and character cell fonts, this is the width of all glyphs in the font. Zero is used to indicate a scalable font (see section 5). 3.1.2.12. CHARSET_REGISTRY and CHARSET_ENCODING Fields The character set used to encode the glyphs of the font (and implicitly the font's glyph repertoire), as maintained by the X Consortium charac- ter set registry. CHARSET_REGISTRY is an x-registered-name that identi- fies the registration authority that owns the specified encoding. CHARSET_ENCODING is a registered name that identifies the coded charac- ter set as defined by that registration authority and, optionally, a subsetting hint. Although the X protocol does not explicitly have any knowledge about character set encodings, it is expected that server implementors will prefer to embed knowledge of certain proprietary or standard charsets 10 X Logical Font Description Conventions X11, Release 6.4 into their font library for reasons of performance and convenience. The CHARSET_REGISTRY and CHARSET_ENCODING fields or properties allow an X client font request to specify a specific charset mapping in server environments where multiple charsets are supported. The availability of any particular character set is font and server implementation depen- dent. To prevent collisions when defining character set names, it is recom- mended that CHARSET_REGISTRY and CHARSET_ENCODING name pairs be con- structed according to the following conventions: CharsetRegistry ::= StdCharsetRegistryName | PrivCharsetReg- istryName CharsetEncoding ::= StdCharsetEncodingName | PrivCharsetEn- codingName StdCharsetRegistryName ::= StdOrganizationId StdNumber | StdOrgani- zationId StdNumber Dot Year PrivCharsetRegistryName ::= OrganizationId STRING8 StdCharsetEncodingName ::= STRING8-numeric part number of refer- enced standard PrivCharsetEncodingName ::= STRING8 StdOrganizationId ::= STRING8-the registered name or acronym of the referenced standard organization StdNumber ::= STRING8-referenced standard number OrganizationId ::= STRING8-the registered name or acronym of the organization Dot ::= OCTET-"." (FULL STOP) Year ::= STRING8-numeric year (for example, 1989) The X Consortium shall maintain and publish a registry of such character set names for use in X protocol font names and properties as specified in XLFD. The ISO Latin-1 character set shall be registered by the X Consortium as the CHARSET_REGISTRY-CHARSET_ENCODING value pair: "ISO8859-1". If the CHARSET_ENCODING contains a "[" (LEFT SQUARE BRACKET), the "[" and the characters after it up to a "]" (RIGHT SQUARE BRACKET) are a subsetting hint telling the font source that the client is interested only in a subset of the characters of the font. The font source can, optionally, return a font that contains only those characters or any superset of those characters. The client can expect to obtain valid glyphs and metrics only for those characters, and not for any other characters in the font. The font properties may optionally be calcu- lated by considering only the characters in the subset. The BNF for the subsetting hint is Subset ::= LeftBracket RangeList RightBracket RangeList ::= Range | Range Space RangeList Range ::= Number | Number Underscore Number Number ::= "0x" HexNumber | DecNumber 11 X Logical Font Description Conventions X11, Release 6.4 HexNumber ::= HexDigit | HexDigit HexNumber DecNumber ::= DecDigit | DecDigit DecNumber DecDigit ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" HexDigit ::= DecDigit | "a" | "b" | "c" | "d" | "e" | "f" LeftBracket ::= "[" (LEFT SQUARE BRACKET) RightBracket ::= "]" (RIGHT SQUARE BRACKET) Space ::= " " (SPACE) Underscore ::= "_" (LOW LINE) Each Range specifies characters that are to be part of the subset included in the font. A Range containing two Numbers specifies the first and last character, inclusively, of a range of characters. A Range that is a single Number specifies a single character to be included in the font. A HexNumber is interpreted as a hexadecimal num- ber. A DecNumber is interpreted as a decimal number. The font consists of the union of all the Ranges in the RangeList. For example, -misc-fixed-medium-r-normal--0-0-0-0-c-0-iso8859-1[65 70 80_90] tells the font source that the client is interested only in characters 65, 70, and 80-90. 3.1.3. Examples The following examples of font names are derived from the screen fonts shipped with the X Consortium distribution. ------------------------------------------------------------------------------ Font X FontName ------------------------------------------------------------------------------ 75-dpi Fonts Charter 12 pt -Bitstream-Charter-Medium-R-Nor- mal--12-120-75-75-P-68-ISO8859-1 Charter Bold -Bitstream-Charter-Bold-R-Nor- 12 pt mal--12-120-75-75-P-76-ISO8859-1 Charter Bold -Bitstream-Charter-Bold-I-Nor- Italic 12 pt mal--12-120-75-75-P-75-ISO8859-1 Charter Italic -Bitstream-Charter-Medium-I-Nor- 12 pt mal--12-120-75-75-P-66-ISO8859-1 Courier 8 pt -Adobe-Courier-Medium-R-Normal--8-80-75-75-M-50-ISO8859-1 Courier 10 pt -Adobe-Courier-Medium-R-Normal--10-100-75-75-M-60-ISO8859-1 Courier 12 pt -Adobe-Courier-Medium-R-Normal--12-120-75-75-M-70-ISO8859-1 Courier 24 pt -Adobe-Courier-Medium-R-Normal--24-240-75-75-M-150-ISO8859-1 Courier Bold -Adobe-Courier-Bold-R-Normal--10-100-75-75-M-60-ISO8859-1 10 pt Courier Bold -Adobe-Courier-Bold-O-Normal--10-100-75-75-M-60-ISO8859-1 Oblique 10 pt Courier -Adobe-Courier-Medium-O-Normal--10-100-75-75-M-60-ISO8859-1 Oblique 10 pt 100-dpi Fonts Symbol 10 pt -Adobe-Symbol-Medium-R-Normal--14-100-100-100-P-85-Adobe- FONTSPECIFIC 12 X Logical Font Description Conventions X11, Release 6.4 ------------------------------------------------------------------------------ Font X FontName ------------------------------------------------------------------------------ Symbol 14 pt -Adobe-Symbol-Medium-R-Normal--20-140-100-100-P-107-Adobe- FONTSPECIFIC Symbol 18 pt -Adobe-Symbol-Medium-R-Normal--25-180-100-100-P-142-Adobe- FONTSPECIFIC Symbol 24 pt -Adobe-Symbol-Medium-R-Normal--34-240-100-100-P-191-Adobe- FONTSPECIFIC Times Bold 10 -Adobe-Times-Bold-R-Normal--14-100-100-100-P-76-ISO8859-1 pt Times Bold -Adobe-Times-Bold-I-Normal--14-100-100-100-P-77-ISO8859-1 Italic 10 pt Times Italic -Adobe-Times-Medium-I-Normal--14-100-100-100-P-73-ISO8859-1 10 pt Times Roman 10 -Adobe-Times-Medium-R-Normal--14-100-100-100-P-74-ISO8859-1 pt ------------------------------------------------------------------------------ 3.2. Font Properties All font properties are optional but will generally include the font name fields and, on a font-by-font basis, any other useful font descrip- tive and use information that may be required to use the font intelli- gently. The XLFD specifies an extensive set of standard X font proper- ties, their interpretation, and fallback rules when the property is not defined for a given font. The goal is to provide client applications with enough font information to be able to make automatic formatting and display decisions with good typographic results. Font property names use the ISO 8859-1 encoding. Additional standard X font property definitions may be defined in the future and private properties may exist in X fonts at any time. Private font properties should be defined to conform to the general mechanism defined in the X protocol to prevent overlap of name space and ambiguous property names, that is, private font property names are of the form: "_" (LOW LINE), followed by the organizational identifier, followed by "_" (LOW LINE), and terminated with the property name. The Backus-Naur Form syntax description of X font properties is as fol- lows: Properties ::= OptFontPropList OptFontPropList ::= NULL | OptFontProp OptFontPropList OptFontProp ::= PrivateFontProp | XFontProp PrivateFontProp ::= STRING8 | Underscore OrganizationId Underscore STRING8 13 X Logical Font Description Conventions X11, Release 6.4 XFontProp ::= FOUNDRY | FAMILY_NAME | WEIGHT_NAME | SLANT | SETWIDTH_NAME | ADD_STYLE_NAME | PIXEL_SIZE | POINT_SIZE | RESOLUTION_X | RESOLU- TION_Y | SPACING | AVERAGE_WIDTH | CHARSET_REGISTRY | CHARSET_ENCODING | QUAD_WIDTH | RESOLUTION | MIN_SPACE | NORM_SPACE | MAX_SPACE | END_SPACE | SUPERSCRIPT_X | SUPERSCRIPT_Y | SUB- SCRIPT_X | SUBSCRIPT_Y | UNDER- LINE_POSITION | UNDERLINE_THICKNESS | STRIKEOUT_ASCENT | STRIKEOUT_DESCENT | ITALIC_ANGLE | X_HEIGHT | WEIGHT | FACE_NAME | FULL_NAME | FONT | COPY- RIGHT | AVG_CAPITAL_WIDTH | AVG_LOW- ERCASE_WIDTH | RELATIVE_SETWIDTH | RELATIVE_WEIGHT | CAP_HEIGHT | SUPER- SCRIPT_ SIZE | FIGURE_WIDTH | SUB- SCRIPT_SIZE | SMALL_CAP_SIZE | NOTICE | DESTINATION | FONT_TYPE | FONT_VER- SION | RASTERIZER_NAME | RASTER- IZER_VERSION | RAW_ASCENT | RAW_DESCENT | RAW_* | AXIS_NAMES | AXIS_LIMITS | AXIS_TYPES Underscore ::= OCTET-"_" (LOW LINE) OrganizationId ::= STRING8-the registered name of the organization 3.2.1. FOUNDRY FOUNDRY is as defined in the FontName except that the property type is ATOM. FOUNDRY cannot be calculated or defaulted if not supplied as a font property. 