                                Fonts in X11R7.7

                               Juliusz Chroboczek

                            <[1]jch@freedesktop.org>

                           X Version 11, Release 7.7

                                 16 March 2012

   --------------------------------------------------------------------------

                               Table of Contents

   [2]Introduction

                [3]Two font systems

   [4]Installing fonts

                [5]Configuring Xft

                [6]Configuring the core X11 fonts system

   [7]Fonts included with X11R7.7

                [8]Standard bitmap fonts

                [9]The ClearlyU Unicode font family

                [10]Standard scalable fonts

                [11]The Bigelow & Holmes Luxi family

   [12]More about core fonts

                [13]Core fonts and internationalisation

                [14]Additional notes about scalable core fonts

   [15]Appendix: background and terminology

                [16]Characters and glyphs

                [17]Font files, fonts, and XLFD

                [18]Unicode

   [19]References

                                  Introduction

   This document describes the support for fonts in X11R7.7. [20]Installing
   fonts is aimed at the casual user wishing to install fonts in X11R7.7 the
   rest of the document describes the font support in more detail.

   We assume some familiarity with digital fonts. If anything is not clear to
   you, please consult [21]Appendix: background and terminology at the end of
   this document for background information.

  Two font systems

   X11 includes two font systems: the original core X11 fonts system, which
   is present in all implementations of X11, and the Xft fonts system, which
   may not yet be distributed with implementations of X11 that are not based
   on either XFree86 or X11R6.8 or later.

   The core X11 fonts system is directly derived from the fonts system
   included with X11R1 in 1987, which could only use monochrome bitmap fonts.
   Over the years, it has been more or less happily coerced into dealing with
   scalable fonts and rotated glyphs.

   Xft was designed from the start to provide good support for scalable
   fonts, and to do so efficiently. Unlike the core fonts system, it supports
   features such as anti-aliasing and sub-pixel rasterisation. Perhaps more
   importantly, it gives applications full control over the way glyphs are
   rendered, making fine typesetting and WYSIWIG display possible. Finally,
   it allows applications to use fonts that are not installed system-wide for
   displaying documents with embedded fonts.

   Xft is not compatible with the core fonts system: usage of Xft requires
   fairly extensive changes to toolkits (user-interface libraries). While
   X.Org will continue to maintain the core fonts system, toolkit authors are
   encouraged to switch to Xft as soon as possible.

                                Installing fonts

   This section explains how to configure both Xft and the core fonts system
   to access newly-installed fonts.

  Configuring Xft

   Xft has no configuration mechanism itself, it relies upon the
   [22]fontconfig library to configure and customise fonts. That library is
   not specific to the X Window system, and does not rely on any particular
   font output mechanism.

    Installing fonts in Xft

   Fontconfig looks for fonts in a set of well-known directories that include
   all of X11R7.7's standard font directories ("/usr/share/fonts/X11/*") by
   default) as well as a directory called ".fonts/" in the user's home
   directory. Installing a font for use by Xft applications is as simple as
   copying a font file into one of these directories.

 $ cp lucbr.ttf ~/.fonts/

   Fontconfig will notice the new font at the next opportunity and rebuild
   its list of fonts. If you want to trigger this update from the command
   line, you may run the command "fc-cache".

 $ fc-cache

   In order to globally update the system-wide Fontconfig information on Unix
   systems, you will typically need to run this command as root:

 $ su -c fc-cache

    Fine-tuning Xft

   Fontconfig's behaviour is controlled by a set of configuration files: a
   standard configuration file, "/etc/fonts/fonts.conf", a host-specific
   configuration file, "/etc/fonts/local.conf", and a user-specific file
   called ".fonts.conf" in the user's home directory (this can be overridden
   with the "FONTCONFIG_FILE" environment variable).

   Every Fontconfig configuration file must start with the following
   boilerplate:

 <?xml version="1.0"?>
 <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
 <fontconfig>

   In addition, every Fontconfig configuration file must end with the
   following line:

 </fontconfig>

   The default Fontconfig configuration file includes the directory
   "~/.fonts/" in the list of directories searched for font files, and this
   is where user-specific font files should be installed. In the unlikely
   case that a new font directory needs to be added, this can be done with
   the following syntax:

 <dir>/usr/local/share/fonts/</dir>

   Another useful option is the ability to disable anti-aliasing (font
   smoothing) for selected fonts. This can be done with the following syntax:

 <match target="font">
     <test qual="any" name="family">
         <string>Lucida Console</string>
     </test>
     <edit name="antialias" mode="assign">
         <bool>false</bool>
     </edit>
 </match>

   Anti-aliasing can be disabled for all fonts by the following incantation:

 <match target="font">
     <edit name="antialias" mode="assign">
         <bool>false</bool>
     </edit>
 </match>

   Xft supports sub-pixel rasterisation on LCD displays. X11R7.7 should
   automatically enable this feature on laptops and when using an LCD monitor
   connected with a DVI cable; you can check whether this was done by typing

 $ xdpyinfo -ext RENDER | grep sub-pixel

   If this doesn't print anything, you will need to configure Render for your
   particular LCD hardware manually; this is done with the following syntax:

 <match target="font">
     <edit name="rgba" mode="assign">
         <const>rgb</const>
     </edit>
 </match>

   The string "rgb" within the "<const>"..."</const>" specifies the order of
   pixel components on your display, and should be changed to match your
   hardware; it can be one of "rgb" (normal LCD screen), "bgr" (backwards LCD
   screen), "vrgb" (LCD screen rotated clockwise) or "vbgr" (LCD screen
   rotated counterclockwise).

    Configuring applications

   A growing number of applications use Xft in preference to the core fonts
   system. Some applications, however, need to be explicitly configured to
   use Xft.

   A case in point is XTerm, which can be set to use Xft by using the "-fa"
   command line option or by setting the "XTerm*faceName" resource:

 XTerm*faceName: Courier

   or

 $ xterm -fa "Courier"

   For KDE applications, you should select "Anti-alias fonts" in the "Fonts"
   panel of KDE's "Control Center". Note that this option is misnamed: it
   switches KDE to using Xft but doesn't enable anti-aliasing in case it was
   disabled by your Xft configuration file.