3.2.2. FAMILY_NAME FAMILY_NAME is as defined in the FontName except that the property type is ATOM. FAMILY_NAME cannot be calculated or defaulted if not supplied as a font property. 3.2.3. WEIGHT_NAME WEIGHT_NAME is as defined in the FontName except that the property type is ATOM. WEIGHT_NAME can be defaulted if not supplied as a font property, as fol- lows: 14 X Logical Font Description Conventions X11, Release 6.4 if (WEIGHT_NAME undefined) then WEIGHT_NAME = ATOM("Medium") 3.2.4. SLANT SLANT is as defined in the FontName except that the property type is ATOM. SLANT can be defaulted if not supplied as a font property, as follows: if (SLANT undefined) then SLANT = ATOM("R") 3.2.5. SETWIDTH_NAME SETWIDTH_NAME is as defined in the FontName except that the property type is ATOM. SETWIDTH_NAME can be defaulted if not supplied as a font property, as follows: if (SETWIDTH_NAME undefined) then SETWIDTH_NAME = ATOM("Normal") 3.2.6. ADD_STYLE_NAME ADD_STYLE_NAME is as defined in the FontName except that the property type is ATOM. ADD_STYLE_NAME can be defaulted if not supplied as a font property, as follows: if (ADD_STYLE_NAME undefined) then ADD_STYLE_NAME = ATOM("") 3.2.7. PIXEL_SIZE PIXEL_SIZE is as defined in the FontName except that the property type is INT32. X clients requiring pixel values for the various typographic fixed spaces (em space, en space, and thin space) can use the following algo- rithm for computing these values from other properties specified for a font: 15 X Logical Font Description Conventions X11, Release 6.4 DeciPointsPerInch = 722.7 EMspace = ROUND ((RESOLUTION_X * POINT_SIZE) / DeciPointsPerInch) ENspace = ROUND (EMspace / 2) THINspace = ROUND (EMspace / 3) where a slash (/) denotes real division, an asterisk (*) denotes real multiplication, and ROUND denotes a function that rounds its real argu- ment a up or down to the next integer. This rounding is done according to X = FLOOR (a + 0.5), where FLOOR is a function that rounds its real argument down to the nearest integer. PIXEL_SIZE can be approximated if not supplied as a font property, according to the following algorithm: DeciPointsPerInch = 722.7 if (PIXEL_SIZE undefined) then PIXEL_SIZE = ROUND ((RESOLUTION_Y * POINT_SIZE) / DeciPointsPerInch) 3.2.8. POINT_SIZE POINT_SIZE is as defined in the FontName except that the property type is INT32. X clients requiring device-independent values for em space, en space, and thin space can use the following algorithm: EMspace = ROUND (POINT_SIZE / 10) ENspace = ROUND (POINT_SIZE / 20) THINspace = ROUND (POINT_SIZE / 30) Design POINT_SIZE cannot be calculated or approximated. 3.2.9. RESOLUTION_X RESOLUTION_X is as defined in the FontName except that the property type is CARD32. RESOLUTION_X cannot be calculated or approximated. 3.2.10. RESOLUTION_Y RESOLUTION_Y is as defined in the FontName except that the property type is CARD32. RESOLUTION_X cannot be calculated or approximated. 16 X Logical Font Description Conventions X11, Release 6.4 3.2.11. SPACING SPACING is as defined in the FontName except that the property type is ATOM. SPACING can be calculated if not supplied as a font property, according to the definitions given above for the FontName. 3.2.12. AVERAGE_WIDTH AVERAGE_WIDTH is as defined in the FontName except that the property type is INT32. AVERAGE_WIDTH can be calculated if not provided as a font property, according to the following algorithm: if (AVERAGE_WIDTH undefined) then AVERAGE_WIDTH = ROUND (MEAN (ABS (width of each glyph in font)) * 10) * (if (dominant writing direction L-to-R) then 1 else -1) where MEAN is a function that returns the arithmetic mean of its argu- ments. X clients that require values for the number of characters per inch (pitch) of a monospaced font can use the following algorithm using the AVERAGE_WIDTH and RESOLUTION_X font properties: if (SPACING not proportional) then CharPitch = (RESOLUTION_X * 10) / AVERAGE_WIDTH 3.2.13. CHARSET_REGISTRY CHARSET_REGISTRY is as defined in the FontName except that the property type is ATOM. CHARSET_REGISTRY cannot be defaulted if not supplied as a font property. 3.2.14. CHARSET_ENCODING CHARSET_ENCODING is as defined in the FontName except that the property type is ATOM. CHARSET_ENCODING cannot be defaulted if not supplied as a font property. 3.2.15. MIN_SPACE MIN_SPACE is an integer value (of type INT32) that gives the recommended minimum word-space value to be used with this font. 17 X Logical Font Description Conventions X11, Release 6.4 MIN_SPACE can be approximated if not provided as a font property, according to the following algorithm: if (MIN_SPACE undefined) then MIN_SPACE = ROUND(0.75 * NORM_SPACE) 3.2.16. NORM_SPACE NORM_SPACE is an integer value (of type INT32) that gives the recom- mended normal word-space value to be used with this font. NORM_SPACE can be approximated if not provided as a font property, according to the following algorithm: DeciPointsPerInch = 722.7 if (NORM_SPACE undefined) then if (SPACE glyph exists) then NORM_SPACE = width of SPACE else NORM_SPACE = ROUND((0.33 * RESOLUTION_X * POINT_SIZE)/ DeciPointsPerInch) 3.2.17. MAX_SPACE MAX_SPACE is an integer value (of type INT32) that gives the recommended maximum word-space value to be used with this font. MAX_SPACE can be approximated if not provided as a font property, according to the following algorithm: if (MAX_SPACE undefined) then MAX_SPACE = ROUND(1.5 * NORM_SPACE) 3.2.18. END_SPACE END_SPACE is an integer value (of type INT32) that gives the recommended spacing at the end of sentences. END_SPACE can be approximated if not provided as a font property, according to the following algorithm: if (END_SPACE undefined) then END_SPACE = NORM_SPACE 3.2.19. AVG_CAPITAL_WIDTH AVG_CAPITAL_WIDTH is an integer value (of type INT32) that gives the unweighted arithmetic mean of the absolute value of the width of each 18 X Logical Font Description Conventions X11, Release 6.4 capital glyph in the font, in tenths of pixels, multiplied by -1 if the dominant writing direction for the font is right-to-left. This property applies to both Latin and non-Latin fonts. For Latin fonts, capitals are the glyphs A through Z. This property is usually used for font matching or substitution. AVG_CAPITAL_WIDTH can be calculated if not provided as a font property, according to the following algorithm: if (AVG_CAPITAL_WIDTH undefined) then if (capitals exist) then AVG_CAPITAL_WIDTH = ROUND (MEAN (ABS (width of each capital glyph)) * 10) * (if (dominant writing direction L-to-R) then 1 else -1) else AVG_CAPITAL_WIDTH undefined 3.2.20. AVG_LOWERCASE_WIDTH AVG_LOWERCASE_WIDTH is an integer value (of type INT32) that gives the unweighted arithmetic mean width