   Gnome applications and Mozilla Firefox will use Xft by default.

  Configuring the core X11 fonts system

   Installing fonts in the core system is a two step process. First, you need
   to create a font directory that contains all the relevant font files as
   well as some index files. You then need to inform the X server of the
   existence of this new directory by including it in the font path.

    Installing bitmap fonts

   The X11R7.7 server can use bitmap fonts in both the cross-platform BDF
   format and the somewhat more efficient binary PCF format. (X11R7.7 also
   supports the obsolete SNF format.)

   Bitmap fonts are normally distributed in the BDF format. Before installing
   such fonts, it is desirable (but not absolutely necessary) to convert the
   font files to the PCF format. This is done by using the command
   "bdftopcf", e.g.

 $ bdftopcf courier12.bdf

   You may then want to compress the resulting PCF font files:

 $ gzip courier12.pcf

   After the fonts have been converted, you should copy all the font files
   that you wish to make available into a arbitrary directory, say
   "/usr/local/share/fonts/bitmap/". You should then create the index file
   "fonts.dir" by running the command "mkfontdir" (please see the
   [23]mkfontdir(1) manual page for more information):

 $ mkdir /usr/local/share/fonts/bitmap/
 $ cp *.pcf.gz /usr/local/share/fonts/bitmap/
 $ mkfontdir /usr/local/share/fonts/bitmap/

   All that remains is to tell the X server about the existence of the new
   font directory; see [24]Setting the server's font path below.

    Installing scalable fonts

   The X11R7.7 server supports scalable fonts in multiple formats, including
   Type 1, TrueType, and OpenType/CFF. (Earlier versions of X11 also included
   support for the Speedo and CID scalable font formats, but that is not
   included in current releases.)

   Installing scalable fonts is very similar to installing bitmap fonts: you
   create a directory with the font files, and run "mkfontdir" to create an
   index file called "fonts.dir".

   There is, however, a big difference: "mkfontdir" cannot automatically
   recognise scalable font files. For that reason, you must first index all
   the font files in a file called "fonts.scale". While this can be done by
   hand, it is best done by using the "mkfontscale" utility.

 $ mkfontscale /usr/local/share/fonts/Type1/
 $ mkfontdir /usr/local/share/fonts/Type1/

   Under some circumstances, it may be necessary to modify the "fonts.scale"
   file generated by mkfontscale; for more information, please see the
   [25]mkfontdir(1) and [26]mkfontscale(1) manual pages and [27]Core fonts
   and internationalisation later in this document.

    CID-keyed fonts

   The CID-keyed font format was designed by Adobe Systems for fonts with
   large character sets. The CID-keyed format is obsolete, as it has been
   superseded by other formats such as OpenType/CFF and support for CID-keyed
   fonts has been removed from X11.

    Setting the server's font path

   The list of directories where the server looks for fonts is known as the
   font path. Informing the server of the existence of a new font directory
   consists of putting it on the font path.

   The font path is an ordered list; if a client's request matches multiple
   fonts, the first one in the font path is the one that gets used. When
   matching fonts, the server makes two passes over the font path: during the
   first pass, it searches for an exact match; during the second, it searches
   for fonts suitable for scaling.

   For best results, scalable fonts should appear in the font path before the
   bitmap fonts; this way, the server will prefer bitmap fonts to scalable
   fonts when an exact match is possible, but will avoid scaling bitmap fonts
   when a scalable font can be used. (The ":unscaled" hack, while still
   supported, should no longer be necessary in X11R7.7.)

   You may check the font path of the running server by typing the command

 $ xset q

      Font path catalogue directories

   You can specify a special kind of font path directory in the form
   catalogue:<dir>. The directory specified after the catalogue: prefix will
   be scanned for symlinks and each symlink destination will be added as a
   local font path entry.

   The symlink can be suffixed by attributes such as 'unscaled', which will
   be passed through to the underlying font path entry. The only exception is
   the newly introduced 'pri' attribute, which will be used for ordering the
   font paths specified by the symlinks.

   An example configuration:

          75dpi:unscaled:pri=20 -> /usr/share/X11/fonts/75dpi
          ghostscript:pri=60 -> /usr/share/fonts/default/ghostscript
          misc:unscaled:pri=10 -> /usr/share/X11/fonts/misc
          type1:pri=40 -> /usr/share/X11/fonts/Type1
          type1:pri=50 -> /usr/share/fonts/default/Type1

   This will add /usr/share/X11/fonts/misc as the first font path entry with
   the attribute unscaled. This is functionally equivalent to setting the
   following font path:

          /usr/share/X11/fonts/misc:unscaled,
          /usr/share/X11/fonts/75dpi:unscaled,
          /usr/share/X11/fonts/Type1,
          /usr/share/fonts/default/Type1,
          /usr/share/fonts/default/ghostscript

      Temporary modification of the font path

   The "xset" utility may be used to modify the font path for the current
   session. The font path is set with the command xset fp; a new element is
   added to the front with xset +fp, and added to the end with xset fp+. For
   example,

 $ xset +fp /usr/local/fonts/Type1
 $ xset fp+ /usr/local/fonts/bitmap

   Conversely, an element may be removed from the front of the font path with
   "xset -fp", and removed from the end with "xset fp-". You may reset the
   font path to its default value with "xset fp default".

   For more information, please consult the [28]xset(1) manual page.

      Permanent modification of the font path

   The default font path (the one used just after server startup or after
   "xset fp default") may be specified in the X server's "xorg.conf" file. It
   is computed by appending all the directories mentioned in the "FontPath"
   entries of the "Files" section in the order in which they appear. If no
   font path is specified in a config file, the server uses a default value
   specified when it was built.

 FontPath "/usr/local/fonts/Type1"
 ...
 FontPath "/usr/local/fonts/bitmap"

   For more information, please consult the [29]xorg.conf(5) manual page.

    Troubleshooting

   If you seem to be unable to use some of the fonts you have installed, the
   first thing to check is that the "fonts.dir" files are correct and that
   they are readable by the server (the X server usually runs as root, beware
   of NFS-mounted font directories). If this doesn't help, it is quite
   possible that you are trying to use a font in a format that is not
   supported by your server.

   X11R7.7 supports the BDF, PCF, SNF, Type 1, TrueType, and OpenType font
   formats. However, not all X11R7.7 servers come with all the font backends
   configured in.

   On most platforms, the X11R7.7 servers no longer uses font backends from
   modules that are loaded at runtime. The built in font support corresponds
   to the functionality formerly provided by these modules:

     * "bitmap": bitmap fonts ("*.bdf", "*.pcf" and "*.snf");

     * "freetype": TrueType fonts ("*.ttf" and "*.ttc"), OpenType fonts
       ("*.otf" and "*.otc") and Type 1 fonts ("*.pfa" and "*.pfb").

                          Fonts included with X11R7.7

  Standard bitmap fonts

   The Sample Implementation of X11 (SI) comes with a large number of bitmap
   fonts, including the "fixed" family, and bitmap versions of Courier,
   Times, Helvetica and some members of the Lucida family.

   In X11R7.7, a number of these fonts are provided in Unicode-encoded font
   files now. At build time, these fonts are split into font files encoded
   according to legacy encodings, a process which allows us to provide the
   standard fonts in a number of regional encodings with no duplication of
   work.

   For example, the font file

 /usr/share/fonts/X11/misc/6x13.bdf

   with XLFD

 -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso10646-1

   is a Unicode-encoded version of the standard "fixed" font with added
   support for the Latin, Greek, Cyrillic, Georgian, Armenian, IPA and other
   scripts plus numerous technical symbols. It contains over 2800 glyphs,
   covering all characters of ISO 8859 parts 1-5, 7-10, 13-15, as well as all
   European IBM and Microsoft code pages, KOI8, WGL4, and the repertoires of
   many other character sets.

   This font is used at build time for generating the font files

 6x13-ISO8859-1.bdf
 6x13-ISO8859-2.bdf
 ...
 6x13-ISO8859-15.bdf
 6x13-KOI8-R.bdf

   with respective XLFDs

 -misc-fixed-medium-r-normal--13-120-75-75-c-60-iso8859-1
 ...
 -misc-fixed-medium-r-normal--13-120-75-75-c-60-iso8859-15
 -misc-fixed-medium-r-normal--13-120-75-75-c-60-koi8-r

   The standard short name "fixed" is normally an alias for

 -misc-fixed-medium-r-normal--13-120-75-75-c-60-iso8859-1

  The ClearlyU Unicode font family

   The ClearlyU family of fonts provides a set of 12 pt, 100 dpi proportional
   fonts with many of the glyphs needed for Unicode text. Together, the fonts
   contain approximately 7500 glyphs.

   The main ClearlyU font has the XLFD

 -mutt-clearlyu-medium-r-normal--17-120-100-100-p-101-iso10646-1

   and resides in the font file

 /usr/share/fonts/X11/misc/cu12.pcf.gz

   Additional ClearlyU fonts include

 -mutt-clearlyu alternate glyphs-medium-r-normal--17-120-100-100-p-91-iso10646-1
 -mutt-clearlyu pua-medium-r-normal--17-120-100-100-p-111-iso10646-1
 -mutt-clearlyu arabic extra-medium-r-normal--17-120-100-100-p-103-fontspecific-0
 -mutt-clearlyu ligature-medium-r-normal--17-120-100-100-p-141-fontspecific-0

   The Alternate Glyphs font contains additional glyph shapes that are needed
   for certain languages. A second alternate glyph font will be provided
   later for cases where a character has more than one commonly used
   alternate shape (e.g. the Urdu heh).

   The PUA font contains extra glyphs that are useful for certain rendering
   purposes.

   The Arabic Extra font contains the glyphs necessary for characters that
   don't have all of their possible shapes encoded in ISO 10646. The glyphs
   are roughly ordered according to the order of the characters in the
   ISO 10646 standard.

   The Ligature font contains ligatures for various scripts that may be
   useful for improved presentation of text.

  Standard scalable fonts

   X11R7.7 includes all the scalable fonts distributed with X11R6.

    Standard Type 1 fonts

   The IBM Courier set of fonts cover ISO 8859-1 and ISO 8859-2 as well as
   Adobe Standard Encoding. These fonts have XLFD

 -adobe-courier-medium-*-*--0-0-0-0-m-0-*-*

   and reside in the font files

 /usr/share/fonts/X11/Type1/cour*.pfa

   The Adobe Utopia set of fonts only cover ISO 8859-1 as well as Adobe
   Standard Encoding. These fonts have XLFD

 -adobe-utopia-*-*-normal--0-0-0-0-p-0-iso8859-1

   and reside in the font files

 /usr/share/fonts/X11/Type1/UT*.pfa

   Finally, X11R7.7 also comes with Type 1 versions of Bitstream Courier and
   Charter. These fonts have XLFD

 -bitstream-courier-*-*-normal--0-0-0-0-m-0-iso8859-1
 -bitstream-charter-*-*-normal--0-0-0-0-p-0-iso8859-1

   and reside in the font files

 /usr/share/fonts/X11/Type1/c*bt_.pfb

  The Bigelow & Holmes Luxi family

   X11R7.7 includes the Luxi family of scalable fonts, in both TrueType and
   Type 1 format. This family consists of the fonts Luxi Serif, with XLFD

 -b&h-luxi serif-medium-*-normal--*-*-*-*-p-*-*-*

   Luxi Sans, with XLFD

 -b&h-luxi sans-medium-*-normal--*-*-*-*-p-*-*-*

   and Luxi Mono, with XLFD

 -b&h-luxi mono-medium-*-normal--*-*-*-*-m-*-*-*

   Each of these fonts comes Roman, oblique, bold and bold oblique variants
   The TrueType version have glyphs covering the basic ASCII Unicode range,
   the Latin 1 range, as well as the Extended Latin range and some additional
   punctuation characters. In particular, these fonts include all the glyphs
   needed for ISO 8859 parts 1, 2, 3, 4, 9, 13 and 15, as well as all the
   glyphs in the Adobe Standard encoding and the Windows 3.1 character set.