of the absolute value of the width of each lowercase glyph in the font in tenths of pixels, multiplied by -1 if the dominant writing direction for the font is right-to-left. For Latin fonts, lowercase are the glyphs a through z. This property is usually used for font matching or substitution. Where appropriate, AVG_LOWERCASE_WIDTH can be approximated if not pro- vided as a font property, according to the following algorithm: if (AVG_LOWERCASE_WIDTH undefined) then if (lowercase exists) then AVG_LOWERCASE_WIDTH = ROUND (MEAN (ABS (width of each lowercase glyph)) * 10) * (if (dominant writing direction L-to-R) then 1 else -1) else AVG_LOWERCASE_WIDTH undefined 3.2.21. QUAD_WIDTH QUAD_WIDTH is an integer typographic metric (of type INT32) that gives the width of a quad (em) space. Note Because all typographic fixed spaces (em, en, and thin) are constant for a given font size (that is, they do not vary according to setwidth), the use of this font property has been deprecated. X clients that require typographic fixed space values are encouraged to discontinue use of QUAD_WIDTH and compute these values from other font properties (for example, PIXEL_SIZE). X clients that require a font-dependent width value should use either the FIGURE_WIDTH or one of the average 19 X Logical Font Description Conventions X11, Release 6.4 character width font properties (AVERAGE_WIDTH, AVG_CAPI- TAL_WIDTH or AVG_LOWERCASE_WIDTH). 3.2.22. FIGURE_WIDTH FIGURE_WIDTH is an integer typographic metric (of type INT32) that gives the width of the tabular figures and the dollar sign, if suitable for tabular setting (all widths equal). For Latin fonts, these tabular fig- ures are the Arabic numerals 0 through 9. FIGURE_WIDTH can be approximated if not supplied as a font property, according to the following algorithm: if (numerals and DOLLAR sign are defined & widths are equal) then FIGURE_WIDTH = width of DOLLAR else FIGURE_WIDTH property undefined 3.2.23. SUPERSCRIPT_X SUPERSCRIPT_X is an integer value (of type INT32) that gives the recom- mended horizontal offset in pixels from the position point to the X ori- gin of synthetic superscript text. If the current position point is at [X,Y], then superscripts should begin at [X + SUPERSCRIPT_X, Y - SUPER- SCRIPT_Y]. SUPERSCRIPT_X can be approximated if not provided as a font property, according to the following algorithm: if (SUPERSCRIPT_X undefined) then if (TANGENT(ITALIC_ANGLE) defined) then SUPERSCRIPT_X = ROUND((0.40 * CAP_HEIGHT) / TANGENT(ITALIC_ANGLE)) else SUPERSCRIPT_X = ROUND(0.40 * CAP_HEIGHT) where TANGENT is a trigonometric function that returns the tangent of its argument, which is in 1/64 degrees. 3.2.24. SUPERSCRIPT_Y SUPERSCRIPT_Y is an integer value (of type INT32) that gives the recom- mended vertical offset in pixels from the position point to the Y origin of synthetic superscript text. If the current position point is at [X,Y], then superscripts should begin at [X + SUPERSCRIPT_X, Y - SUPER- SCRIPT_Y]. SUPERSCRIPT_Y can be approximated if not provided as a font property, according to the following algorithm: 20 X Logical Font Description Conventions X11, Release 6.4 if (SUPERSCRIPT_Y undefined) then SUPERSCRIPT_Y = ROUND(0.40 * CAP_HEIGHT) 3.2.25. SUBSCRIPT_X SUBSCRIPT_X is an integer value (of type INT32) that gives the recom- mended horizontal offset in pixels from the position point to the X ori- gin of synthetic subscript text. If the current position point is at [X,Y], then subscripts should begin at [X + SUBSCRIPT_X, Y + SUB- SCRIPT_Y]. SUBSCRIPT_X can be approximated if not provided as a font property, according to the following algorithm: if (SUBSCRIPT_X undefined) then if (TANGENT(ITALIC_ANGLE) defined) then SUBSCRIPT_X = ROUND((0.40 * CAP_HEIGHT) / TANGENT(ITALIC_ANGLE)) else SUBSCRIPT_X = ROUND(0.40 * CAP_HEIGHT) 3.2.26. SUBSCRIPT_Y SUBSCRIPT_Y is an integer value (of type INT32) that gives the recom- mended vertical offset in pixels from the position point to the Y origin of synthetic subscript text. If the current position point is at [X,Y], then subscripts should begin at [X + SUBSCRIPT_X, Y + SUBSCRIPT_Y]. SUBSCRIPT_Y can be approximated if not provided as a font property, according to the following algorithm: if (SUBSCRIPT_Y undefined) then SUBSCRIPT_Y = ROUND(0.40 * CAP_HEIGHT) 3.2.27. SUPERSCRIPT_SIZE SUPERSCRIPT_SIZE is an integer value (of type INT32) that gives the rec- ommended body size of synthetic superscripts to be used with this font, in pixels. This will generally be smaller than the size of the current font; that is, superscripts are imaged from a smaller font offset according to SUPERSCRIPT_X and SUPERSCRIPT_Y. SUPERSCRIPT_SIZE can be approximated if not provided as a font property, according to the following algorithm: if (SUPERSCRIPT_SIZE undefined) then SUPERSCRIPT_SIZE = ROUND(0.60 * PIXEL_SIZE) 21 X Logical Font Description Conventions X11, Release 6.4 3.2.28. SUBSCRIPT_SIZE SUBSCRIPT_SIZE is an integer value (of type INT32) that gives the recom- mended body size of synthetic subscripts to be used with this font, in pixels. As with SUPERSCRIPT_SIZE, this will generally be smaller than the size of the current font; that is, subscripts are imaged from a smaller font offset according to SUBSCRIPT_X and SUBSCRIPT_Y. SUBSCRIPT_SIZE can be approximated if not provided as a font property, according to the algorithm: if (SUBSCRIPT_SIZE undefined) then SUBSCRIPT_SIZE = ROUND(0.60 * PIXEL_SIZE) 3.2.29. SMALL_CAP_SIZE SMALL_CAP_SIZE is an integer value (of type INT32) that gives the recom- mended body size of synthetic small capitals to be used with this font, in pixels. Small capitals are generally imaged from a smaller font of slightly more weight. No offset [X,Y] is necessary. SMALL_CAP_SIZE can be approximated if not provided as a font property, according to the following algorithm: if (SMALL_CAP_SIZE undefined) then SMALL_CAP_SIZE = ROUND(PIXEL_SIZE * ((X_HEIGHT + ((CAP_HEIGHT - X_HEIGHT) / 3)) / CAP_HEIGHT)) 3.2.30. UNDERLINE_POSITION UNDERLINE_POSITION is an integer value (of type INT32) that gives the recommended vertical offset in pixels from the baseline to the top of the underline. If the current position point is at [X,Y], the top of the baseline is given by [X, Y + UNDERLINE_POSITION]. UNDERLINE_POSITION can be approximated if not provided as a font prop- erty, according to the following algorithm: if (UNDERLINE_POSITION undefined) then UNDERLINE_POSITION = ROUND((maximum descent) / 2) where maximum descent is the maximum descent (below the baseline) in pixels of any glyph in the font. 3.2.31. UNDERLINE_THICKNESS UNDERLINE_THICKNESS is an integer value (of type INT32) that gives the recommended underline thickness, in pixels. 