   The glyph coverage of the Type 1 versions is somewhat reduced, and only
   covers ISO 8859 parts 1, 2 and 15 as well as the Adobe Standard encoding.

   The Luxi fonts are original designs by Kris Holmes and Charles Bigelow.
   Luxi fonts include seriffed, sans serif, and monospaced styles, in roman
   and oblique, and normal and bold weights. The fonts share stem weight,
   x-height, capital height, ascent and descent, for graphical harmony.

   The character width metrics of Luxi roman and bold fonts match those of
   core fonts bundled with popular operating and window systems.

   The license terms for the Luxi fonts are included in the file
   "COPYRIGHT.BH", as well as in the License document.

   Charles Bigelow and Kris Holmes from Bigelow and Holmes Inc. developed the
   Luxi typeface designs in Ikarus digital format.

   URW++ Design and Development GmbH converted the Ikarus format fonts to
   TrueType and Type1 font programs and implemented the grid-fitting "hints"
   and kerning tables in the Luxi fonts.

   For more information, please contact <[30]design@bigelowandholmes.com> or
   <[31]info@urwpp.de>, or consult [32]the URW++ web site.

   An earlier version of the Luxi fonts was made available under the name
   Lucidux. This name should no longer be used due to trademark
   uncertainties, and all traces of the Lucidux name have been removed from
   X11R7.7.

                             More about core fonts

   This section describes XFree86-created enhancements to the core X11 fonts
   system that were adopted by X.Org.

  Core fonts and internationalisation

   The scalable font backends (Type 1 and TrueType) can automatically
   re-encode fonts to the encoding specified in the XLFD in "fonts.dir". For
   example, a "fonts.dir" file can contain entries for the Type 1 Courier
   font such as

 cour.pfa -adobe-courier-medium-r-normal--0-0-0-0-m-0-iso8859-1
 cour.pfa -adobe-courier-medium-r-normal--0-0-0-0-m-0-iso8859-2

   which will lead to the font being recoded to ISO 8859-1 and ISO 8859-2
   respectively.

    The fontenc layer

   Two of the scalable backends (Type 1 and the FreeType TrueType backend)
   use a common fontenc layer for font re-encoding. This allows these
   backends to share their encoding data, and allows simple configuration of
   new locales independently of font type.

   Please note: the X-TrueType (X-TT) backend is not included in X11R7.7.
   That functionality has been merged into the FreeType backend.

   In the fontenc layer, an encoding is defined by a name (such as
   iso8859-1), possibly a number of aliases (alternate names), and an ordered
   collection of mappings. A mapping defines the way the encoding can be
   mapped into one of the target encodings known to fontenc; currently, these
   consist of Unicode, Adobe glyph names, and arbitrary TrueType "cmap"s.

   A number of encodings are hardwired into fontenc, and are therefore always
   available; the hardcoded encodings cannot easily be redefined. These
   include:

     * iso10646-1: Unicode;

     * iso8859-1: ISO Latin-1 (Western Europe);

     * iso8859-2: ISO Latin-2 (Eastern Europe);

     * iso8859-3: ISO Latin-3 (Southern Europe);

     * iso8859-4: ISO Latin-4 (Northern Europe);

     * iso8859-5: ISO Cyrillic;

     * iso8859-6: ISO Arabic;

     * iso8859-7: ISO Greek;

     * iso8859-8: ISO Hebrew;

     * iso8859-9: ISO Latin-5 (Turkish);

     * iso8859-10: ISO Latin-6 (Nordic);

     * iso8859-15: ISO Latin-9, or Latin-0 (Revised Western-European);

     * koi8-r: KOI8 Russian;

     * koi8-u: KOI8 Ukrainian (see RFC 2319);

     * koi8-ru: KOI8 Russian/Ukrainian;

     * koi8-uni: KOI8 "Unified" (Russian, Ukrainian, and Byelorussian);

     * koi8-e: KOI8 "European," ISO-IR-111, or ECMA-Cyrillic;

     * microsoft-symbol and apple-roman: these are only likely to be useful
       with TrueType symbol fonts.

   Additional encodings can be added by defining encoding files. When a font
   encoding is requested that the fontenc layer doesn't know about, the
   backend checks the directory in which the font file resides (not
   necessarily the directory with fonts.dir!) for a file named
   "encodings.dir". If found, this file is scanned for the requested
   encoding, and the relevant encoding definition file is read in. The
   "mkfontdir" utility, when invoked with the "-e" option followed by the
   name of a directory containing encoding files, can be used to
   automatically build "encodings.dir" files. Please see the [33]mkfontdir(1)
   manual page for more details.

   A number of encoding files for common encodings are included with X11R7.7.
   Information on writing new encoding files can be found in [34]Format of
   encoding directory files and [35]Format of encoding files later in this
   document.

    Backend-specific notes about fontenc

      The FreeType backend

   For TrueType and OpenType fonts, the FreeType backend scans the mappings
   in order. Mappings with a target of PostScript are ignored; mappings with
   a TrueType or Unicode target are checked against all the cmaps in the
   file. The first applicable mapping is used.

   For Type 1 fonts, the FreeType backend first searches for a mapping with a
   target of PostScript. If one is found, it is used. Otherwise, the backend
   searches for a mapping with target Unicode, which is then composed with a
   built-in table mapping codes to glyph names. Note that this table only
   covers part of the Unicode code points that have been assigned names by
   Adobe.

   Specifying an encoding value of adobe-fontspecific for a Type 1 font
   disables the encoding mechanism. This is useful with symbol and
   incorrectly encoded fonts (see [36]Hints about using badly encoded fonts
   below).

   If a suitable mapping is not found, the FreeType backend defaults to
   ISO 8859-1.

    Format of encoding directory files

   In order to use a font in an encoding that the font backend does not know
   about, you need to have an "encodings.dir" file either in the same
   directory as the font file used or in a system-wide location
   ("/usr/share/fonts/X11/encodings/" by default).

   The "encodings.dir" file has a similar format to "fonts.dir". Its first
   line specifies the number of encodings, while every successive line has
   two columns, the name of the encoding, and the name of the encoding file;
   this can be relative to the current directory, or absolute. Every encoding
   name should agree with the encoding name defined in the encoding file. For
   example,

 3
 mulearabic-0 /usr/share/fonts/X11/encodings/mulearabic-0.enc
 mulearabic-1 /usr/share/fonts/X11/encodings/mulearabic-1.enc
 mulearabic-2 /usr/share/fonts/X11/encodings/mulearabic-2.enc

   The name of an encoding must be specified in the encoding file's
   "STARTENCODING" or "ALIAS" line. It is not enough to create an
   "encodings.dir" entry.

   If your platform supports it (it probably does), encoding files may be
   compressed or gzipped.

   The "encoding.dir" files are best maintained by the "mkfontdir" utility.
   Please see the [37]mkfontdir(1) manual page for more information.

    Format of encoding files

   The encoding files are "free form," i.e. any string of whitespace is
   equivalent to a single space. Keywords are parsed in a non-case-sensitive
   manner, meaning that "size", "SIZE", and "SiZE" all parse as the same
   keyword; on the other hand, case is significant in glyph names.

   Numbers can be written in decimal, as in "256", in hexadecimal, as in
   "0x100", or in octal, as in "0400".

   Comments are introduced by a hash sign "#". A "#" may appear at any point
   in a line, and all characters following the "#" are ignored, up to the end
   of the line.

   The encoding file starts with the definition of the name of the encoding,
   and possibly its alternate names (aliases):

 STARTENCODING mulearabic-0
 ALIAS arabic-0

   The name of the encoding and its aliases should be suitable for use in an
   XLFD font name, and therefore contain exactly one dash "-".

   The encoding file may then optionally declare the size of the encoding.
   For a linear encoding (such as ISO 8859-1), the SIZE line specifies the
   maximum code plus one:

 SIZE 0x2B

   For a matrix encoding, it should specify two numbers. The first is the
   number of the last row plus one, the other, the highest column number plus
   one. In the case of "jisx0208.1990-0" (JIS X 0208(1990), double-byte
   encoding, high bit clear), it should be

 SIZE 0x75 0x80

   In the case of a matrix encoding, a "FIRSTINDEX" line may be included to
   specify the minimum glyph index in an encoding. The keyword "FIRSTINDEX"
   is followed by two integers, the minimum row number followed by the
   minimum column number:

 FIRSTINDEX 0x20 0x20

   In the case of a linear encoding, a "FIRSTINDEX" line is not very useful.
   If for some reason however you chose to include on, it should be followed
   by a single integer.

   Note that in most font backends inclusion of a "FIRSTINDEX" line has the
   side effect of disabling default glyph generation, and this keyword should
   therefore be avoided unless absolutely necessary.

   Codes outside the region defined by the "SIZE" and "FIRSTINDEX" lines are
   understood to be undefined. Encodings default to linear encoding with a
   size of 256 (0x100). This means that you must declare the size of all 16
   bit encodings.

   What follows is one or more mapping sections. A mapping section starts
   with a "STARTMAPPING" line stating the target of the mapping. The target
   may be one of:

     * Unicode (ISO 10646):

 STARTMAPPING unicode

     * a given TrueType "cmap":

 STARTMAPPING cmap 3 1

     * PostScript glyph names:

 STARTMAPPING postscript

   Every line in a mapping section maps one from the encoding being defined
   to the target of the mapping. In mappings with a Unicode or TrueType
   mapping, codes are mapped to codes:

 0x21 0x0660
 0x22 0x0661
 ...

   As an abbreviation, it is possible to map a contiguous range of codes in a
   single line. A line consisting of three integers

 <it/start/ <it/end/ <it/target/

   is an abbreviation for the range of lines

 start     target

 start+1   target+1

 ...

 end       target+end-start

   For example, the line

 0x2121 0x215F 0x8140

   is an abbreviation for

 0x2121 0x8140
 0x2122 0x8141
 ...
 0x215F 0x817E

   Codes not listed are assumed to map through the identity (i.e. to the same
   numerical value). In order to override this default mapping, you may
   specify a range of codes to be undefined by using an "UNDEFINE" line:

 UNDEFINE 0x00 0x2A

   or, for a single code,

 UNDEFINE 0x1234

   PostScript mappings are different. Every line in a PostScript mapping maps
   a code to a glyph name

 0x41 A
 0x42 B
 ...

   and codes not explicitly listed are undefined.

   A mapping section ends with an ENDMAPPING line

 ENDMAPPING

   After all the mappings have been defined, the file ends with an
   ENDENCODING line

 ENDENCODING

   In order to make future extensions to the format possible, lines starting
   with an unknown keyword are silently ignored, as are mapping sections with
   an unknown target.

    Using symbol fonts

   Type 1 symbol fonts should be installed using the adobe-fontspecific
   encoding.

   In an ideal world, all TrueType symbol fonts would be installed using one
   of the microsoft-symbol and apple-roman encodings. A number of symbol
   fonts, however, are not marked as such; such fonts should be installed
   using microsoft-cp1252, or, for older fonts, microsoft-win3.1.

   In order to guarantee consistent results (especially between Type 1 and
   TrueType versions of the same font), it is possible to define a special
   encoding for a given font. This has already been done for the ZapfDingbats
   font; see the file "encodings/adobe-dingbats.enc".