22 X Logical Font Description Conventions X11, Release 6.4 UNDERLINE_THICKNESS can be approximated if not provided as a font prop- erty, according to the following algorithm: CapStemWidth = average width of the stems of capitals if (UNDERLINE_THICKNESS undefined) then UNDERLINE_THICKNESS = CapStemWidth 3.2.32. STRIKEOUT_ASCENT STRIKEOUT_ASCENT is an integer value (of type INT32) that gives the ver- tical ascent for boxing or voiding glyphs in this font. If the current position is at [X,Y] and the string extent is EXTENT, the upper-left corner of the strikeout box is at [X, Y - STRIKEOUT_ASCENT] and the lower-right corner of the box is at [X + EXTENT, Y + STRIKEOUT_DESCENT]. STRIKEOUT_ASCENT can be approximated if not provided as a font property, according to the following algorithm: if (STRIKEOUT_ASCENT undefined) STRIKEOUT_ASCENT = maximum ascent where maximum ascent is the maximum ascent (above the baseline) in pix- els of any glyph in the font. 3.2.33. STRIKEOUT_DESCENT STRIKEOUT_DESCENT is an integer value (of type INT32) that gives the vertical descent for boxing or voiding glyphs in this font. If the cur- rent position is at [X,Y] and the string extent is EXTENT, the upper- left corner of the strikeout box is at [X, Y - STRIKEOUT_ASCENT] and the lower-right corner of the box is at [X + EXTENT, Y + STRIKEOUT_DESCENT]. STRIKEOUT_DESCENT can be approximated if not provided as a font prop- erty, according to the following algorithm: if (STRIKEOUT_DESCENT undefined) STRIKEOUT_DESCENT = maximum descent where maximum descent is the maximum descent (below the baseline) in pixels of any glyph in the font. 3.2.34. ITALIC_ANGLE ITALIC_ANGLE is an integer value (of type INT32) that gives the nominal posture angle of the typeface design, in 1/64 degrees, measured from the glyph origin counterclockwise from the three o'clock position. ITALIC_ANGLE can be defaulted if not provided as a font property, according to the following algorithm: 23 X Logical Font Description Conventions X11, Release 6.4 if (ITALIC_ANGLE undefined) then ITALIC_ANGLE = (90 * 64) 3.2.35. CAP_HEIGHT CAP_HEIGHT is an integer value (of type INT32) that gives the nominal height of the capital letters contained in the font, as specified by the FOUNDRY or typeface designer. Certain clients require CAP_HEIGHT to compute scale factors and posi- tioning offsets for synthesized glyphs where this information or designed glyphs are not explicitly provided by the font (for example, small capitals, superiors, inferiors, and so on). CAP_HEIGHT is also a critical factor in font matching and substitution. CAP_HEIGHT can be approximated if not provided as a font property, according to the following algorithm: if (CAP_HEIGHT undefined) then if (Latin font) then CAP_HEIGHT = XCharStruct.ascent[glyph X] else if (capitals exist) then CAP_HEIGHT = XCharStruct.ascent[some unaccented capital glyph] else CAP_HEIGHT undefined 3.2.36. X_HEIGHT X_HEIGHT is an integer value (of type INT32) that gives the nominal height above the baseline of the lowercase glyphs contained in the font, as specified by the FOUNDRY or typeface designer. As with CAP_HEIGHT, X_HEIGHT is required by certain clients to compute scale factors for synthesized small capitals where this information is not explicitly provided by the font resource. X_HEIGHT is a critical factor in font matching and substitution. X_HEIGHT can be approximated if not provided as a font property, accord- ing to the following algorithm: if (X_HEIGHT undefined) then if (Latin font) then X_HEIGHT = XCharStruct.ascent[glyph x] else if (lowercase exists) then X_HEIGHT = XCharStruct.ascent[some unaccented lc glyph without an ascender] else X_HEIGHT undefined 24 X Logical Font Description Conventions X11, Release 6.4 3.2.37. RELATIVE_SETWIDTH RELATIVE_SETWIDTH is an unsigned integer value (of type CARD32) that gives the coded proportionate width of the font, relative to all known fonts of the same typeface family, according to the type designer's or FOUNDRY's judgment. RELATIVE_SETWIDTH ranges from 10 to 90 or is 0 if undefined or unknown. The following reference values are defined: --------------------------------------------------------------------------- Code English Translation Description --------------------------------------------------------------------------- 0 Undefined Undefined or unknown 10 UltraCondensed The lowest ratio of average width to height 20 ExtraCondensed 30 Condensed Condensed, Narrow, Compressed, ... 40 SemiCondensed 50 Medium Medium, Normal, Regular, ... 60 SemiExpanded SemiExpanded, DemiExpanded, ... 70 Expanded 80 ExtraExpanded ExtraExpanded, Wide, ... 90 UltraExpanded The highest ratio of average width to height --------------------------------------------------------------------------- RELATIVE_SETWIDTH can be defaulted if not provided as a font property, according to the following algorithm: if (RELATIVE_SETWIDTH undefined) then RELATIVE_SETWIDTH = 50 For polymorphic fonts, RELATIVE_SETWIDTH is not necessarily a linear function of the font's setwidth axis. X clients that want to obtain a calculated proportionate width of the font (that is, a font-independent way of identifying the proportionate width across all fonts and all font vendors) can use the following algo- rithm: SETWIDTH = AVG_CAPITAL_WIDTH / (CAP_HEIGHT * 10) where SETWIDTH is a real number with zero being the narrowest calculated setwidth. 3.2.38. RELATIVE_WEIGHT RELATIVE_WEIGHT is an unsigned integer value (of type CARD32) that gives the coded weight of the font, relative to all known fonts of the same typeface family, according to the type designer's or FOUNDRY's judgment. 25 X Logical Font Description Conventions X11, Release 6.4 RELATIVE_WEIGHT ranges from 10 to 90 or is 0 if undefined or unknown. The following reference values are defined: ----------------------------------------------------------------------- Code English Translation Description ----------------------------------------------------------------------- 0 Undefined Undefined or unknown 10 UltraLight The lowest ratio of stem width to height 20 ExtraLight 30 Light 40 SemiLight SemiLight, Book, ... 50 Medium Medium, Normal, Regular,... 60 SemiBold SemiBold, DemiBold, ... 70 Bold 80 ExtraBold ExtraBold, Heavy, ... 90 UltraBold UltraBold, Black, ..., the highest ratio of stem width to height ----------------------------------------------------------------------- RELATIVE_WEIGHT can be defaulted if not provided as a font property, according to the following algorithm: if (RELATIVE_WEIGHT undefined) then RELATIVE_WEIGHT = 50 For polymorphic fonts, RELATIVE_WEIGHT is not necessarily a linear func- tion of the font's weight axis. 3.2.39. WEIGHT Calculated WEIGHT is an unsigned integer value (of type CARD32) that gives the calculated weight of the font, computed as the ratio of capi- tal stem width to CAP_HEIGHT, in the range 0 to 1000, where 0 is the lightest weight. WEIGHT can be calculated if not supplied as a font property, according to the following algorithm: CapStemWidth = average width of the stems of capitals if (WEIGHT undefined) then WEIGHT = ROUND ((CapStemWidth * 1000) / CAP_HEIGHT) A calculated value for weight is necessary when matching fonts from dif- ferent families because both the RELATIVE_WEIGHT and the WEIGHT_NAME are assigned by the typeface supplier, according to its tradition and prac- tice, and therefore, are somewhat subjective. Calculated WEIGHT pro- vides a font-independent way of identifying the weight across all fonts and all font vendors. 26 X Logical Font Description Conventions X11, Release 6.4 3.2.40. RESOLUTION RESOLUTION is an integer value (of type INT32) that gives the resolution for which this font was created, measured in 1/100 pixels per point. Note As independent horizontal and vertical design resolution com- ponents are required to accommodate displays with nonsquare aspect ratios, the use of this font property has been depre- cated, and independent RESOLUTION_X and RESOLUTION_Y font name fields/properties have been defined (see sections 3.1.2.9 and 3.1.2.10). X clients are encouraged to discontinue use of the RESOLUTION property and are encouraged to use the appropriate X,Y resolution properties, as required. 3.2.41. FONT FONT is a string (of type ATOM) that gives the full XLFD name of the font--that is, the value can be used to open another instance of the same font. If not provided, the FONT property cannot be calculated. 3.2.42. FACE_NAME FACE_NAME is a human-understandable string (of type ATOM) that gives the full device-independent typeface name, including the owner, weight, slant, set, and so on but not the resolution, size, and so on. This property may be used as feedback during font selection. FACE_NAME cannot be calculated or approximated if not provided as a font property. 3.2.43. FULL_NAME FULL_NAME is the same as FACE_NAME. Its use is deprecated, but it is found on some old fonts. 