    Hints about using badly encoded fonts

   A number of text fonts are incorrectly encoded. Incorrect encoding is
   sometimes done by design, in order to make a font for an exotic script
   appear like an ordinary Western text font on systems which are not easily
   extended with new locale data. It is often the result of the font
   designer's laziness or incompetence; for some reason, most people seem to
   find it easier to invent idiosyncratic glyph names rather than follow the
   Adobe glyph list.

   There are two ways of dealing with such fonts: using them with the
   encoding they were designed for, and creating an ad hoc encoding file.

      Using fonts with the designer's encoding

   In the case of Type 1 fonts, the font designer can specify a default
   encoding; this encoding is requested by using the "adobe-fontspecific"
   encoding in the XLFD name. Sometimes, the font designer omitted to specify
   a reasonable default encoding, in which case you should experiment with
   "adobe-standard", "iso8859-1", "microsoft-cp1252", and "microsoft-win3.1".
   (The encoding "microsoft-symbol" doesn't make sense for Type 1 fonts).

   TrueType fonts do not have a default encoding. However, most TrueType
   fonts are designed with either Microsoft or Apple platforms in mind, so
   one of "microsoft-symbol", "microsoft-cp1252", "microsoft-win3.1", or
   "apple-roman" should yield reasonable results.

      Specifying an ad hoc encoding file

   It is always possible to define an encoding file to put the glyphs in a
   font in any desired order. Again, see the "encodings/adobe-dingbats.enc"
   file to see how this is done.

      Specifying font aliases

   By following the directions above, you will find yourself with a number of
   fonts with unusual names --- with encodings such as "adobe-fontspecific",
   "microsoft-win3.1" etc. In order to use these fonts with standard
   applications, it may be useful to remap them to their proper names.

   This is done by writing a "fonts.alias" file. The format of this file is
   very simple: it consists of a series of lines each mapping an alias name
   to a font name. A "fonts.alias" file might look as follows:

 "-ogonki-alamakota-medium-r-normal--0-0-0-0-p-0-iso8859-2" \
   "-ogonki-alamakota-medium-r-normal--0-0-0-0-p-0-adobe-fontspecific"

   (both XLFD names on a single line). The syntax of the "fonts.alias" file
   is more precisely described in the [38]mkfontdir(1) manual page.

  Additional notes about scalable core fonts

    About the FreeType backend

   The FreeType backend (formerly xfsft) is a backend based on version 2 of
   the FreeType library (see [39]the FreeType web site) and has the X-TT
   functionalities for CJKV support provided by the After X-TT Project (see
   [40]the After X-TT Project web site). The FreeType backend has support for
   the "fontenc" style of internationalisation (see [41]The fontenc layer).
   This backend supports TrueType font files ("*.ttf"), OpenType font files
   ("*.otf"), TrueType Collections ("*.ttc"), OpenType Collections ("*.otc")
   and Type 1 font files ("*.pfa" and "*.pfb").

   In order to access the faces in a TrueType Collection file, the face
   number must be specified in the fonts.dir file before the filename, within
   a pair of colons, or by setting the 'fn' TTCap option. For example,

 :1:mincho.ttc -misc-pmincho-medium-r-normal--0-0-0-0-p-0-jisx0208.1990-0

   refers to face 1 in the "mincho.ttc" TrueType Collection file.

   The new FreeType backend supports the extended "fonts.dir" syntax
   introduced by X-TrueType with a number of options, collectively known as
   "TTCap". A "TTCap" entry follows the general syntax

 option=value:

   and should be specified before the filename. The new FreeType almost
   perfectly supports TTCap options that are compatible with X-TT 1.4. The
   Automatic Italic ("ai"), Double Strike ("ds") and Bounding box Width
   ("bw") options are indispensable in CJKV. For example,

 mincho.ttc -misc-mincho-medium-r-normal--0-0-0-0-c-0-jisx0208.1990-0
 ds=y:mincho.ttc -misc-mincho-bold-r-normal--0-0-0-0-c-0-jisx0208.1990-0
 ai=0.2:mincho.ttc -misc-mincho-medium-i-normal--0-0-0-0-c-0-jisx0208.1990-0
 ds=y:ai=0.2:mincho.ttc -misc-mincho-bold-i-normal--0-0-0-0-c-0-jisx0208.1990-0
 bw=0.5:mincho.ttc -misc-mincho-medium-r-normal--0-0-0-0-c-0-jisx0201.1976-0
 bw=0.5:ds=y:mincho.ttc -misc-mincho-bold-r-normal--0-0-0-0-c-0-jisx0201.1976-0
 bw=0.5:ai=0.2:mincho.ttc -misc-mincho-medium-i-normal--0-0-0-0-c-0-jisx0201.1976-0
 bw=0.5:ds=y:ai=0.2:mincho.ttc -misc-mincho-bold-i-normal--0-0-0-0-c-0-jisx0201.1976-0

   setup the complete combination of jisx0208 and jisx0201 using mincho.ttc
   only. More information on the TTCap syntax is found on [42]the After X-TT
   Project page.

   The FreeType backend uses the fontenc layer in order to support recoding
   of fonts; this was described in [43]The fontenc layer and especially
   [44]The FreeType backend earlier in this document.

    Delayed glyph rasterisation

   When loading a proportional fonts which contain a huge number of glyphs,
   the old FreeType delayed glyph rasterisation until the time at which the
   glyph was first used. The new FreeType (libfreetype-xtt2) has an improved
   "very lazy" metric calculation method to speed up the process when loading
   TrueType or OpenType fonts. Although the X-TT module also has this method,
   the "vl=y" TTCap option must be set if you want to use it. This is the
   default method for FreeType when it loads multi-byte fonts. Even if you
   use a unicode font which has tens of thousands of glyphs, this delay will
   not be worrisome as long as you use the new FreeType backend -- its "very
   lazy" method is super-fast.

   The maximum error of bitmap position using "very lazy" method is 1 pixel,
   and is the same as that of a character-cell spacing. When the X-TT backend
   is used with the "vl=y" option, a chipped bitmap is displayed with certain
   fonts. However, the new FreeType backend has minimal problem with this,
   since it corrects left- and right-side bearings using "italicAngle" in the
   TrueType/OpenType post table, and does automatic correction of bitmap
   positions when rasterisation so that chipped bitmaps are not displayed.
   Nevertheless if you don't want to use the "very lazy" method when using
   multi-bytes fonts, set "vl=n" in the TTCap option to disable it:

 vl=n:luxirr.ttf -b&h-Luxi Serif-medium-r-normal--0-0-0-0-p-0-iso10646-1

   Of course, both backends also support an optimisation for character-cell
   fonts (fonts with all glyph metrics equal, or terminal fonts). A font with
   an XLFD specifying a character-cell spacing "c", as in

 -misc-mincho-medium-r-normal--0-0-0-0-c-0-jisx0208.1990-0

   or

 fs=c:mincho.ttc -misc-mincho-medium-r-normal--0-0-0-0-p-0-jisx0208.1990-0

   will not compute the metric for each glyph, but instead trust the font to
   be a character-cell font. You are encouraged to make use of this
   optimisation when useful, but be warned that not all monospaced fonts are
   character-cell fonts.

                      Appendix: background and terminology

  Characters and glyphs

   A computer text-processing system inputs keystrokes and outputs glyphs,
   small pictures that are assembled on paper or on a computer screen.
   Keystrokes and glyphs do not, in general, coincide: for example, if the
   system does generate ligatures, then to the sequence of two keystrokes
   <f><i> will typically correspond a single glyph. Similarly, if the system
   shapes Arabic glyphs in a vaguely reasonable manner, then multiple
   different glyphs may correspond to a single keystroke.

   The complex transformation rules from keystrokes to glyphs are usually
   factored into two simpler transformations, from keystrokes to characters
   and from characters to glyphs. You may want to think of characters as the
   basic unit of text that is stored e.g. in the buffer of your text editor.
   While the definition of a character is intrinsically application-specific,
   a number of standardised collections of characters have been defined.

   A coded character set is a set of characters together with a mapping from
   integer codes --- known as codepoints --- to characters. Examples of coded
   character sets include US-ASCII, ISO 8859-1, KOI8-R, and JIS X 0208(1990).

   A coded character set need not use 8 bit integers to index characters.
   Many early systems used 6 bit character sets, while 16 bit (or more)
   character sets are necessary for ideographic writing systems.

  Font files, fonts, and XLFD

   Traditionally, typographers speak about typefaces and founts. A typeface
   is a particular style or design, such as Times Italic, while a fount is a
   molten-lead incarnation of a given typeface at a given size.

   Digital fonts come in font files. A font file contains the information
   necessary for generating glyphs of a given typeface, and applications
   using font files may access glyph information in an arbitrary order.

   Digital fonts may consist of bitmap data, in which case they are said to
   be bitmap fonts. They may also consist of a mathematical description of
   glyph shapes, in which case they are said to be scalable fonts. Common
   formats for scalable font files are Type 1 (sometimes incorrectly called
   ATM fonts or PostScript fonts), TrueType and OpenType.

   The glyph data in a digital font needs to be indexed somehow. How this is
   done depends on the font file format. In the case of Type 1 fonts, glyphs
   are identified by glyph names. In the case of TrueType fonts, glyphs are
   indexed by integers corresponding to one of a number of indexing schemes
   (usually Unicode --- see below).

   The X11 core fonts system uses the data in a font file to generate font
   instances, which are collections of glyphs at a given size indexed
   according to a given encoding.

   X11 core font instances are usually specified using a notation known as
   the X Logical Font Description (XLFD). An XLFD starts with a dash "-", and
   consists of fourteen fields separated by dashes, for example:

 -adobe-courier-medium-r-normal--12-120-75-75-m-70-iso8859-1

   Or particular interest are the last two fields "iso8859-1", which specify
   the font instance's encoding.

   A scalable font is specified by an XLFD which contains zeroes instead of
   some fields:

 -adobe-courier-medium-r-normal--0-0-0-0-m-0-iso8859-1

   X11 font instances may also be specified by short name. Unlike an XLFD, a
   short name has no structure and is simply a conventional name for a font
   instance. Two short names are of particular interest, as the server will
   not start if font instances with these names cannot be opened. These are
   "fixed", which specifies the fallback font to use when the requested font
   cannot be opened, and "cursor", which specifies the set of glyphs to be
   used by the mouse pointer.

   Short names are usually implemented as aliases to XLFDs; the standard
   "fixed" and "cursor" aliases are defined in

 /usr/share/font/X11/misc/fonts.alias

  Unicode

   Unicode ([45]http://www.unicode.org) is a coded character set with the
   goal of uniquely identifying all characters for all scripts, current and
   historical. While Unicode was explicitly not designed as a glyph encoding
   scheme, it is often possible to use it as such.

   Unicode is an open character set, meaning that codepoint assignments may
   be added to Unicode at any time (once specified, though, an assignment can
   never be changed). For this reason, a Unicode font will be sparse, meaning
   that it only defines glyphs for a subset of the character registry of
   Unicode.

   The Unicode standard is defined in parallel with the international
   standard ISO 10646. Assignments in the two standards are always
   equivalent, and we often use the terms Unicode and ISO 10646
   interchangeably.

   When used in the X11 core fonts system, Unicode-encoded fonts should have
   the last two fields of their XLFD set to "iso10646-1".

                                   References

   X11R7.7 comes with extensive documentation in the form of manual pages and
   typeset documents. Before installing fonts, you really should read the
   [46]fontconfig(3) and [47]mkfontdir(1) manual pages; other manual pages of
   interest include [48]X(7), [49]Xserver(1), [50]xset(1), [51]Xft(3),
   [52]xlsfonts(1) and [53]showfont(1). In addition, you may want to read the
   X Logical Font Description document by Jim Flowers.