3.2.44. COPYRIGHT COPYRIGHT is a human-understandable string (of type ATOM) that gives the copyright information of the legal owner of the digital font data. This information is a required component of a font but is independent of the particular format used to represent it (that is, it cannot be cap- tured as a comment that could later be thrown away for efficiency rea- sons). COPYRIGHT cannot be calculated or approximated if not provided as a font property. 27 X Logical Font Description Conventions X11, Release 6.4 3.2.45. NOTICE NOTICE is a human-understandable string (of type ATOM) that gives the copyright information of the legal owner of the font design or, if not applicable, the trademark information for the typeface FAMILY_NAME. Typeface design and trademark protection laws vary from country to coun- try, the USA having no design copyright protection currently while vari- ous countries in Europe offer both design and typeface family name trademark protection. As with COPYRIGHT, this information is a required component of a font but is independent of the particular format used to represent it. NOTICE cannot be calculated or approximated if not provided as a font property. 3.2.46. DESTINATION DESTINATION is an unsigned integer code (of type CARD32) that gives the font design destination, that is, whether it was designed as a screen proofing font to match printer font glyph widths (WYSIWYG), as an opti- mal video font (possibly with corresponding printer font) for extended screen viewing (video text), and so on. The font design considerations are very different, and at current dis- play resolutions, the readability and legibility of these two kinds of screen fonts are very different. DESTINATION allows publishing clients that use X to model the printed page and video text clients, such as on- line documentation browsers, to query for X screen fonts that suit their particular requirements. The encoding is as follows: -------------------------------------------------------------------- Code English Translation Description -------------------------------------------------------------------- 0 WYSIWYG The font is optimized to match the typographic design and metrics of an equivalent printer font. 1 Video text The font is optimized for screen leg- ibility and readability. -------------------------------------------------------------------- 3.2.47. FONT_TYPE FONT_TYPE is a human-understandable string (of type ATOM) that describes the format of the font data as they are read from permanent storage by the current font source. It is a static attribute of the source data. It can be used by clients to select a type of bitmap or outline font without regard to the rasterizer used to render the font. 28 X Logical Font Description Conventions X11, Release 6.4 Predefined values are as follows: ---------------------------------------------------------------- Value When applicable ---------------------------------------------------------------- "Bitmap" Hand-tuned bitmap fonts. Some attempt has been made to optimize the visual appearance of the font for the requested size and resolution. "Prebuilt" All bitmap format fonts that cannot be described as "Bitmap", that is, hand-tuned. For example, a bitmap format font that was generated mechanically using a scalable font rasterizer would be consid- ered "Prebuilt", not "Bitmap". "Type 1" Any Type 1 font. "TrueType" Any TrueType font. "Speedo" Any Speedo font. "F3" Any F3 font. ---------------------------------------------------------------- Other values may be registered with the X Consortium. 3.2.48. FONT_VERSION FONT_VERSION is a human-understandable string (of type ATOM) that describes the formal or informal version of the font. None is a valid value. 3.2.49. RASTERIZER_NAME RASTERIZER_NAME is a human-understandable string (of type ATOM) that is the specific name of the rasterizer that has performed some rasteriza- tion operation (such as scaling from outlines) on this font. To define a RASTERIZER_NAME, the following format is recommended: RasterizerName ::= OrganizationId Space Rasterizer OrganizationId ::= STRING8--the X Registry ORGANIZATION name of the rasterizer implementor or maintainer. Rasterizer ::= the case-sensitive, human-understand- able product name of the rasterizer. Words within this name should be sep- arated by a single SPACE. Space ::= OCTET-" " (SPACE) Examples: X Consortium Bit Scaler X Consortium Type 1 Rasterizer X Consortium Speedo Rasterizer Adobe Type Manager Sun TypeScaler 29 X Logical Font Description Conventions X11, Release 6.4 If RASTERIZER_NAME is not defined, or is None, no rasterization opera- tion has been applied to the FONT_TYPE. 3.2.50. RASTERIZER_VERSION RASTERIZER_VERSION is a human-understandable string (of type ATOM) that represents the formal or informal version of a font rasterizer. The RASTERIZER_VERSION should match the corresponding product version number known to users, when applicable. 3.2.51. RAW_ASCENT For a font with a transformation matrix, RAW_ASCENT is the font ascent in 1000 pixel metrics (see section 4.1). 3.2.52. RAW_DESCENT For a font with a transformation matrix, RAW_DESCENT is the font descent in 1000 pixel metrics (see section 4.1). 3.2.53. RAW_* For a font with a transformation matrix, all font properties that repre- sent horizontal or vertical sizes or displacements will be accompanied by a new property, named as the original except prefixed with "RAW_", that is computed as described in section 4.1. 3.2.54. AXIS_NAMES AXIS_NAMES is a list of all the names of the axes for a polymorphic font, separated by a null (0) byte. These names are suitable for pre- sentation in a user interface (see section 6). 3.2.55. AXIS_LIMITS AXIS_LIMITS is a list of integers, two for each axis, giving the minimum and maximum allowable values for that axis of a polymorphic font (see section 6). 3.2.56. AXIS_TYPES AXIS_TYPES is like AXIS_NAMES, but can be registered as having specific semantics (see section 6). 3.3. Built-in Font Property Atoms The following font property atom definitions were predefined in the ini- tial version of the core protocol: ---------------------------------------------- Font Property/Atom Name Property Type ---------------------------------------------- MIN_SPACE INT32 30 X Logical Font Description Conventions X11, Release 6.4 ---------------------------------------------- Font Property/Atom Name Property Type ---------------------------------------------- NORM_SPACE INT32 MAX_SPACE INT32 END_SPACE INT32 SUPERSCRIPT_X INT32 SUPERSCRIPT_Y INT32 SUBSCRIPT_X INT32 SUBSCRIPT_Y INT32 UNDERLINE_POSITION INT32 UNDERLINE_THICKNESS INT32 STRIKEOUT_ASCENT INT32 STRIKEOUT_DESCENT INT32 FONT_ASCENT INT32 FONT_DESCENT INT32 ITALIC_ANGLE INT32 X_HEIGHT INT32 QUAD_WIDTH INT32 - deprecated WEIGHT CARD32 POINT_SIZE INT32 RESOLUTION CARD32 - deprecated COPYRIGHT ATOM FULL_NAME ATOM - deprecated FAMILY_NAME ATOM DEFAULT_CHAR CARD32 ---------------------------------------------- 4. Matrix Transformations An XLFD name presented to the server can have the POINT_SIZE or PIXEL_SIZE field begin with the character "[". If the first character of the field is "[", the character must be followed with ASCII represen- tations of four floating point numbers and a trailing "]", with white space separating the numbers and optional white space separating the numbers from the "[" and "]" characters. Numbers use standard floating point syntax but use the character "~" to represent a minus sign in the mantissa or exponent. The BNF for a matrix transformation string is as follows: MatrixString ::= LeftBracket OptionalSpace Float Space Float Space Float Space Float OptionalSpace RightBracket OptionalSpace ::= "" | Space Space ::= SpaceChar | SpaceChar Space Float ::= Mantissa | Mantissa Exponent Mantissa ::= Sign Number | Number Sign ::= Plus | Tilde Number ::= Integer | Integer Dot Integer | Dot Integer Integer ::= Digit | Digit Integer Digit ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" Exponent ::= "e" SignedInteger | "E" SignedInteger 31 X Logical Font Description Conventions X11, Release 6.4 SignedInteger ::= Sign Integer | Integer LeftBracket ::= OCTET - "[" (LEFT SQUARE BRACKET) RightBracket ::= OCTET - "]" (RIGHT SQUARE BRACKET) SpaceChar ::= OCTET - " " (SPACE) Tilde ::= OCTET - "~" (TILDE) Plus ::= OCTET - "+" (PLUS) Dot ::= OCTET - "." (FULL STOP) The string "[a b c d]" represents a graphical transformation of the glyphs in the font by the matrix [ a b 0 ] [ c d 0 ] [ 0 0 1 ] All transformations occur around the origin of the glyph. The relation- ship between the current scalar values and the matrix transformation values is that the scalar value "N" in the POINT_SIZE field produces the same glyphs as the matrix "[N/10 0 0 N/10]" in that field, and the scalar value "N" in the PIXEL_SIZE field produces the same glyphs as the matrix "[N*RESOLUTION_X/RESOLUTION_Y 0 0 N]" in that field. If matrices are specified for both the POINT_SIZE and PIXEL_SIZE, they must bear the following relationship to each other within an implementa- tion-specific tolerance: PIXEL_SIZE_MATRIX = [Sx 0 0 Sy] * POINT_SIZE_MATRIX where Sx = RESOLUTION_X / 72.27 Sy = RESOLUTION_Y / 72.27 If either the POINT_SIZE or PIXEL_SIZE field is unspecified (either "0" or wildcarded), the preceding formulas can be used to compute one from the other. 4.1. Metrics and Font Properties In this section, the phrase "1000 pixel metrics" means the metrics that would be obtained if the rasterizer took the base untransformed design used to generate the transformed font and scaled it linearly to a height of 1000 pixels, with no rotation component. Note that there may be no way for the application to actually request this font since the raster- izer may use different outlines or rasterization techniques at that size from the ones used to generate the transformed font. Notes on properties and metrics: The per-char ink metrics (lbearing, rbearing, ascent, and descent) rep- resent the ink extent of the transformed glyph around its origin. The per-char width is the x component of the transformed character width. 32 X Logical Font Description Conventions X11, Release 6.4 The font ascent and descent are the y component of the transformed font ascent or descent. The FONT property returns a name reflecting the matrix being used--that is, the name returned can be used to open another instance of the same font. The returned name is not necessarily an exact copy of the requested name. If, for example, the user requests -misc-fixed-medium-r-normal--0-[2e1 0 0.0 +10.0]-72-72-c-0-iso8859-1 the resulting FONT property might be -misc-fixed-medium-r-normal--[19.9 0 0 10]-[20 0 0 10]-72-72-c-0-iso8859-1 The FONT property will always include matrices in both the PIXEL_SIZE and the POINT_SIZE fields. To allow accurate client positioning of transformed characters, the attributes field of the XCharInfo contains the width of the character in 1000 pixel metrics. This attributes field should be interpreted as a signed integer. There will always be 2 new font properties defined, RAW_ASCENT and RAW_DESCENT, that hold the ascent and descent in 1000 pixel metrics. All font properties that represent horizontal widths or displacements have as their value the x component of the transformed width or dis- placement. All font properties that represent vertical heights or dis- placements have as their value the y component of the transformed height or displacement. Each such property will be accompanied by a new prop- erty, named as the original except prefixed with "RAW_", that gives the value of the width, height, or displacement in 1000 pixel metrics. 5. Scalable Fonts The XLFD is designed to support scalable fonts. A scalable font is a font source from which instances of arbitrary size can be derived. A scalable font source might be one or more outlines together with zero or more hand-tuned bitmap fonts at specific sizes and resolutions, or it might be a programmatic description together with zero or more bitmap fonts, or some other format (perhaps even just a single bitmap font). The following definitions are useful for discussing scalable fonts: Well-formed XLFD pattern A pattern string containing 14 hyphens, one of which is the first character of the pattern. Wildcard characters are permitted in the fields of a well-formed XLFD pattern. Scalable font name A well-formed XLFD pattern containing no wildcards and containing the digit "0" in the PIXEL_SIZE, POINT_SIZE, and AVERAGE_WIDTH fields. 33 X Logical Font Description Conventions X11, Release 6.4 Scalable fields The XLFD fields PIXEL_SIZE, POINT_SIZE, RESOLUTION_X, RESOLUTION_Y, and AVERAGE_WIDTH. Derived instance The result of replacing the scalable fields of a font name with values to yield a font name that could actually be produced from the font source. A scaling engine is permitted, but not required, to interpret the scalable fields in font names to support anamor- phic scaling. Global list The list of names that would be returned by an X server for a List- Fonts protocol request on the pattern "*" if there were no protocol restrictions on the total number of names returned. The global list consists of font names derived from font sources. If a single font source can support multiple character sets (specified in the CHARSET_REGISTRY and CHARSET_ENCODING fields), each such character set should be used to form a separate font name in the list. For a nonscal- able font source, the simple font name for each character set is included in the global list. For a scalable font source, a scalable font name for each character set is included in the list. In addition to the scalable font name, specific derived instance names may also be included in the list. The relative order of derived instances with respect to the scalable font name is not constrained. Finally, font name aliases may also be included in the list. The relative order of aliases with respect to the real font name is not constrained. The values of the RESOLUTION_X and RESOLUTION_Y fields of a scalable font name are implementation dependent, but to maximize backward compat- ibility, they should be reasonable nonzero values, for example, a reso- lution close to that provided by the screen (in a single-screen server). Because some existing applications rely on seeing a collection of point and pixel sizes, server vendors are strongly encouraged in the near term to provide a mechanism for including, for each scalable font name, a set of specific derived instance names. For font sources that contain a collection of hand-tuned bitmap fonts, including names of these instances in the global list is recommended and sufficient. The X protocol request OpenFont on a scalable font name returns a font corresponding to an implementation-dependent derived instance of that font name. The X protocol request ListFonts on a well-formed XLFD pattern returns the following. Starting with the global list, if the actual pattern argument has values containing no wildcards in scalable fields, then substitute each such field into the corresponding field in each scalable font name in the list. For each resulting font name, if the remaining scalable fields cannot be replaced with values to produce a derived 34 X Logical Font Description Conventions X11, Release 6.4 instance, remove the font name from the list. Now take the modified list, and perform a simple pattern match against the pattern argument. ListFonts returns the resulting list. For example, given the global list: -Linotype-Times-Bold-I-Normal--0-0-100-100-P-0-ISO8859-1 -Linotype-Times-Bold-R-Normal--0-0-100-100-P-0-ISO8859-1 -Linotype-Times-Medium-I-Normal--0-0-100-100-P-0-ISO8859-1 -Linotype-Times-Medium-R-Normal--0-0-100-100-P-0-ISO8859-1 a ListFonts request with the pattern: -*-Times-*-R-Normal--*-120-100-100-P-*-ISO8859-1 would return: -Linotype-Times-Bold-R-Normal--0-120-100-100-P-0-ISO8859-1 -Linotype-Times-Medium-R-Normal--0-120-100-100-P-0-ISO8859-1 ListFonts on a pattern containing wildcards that is not a well-formed XLFD pattern is only required to return the list obtained by performing a simple pattern match against the global list. X servers are permit- ted, but not required, to use a more sophisticated matching algorithm. 