   The [54]comp.fonts FAQ, which is unfortunately no longer being maintained,
   contains a wealth of information about digital fonts.

   Xft and Fontconfig are described on [55]the Fontconfig site.

   The [56]xfsft home page has been superseded by this document, and is now
   obsolete; you may however still find some of the information that it
   contains useful. [57]Joerg Pommnitz' xfsft page is the canonical source
   for the "ttmkfdir" utility, which is the ancestor of mkfontscale.

   [58]The author's software pages might or might not contain related
   scribbles and development versions of software.

   The documentation of X-TrueType is available from [59]the After X-TT
   Project page.

   While the [60]Unicode consortium site may be of interest, you are more
   likely to find what you need in Markus Kuhn's [61]UTF-8 and Unicode FAQ.

   The IETF RFC documents, available from a number of sites throughout the
   world, often provide interesting information about character set issues;
   see for example [62]RFC 373.

References

   Visible links
   1. mailto:jch@freedesktop.org
   2. file:///tmp/xmlto.gCsTr2/fonts.proc#Introduction
   3. file:///tmp/xmlto.gCsTr2/fonts.proc#Two_font_systems
   4. file:///tmp/xmlto.gCsTr2/fonts.proc#Installing_fonts
   5. file:///tmp/xmlto.gCsTr2/fonts.proc#Configuring_Xft
   6. file:///tmp/xmlto.gCsTr2/fonts.proc#Configuring_the_core_X11_fonts_system
   7. file:///tmp/xmlto.gCsTr2/fonts.proc#Fonts_included_with_X11
   8. file:///tmp/xmlto.gCsTr2/fonts.proc#Standard_bitmap_fonts
   9. file:///tmp/xmlto.gCsTr2/fonts.proc#The_ClearlyU_Unicode_font_family
  10. file:///tmp/xmlto.gCsTr2/fonts.proc#Standard_scalable_fonts
  11. file:///tmp/xmlto.gCsTr2/fonts.proc#The_Bigelow_and__Holmes_Luxi_family
  12. file:///tmp/xmlto.gCsTr2/fonts.proc#More_about_core_fonts
  13. file:///tmp/xmlto.gCsTr2/fonts.proc#Core_fonts_and_internationalisation
  14. file:///tmp/xmlto.gCsTr2/fonts.proc#Additional_notes_about_scalable_core_fonts
  15. file:///tmp/xmlto.gCsTr2/fonts.proc#Appendix_background_and_terminology
  16. file:///tmp/xmlto.gCsTr2/fonts.proc#Characters_and_glyphs
  17. file:///tmp/xmlto.gCsTr2/fonts.proc#Font_files_fonts_and_XLFD
  18. file:///tmp/xmlto.gCsTr2/fonts.proc#Unicode
  19. file:///tmp/xmlto.gCsTr2/fonts.proc#References
  20. Installing fonts
	file:///tmp/xmlto.gCsTr2/fonts.proc#Installing_fonts
  21. Appendix: background and terminology
	file:///tmp/xmlto.gCsTr2/fonts.proc#Appendix_background_and_terminology
  22. http://www.fontconfig.org/
  23. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  24. Setting the server's font path
	file:///tmp/xmlto.gCsTr2/fonts.proc#Setting_the_servers_font_path
  25. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  26. file:///tmp/xmlto.gCsTr2/mkfontscale.1.html
  27. Core fonts and internationalisation
	file:///tmp/xmlto.gCsTr2/fonts.proc#Core_fonts_and_internationalisation
  28. file:///tmp/xmlto.gCsTr2/xset.1.html
  29. file:///tmp/xmlto.gCsTr2/xorg.conf.5.html
  30. mailto:design@bigelowandholmes.com
  31. mailto:info@urwpp.de
  32. http://www.urwpp.de/
  33. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  34. Format of encoding directory files
	file:///tmp/xmlto.gCsTr2/fonts.proc#Format_of_encoding_directory_files
  35. Format of encoding files
	file:///tmp/xmlto.gCsTr2/fonts.proc#Format_of_encoding_files
  36. Hints about using badly encoded fonts
	file:///tmp/xmlto.gCsTr2/fonts.proc#Hints_about_using_badly_encoded_fonts
  37. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  38. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  39. http://www.freetype.org/
  40. http://x-tt.sourceforge.jp/
  41. The fontenc layer
	file:///tmp/xmlto.gCsTr2/fonts.proc#The_fontenc_layer
  42. http://x-tt.sourceforge.jp/
  43. The fontenc layer
	file:///tmp/xmlto.gCsTr2/fonts.proc#The_fontenc_layer
  44. The FreeType backend
	file:///tmp/xmlto.gCsTr2/fonts.proc#The_FreeType_backend
  45. http://www.unicode.org/
  46. file:///tmp/xmlto.gCsTr2/fontconfig.3.html
  47. file:///tmp/xmlto.gCsTr2/mkfontdir.1.html
  48. file:///tmp/xmlto.gCsTr2/X.7.html
  49. file:///tmp/xmlto.gCsTr2/Xserver.1.html
  50. file:///tmp/xmlto.gCsTr2/xset.1.html
  51. file:///tmp/xmlto.gCsTr2/Xft.3.html
  52. file:///tmp/xmlto.gCsTr2/xlsfonts.1.html
  53. file:///tmp/xmlto.gCsTr2/showfont.1.html
  54. http://www.faqs.org/faqs/by-newsgroup/comp/comp.fonts.html
  55. http://www.fontconfig.org/
  56. http://www.dcs.ed.ac.uk/home/jec/programs/xfsft/
  57. http://www.joerg-pommnitz.de/TrueType/xfsft.html
  58. http://www.pps.jussieu.fr/~jch/software/
  59. http://x-tt.sourceforge.jp/
  60. http://www.unicode.org/
  61. http://www.cl.cam.ac.uk/~mgk25/unicode.html
  62. https://datatracker.ietf.org/doc/rfc373/