6. Polymorphic Fonts Fonts that can be varied in ways other than size or resolution are called polymorphic fonts. Multiple Master Type 1 font programs are one type of a polymorphic font. Current examples of axes along which the fonts can be varied are width, weight, and optical size; others might include formality or x-height. To support polymorphic fonts, special values indicating variability are defined for the following XLFD fields: WEIGHT_NAME SLANT SETWIDTH_NAME ADD_STYLE_NAME The string "0" is the special polymorphic value. In the WEIGHT_NAME, SLANT, or SETWIDTH_NAME field, "0" must be the entire field. There may be multiple polymorphic values in the ADD_STYLE_NAME field. They are surrounded by "[" and "]" and separated by a Space, as "[0 0]". The polymorphic values may coexist with other data in the field. It is rec- ommended that the polymorphic values be at the end of the ADD_STYLE_NAME field. The font-matching algorithms for a font with polymorphic fields are identical to the matching algorithms for a font with scalable fields. 35 X Logical Font Description Conventions X11, Release 6.4 There are three new font properties to describe the axes of variation, AXIS_NAMES, AXIS_LIMITS, and AXIS_TYPES. AXIS_NAMES is a list of all the names of the axes for the font, separated by a null (0) byte. These names are suitable for presentation in a user interface. AXIS_LIMITS is a list of integers, two for each axis, giving the minimum and maximum allowable values for that axis. AXIS_TYPES is like AXIS_NAMES, but can be registered as having specific semantics. The axes are listed in the properties in the same order as they appear in the font name. They are matched with font name fields by looking for the special polymorphic values in the font name. Examples: The Adobe Myriad MM font program has width and weight axes. Weight can vary from 215 to 830, and width from 300 to 700. Name: -Adobe-Myriad MM-0-R-0--0-0-0-0-P-0-ISO8859-1 AXIS_NAMES: Weight, Width AXIS_LIMITS: 215, 830, 300, 700 AXIS_TYPES: Adobe-Weight, Adobe-Width Sample derived instance: -Adobe-Myriad MM-412-R-575--*-120-100-100-P-*-ISO8859-1 The Adobe Minion MM Italic font program has width, weight, and optical size axes. Name: -Adobe-Minion MM-0-I-0-[0]-0-0-0-0-P-0-ISO8859-1 AXIS_NAMES: Weight, Width, Optical size AXIS_LIMITS: 345, 620, 450, 600, 6, 72 AXIS_TYPES: Adobe-Weight, Adobe-Width, Adobe-OpticalSize Sample derived instance: -Adobe-Minion MM-550-I-480-[18]-*-180-100-100-P-*-ISO8859-1 The Adobe Minion MM Swash Italic font program has the same axes and val- ues. This shows how "[0]" in the ADD_STYLE_NAME field can coexist with other words. Name: -Adobe-Minion MM-0-I-0-Swash[0]-0-0-0-0-P-0-ISO8859-1 AXIS_NAMES: Weight, Width, Optical size AXIS_LIMITS: 345, 620, 450, 600, 6, 72 36 X Logical Font Description Conventions X11, Release 6.4 AXIS_TYPES: Adobe-Weight, Adobe-Width, Adobe-OpticalSize Sample derived instance: -Adobe-Minion MM-550-I-480-Swash[18]-*-180-100-100-P-*-ISO8859-1 The XYZ Abc font, a hypothetical font, has optical size and x-height axes. This shows how there can be more than one polymorphic value in the ADD_STYLE_NAME field. Name: -XYZ-Abc-Medium-R-Normal-[0 0]-0-0-0-0-P-0-ISO8859-1 AXIS_NAMES: Optical size, X-height AXIS_LIMITS: 6, 72, 400, 600 AXIS_TYPES: XYZ-OpticalSize, XYZ-Xheight Sample derived instance: -XYZ-Abc-Medium-R-Normal-[14 510]-*-140-100-100-P-*-ISO8859-1 If an axis allows negative values, a client requests a negative value by using "~" (TILDE) as a minus sign. Axis types can be registered with the X Consortium, along with their semantics. If a font name that contains the polymorphic value or a wildcard in a polymorphic field is presented to a font source, the font source is free to substitute any value that is convenient. However, font sources should try to use a value that would be considered normal or medium for the particular font. For example, if an optical size variable is unre- solved, the font source should provide a value appropriate to the size of the font. The result of specifying an out-of-range value for a polymorphic field is undefined. The font source may treat this as a BadName error, treat the value as if it were the closest legal value, or extrapolate to try to accommodate the value. 7. Affected Elements of Xlib and the X Protocol The following X protocol requests must support the XLFD conventions: o OpenFont - for the name argument o ListFonts - for the pattern argument o ListFontsWithInfo - for the pattern argument In addition, the following Xlib functions must support the XLFD conven- tions: 37 X Logical Font Description Conventions X11, Release 6.4 o XLoadFont - for the name argument o XListFontsWithInfo - for the pattern argument o XLoadQueryFont - for the name argument o XListFonts - for the pattern argument 8. BDF Conformance The bitmap font distribution and interchange format adopted by the X Consortium (BDF V2.1) provides a general mechanism for identifying the font name of an X font and a variable list of font properties, but it does not mandate the syntax or semantics of the font name or the seman- tics of the font properties that might be provided in a BDF font. This section identifies the requirements for BDF fonts that conform to XLFD. 8.1. XLFD Conformance Requirements A BDF font conforms to the XLFD specification if and only if the follow- ing conditions are satisfied: o The value for the BDF item FONT conforms to the syntax and semantic definition of a XLFD FontName string. o The FontName begins with the X FontNameRegistry prefix: "-". o All XLFD FontName fields are defined. o Any FontProperties provided conform in name and semantics to the XLFD FontProperty definitions. A simple method of testing for conformance would entail verifying that the FontNameRegistry prefix is the string "-", that the number of field delimiters in the string and coded field values are valid, and that each font property name either matches a standard XLFD property name or fol- lows the definition of a private property. 8.2. FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR are provided in the BDF specification as properties that are moved to the XFontStruct by the BDF font compiler in generating the X server-specific binary font encoding. If present, these properties shall comply with the following semantic definitions. 8.2.1. FONT_ASCENT FONT_ASCENT is an integer value (of type INT32) that gives the recom- mended typographic ascent above the baseline for determining interline spacing. Specific glyphs of the font may extend beyond this. If the current position point for line n is at [X,Y], then the origin of the next line m = n + 1 (allowing for a possible font change) is [X, Y + FONT_DESCENTn + FONT_ASCENTm]. 38 X Logical Font Description Conventions X11, Release 6.4 FONT_ASCENT can be approximated if not provided as a font property, according to the following algorithm: if (FONT_ASCENT undefined) then FONT_ASCENT = maximum ascent where maximum ascent is the maximum ascent (above the baseline) in pix- els of any glyph in the font. 8.2.2. FONT_DESCENT FONT_DESCENT is an integer value (of type INT32) that gives the recom- mended typographic descent below the baseline for determining interline spacing. Specific glyphs of the font may extend beyond this. If the current position point for line n is at [X,Y], then the origin of the next line m = n+1 (allowing for a possible font change) is [X, Y + FONT_DESCENTn + FONT_ASCENTm]. The logical extent of the font is inclusive between the Y-coordinate values: Y - FONT_ASCENT and Y + FONT_DESCENT + 1. FONT_DESCENT can be approximated if not provided as a font property, according to the following algorithm: if (FONT_DESCENT undefined) then FONT_DESCENT = maximum descent where maximum descent is the maximum descent (below the baseline) in pixels of any glyph in the font. 8.2.3. DEFAULT_CHAR The DEFAULT_CHAR is an unsigned integer value (of type CARD32) that specifies the index of the default character to be used by the X server when an attempt is made to display an undefined or nonexistent character in the font. (For a font using a 2-byte matrix format, the index bytes are encoded in the integer as byte1 * 65536 + byte2.) If the DEFAULT_CHAR itself specifies an undefined or nonexistent character in the font, then no display is performed. DEFAULT_CHAR cannot be approximated if not provided as a font property. 39 X Logical Font Description Conventions X11, Release 6.4 40 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. Requirements and Goals . . . . . . . . . . . . . . . . . . . . . 1 2.1. Provide Unique and Descriptive Font Names . . . . . . . . . . . 2 2.2. Support Multiple Font Vendors and Character Sets . . . . . . . 2 2.3. Support Scalable and Polymorphic Fonts . . . . . . . . . . . . 2 2.4. Support Transformations and Subsetting of Fonts . . . . . . . . 2 2.5. Be Independent of X Server and Operating or File System Implementations . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.6. Support Arbitrarily Complex Font Matching and Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.7. Be Extensible . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. X Logical Font Description . . . . . . . . . . . . . . . . . . . 3 3.1. FontName . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1.1. FontName Syntax . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.2. FontName Field Definitions . . . . . . . . . . . . . . . . . 5 3.1.2.1. FOUNDRY Field . . . . . . . . . . . . . . . . . . . . . . . 5 3.1.2.2. FAMILY_NAME Field . . . . . . . . . . . . . . . . . . . . . 6 3.1.2.3. WEIGHT_NAME Field . . . . . . . . . . . . . . . . . . . . . 6 3.1.2.4. SLANT Field . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1.2.5. SETWIDTH_NAME Field . . . . . . . . . . . . . . . . . . . . 7 3.1.2.6. ADD_STYLE_NAME Field . . . . . . . . . . . . . . . . . . . 8 3.1.2.7. PIXEL_SIZE Field . . . . . . . . . . . . . . . . . . . . . 8 3.1.2.8. POINT_SIZE Field . . . . . . . . . . . . . . . . . . . . . 8 3.1.2.9. RESOLUTION_X and RESOLUTION_Y Fields . . . . . . . . . . . 9 3.1.2.10. SPACING Field . . . . . . . . . . . . . . . . . . . . . . 9 3.1.2.11. AVERAGE_WIDTH Field . . . . . . . . . . . . . . . . . . . 10 3.1.2.12. CHARSET_REGISTRY and CHARSET_ENCODING Fields . . . . . . . 10 3.1.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2. Font Properties . . . . . . . . . . . . . . . . . . . . . . . . 13 3.2.1. FOUNDRY . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.2. FAMILY_NAME . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.3. WEIGHT_NAME . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.4. SLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.5. SETWIDTH_NAME . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.6. ADD_STYLE_NAME . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.7. PIXEL_SIZE . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2.8. POINT_SIZE . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2.9. RESOLUTION_X . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2.10. RESOLUTION_Y . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2.11. SPACING . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.2.12. AVERAGE_WIDTH . . . . . . . . . . . . . . . . . . . . . . . 17 3.2.13. CHARSET_REGISTRY . . . . . . . . . . . . . . . . . . . . . . 17 3.2.14. CHARSET_ENCODING . . . . . . . . . . . . . . . . . . . . . . 17 3.2.15. MIN_SPACE . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.2.16. NORM_SPACE . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.2.17. MAX_SPACE . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.2.18. END_SPACE . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.2.19. AVG_CAPITAL_WIDTH . . . . . . . . . . . . . . . . . . . . . 18 3.2.20. AVG_LOWERCASE_WIDTH . . . . . . . . . . . . . . . . . . . . 19 3.2.21. QUAD_WIDTH . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.2.22. FIGURE_WIDTH . . . . . . . . . . . . . . . . . . . . . . . . 20 i X Logical Font Description Conventions X11, Release 6.4 3.2.23. SUPERSCRIPT_X . . . . . . . . . . . . . . . . . . . . . . . 20 3.2.24. SUPERSCRIPT_Y . . . . . . . . . . . . . . . . . . . . . . . 20 3.2.25. SUBSCRIPT_X . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2.26. SUBSCRIPT_Y . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2.27. SUPERSCRIPT_SIZE . . . . . . . . . . . . . . . . . . . . . . 21 3.2.28. SUBSCRIPT_SIZE . . . . . . . . . . . . . . . . . . . . . . . 22 3.2.29. SMALL_CAP_SIZE . . . . . . . . . . . . . . . . . . . . . . . 22 3.2.30. UNDERLINE_POSITION . . . . . . . . . . . . . . . . . . . . . 22 3.2.31. UNDERLINE_THICKNESS . . . . . . . . . . . . . . . . . . . . 22 3.2.32. STRIKEOUT_ASCENT . . . . . . . . . . . . . . . . . . . . . . 23 3.2.33. STRIKEOUT_DESCENT . . . . . . . . . . . . . . . . . . . . . 23 3.2.34. ITALIC_ANGLE . . . . . . . . . . . . . . . . . . . . . . . . 23 3.2.35. CAP_HEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.2.36. X_HEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.2.37. RELATIVE_SETWIDTH . . . . . . . . . . . . . . . . . . . . . 25 3.2.38. RELATIVE_WEIGHT . . . . . . . . . . . . . . . . . . . . . . 25 3.2.39. WEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.2.40. RESOLUTION . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.41. FONT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.42. FACE_NAME . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.43. FULL_NAME . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.44. COPYRIGHT . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.45. NOTICE . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2.46. DESTINATION . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2.47. FONT_TYPE . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2.48. FONT_VERSION . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2.49. RASTERIZER_NAME . . . . . . . . . . . . . . . . . . . . . . 29 3.2.50. RASTERIZER_VERSION . . . . . . . . . . . . . . . . . . . . . 30 3.2.51. RAW_ASCENT . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.52. RAW_DESCENT . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.53. RAW_* . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.54. AXIS_NAMES . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.55. AXIS_LIMITS . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.56. AXIS_TYPES . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.3. Built-in Font Property Atoms . . . . . . . . . . . . . . . . . 30 4. Matrix Transformations . . . . . . . . . . . . . . . . . . . . . 31 4.1. Metrics and Font Properties . . . . . . . . . . . . . . . . . . 32 5. Scalable Fonts . . . . . . . . . . . . . . . . . . . . . . . . . 33 6. Polymorphic Fonts . . . . . . . . . . . . . . . . . . . . . . . . 35 7. Affected Elements of Xlib and the X Protocol . . . . . . . . . . 37 8. BDF Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 38 8.1. XLFD Conformance Requirements . . . . . . . . . . . . . . . . . 38 8.2. FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR . . . . . . . . . . 38 8.2.1. FONT_ASCENT . . . . . . . . . . . . . . . . . . . . . . . . . 38 8.2.2. FONT_DESCENT . . . . . . . . . . . . . . . . . . . . . . . . 39 8.2.3. DEFAULT_CHAR . . . . . . . . . . . . . . . . . . . . . . . . 39 ii