














           [1mX Logical Font Description Conventions[0m

                        [1mVersion 1.5[0m

                   [1mX Consortium Standard[0m

                 [1mX Version 11, Release 6.4[0m






                        Jim Flowers
               Digital Equipment Corporation






            Version 1.5 edited by Stephen Gildea
                     X Consortium, Inc.












































[4mX[24m [4mWindow[24m [4mSystem[24m 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.






























































[1m1.  Introduction[0m

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 [4mX[24m [4mWindow[24m [4mSystem[24m [4mProtocol[24m, 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 de-
sirable for the most common queries to be accomplished without the over-
head  of  opening  each font and inspecting font properties, by means of
simple requests.  For example, if a user selected a  Helvetica  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 family.

This  document  gives a standard logical font description (hereafter re-
ferred 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 the XLFD also provides for a standard set
of key 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 un-
known 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.

[1m2.  Requirements and Goals[0m

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  en-
     codings

+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

+o    Supports arbitrarily complex font matching or substitution




                                    [1m1[0m





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+o    Is extensible

[1m2.1.  Provide Unique and Descriptive Font Names[0m

It should be possible to have font names that are long  enough  and  de-
scriptive  enough to have a reasonable probability of being unique with-
out inventing a new registration organization.  Resolution and  size-de-
pendent  font masters, multivendor font libraries, and so on must be an-
ticipated 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.

[1m2.2.  Support Multiple Font Vendors and Character Sets[0m

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 re-
quirements.

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.

[1m2.3.  Support Scalable and Polymorphic Fonts[0m

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.

[1m2.4.  Support Transformations and Subsetting of Fonts[0m

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.

[1m2.5.  Be Independent of X Server and Operating or File System  Implemen-[0m
[1mtations[0m

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
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



                                    [1m2[0m





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name.  This algorithm should be reversible (exactly how this translation
is done is implementation dependent).

[1m2.6.  Support Arbitrarily Complex Font Matching and Substitution[0m

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.

[1m2.7.  Be Extensible[0m

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.

[1m3.  X Logical Font Description[0m

XLFD  is divided into two basic components: the which gives all font in-
formation needed to uniquely identify a font in X protocol requests (for
example,  and  so  on)  and a variable list of optional which describe a
font in more detail.

The is used in font queries and is returned as data in certain X  proto-
col  requests.   It  is also specified as the data value for the item in
the X Consortium Character  Bitmap  Distribution  Format  Standard  (BDF
V2.1).

The  are  supplied  on  a font-by-font basis and are returned as data in
certain X protocol requests as part of the data  structure.   The  names
and  associated  data values for each of the may also appear as items of
the [1mSTARTPROPERTIES[22m...[1mENDPROPERTIES [22mlist in the BDF V2.1 specification.

[1m3.1.  FontName[0m

Each is logically composed of two strings: a prefix that is followed  by
a The uses the ISO 8859-1 encoding.  The 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 syntax and semantics.

All  font  names that conform to this specification are to use a prefix,
which is defined to be the string "-" (HYPHEN).   All  prefixes  of  the
form:  +[4mversion[24m-, where the specified 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 appending new fields to the  current  structure,
each  delimited  by  the  existing field delimiter.  The availability of
other prefixes or fonts that support other registries is  server  imple-
mentation dependent.

In  the X protocol specification, the is required to be a string; hence,
numeric field values are represented in the name as string  equivalents.
All  fields  are also defined as numeric property values are represented



                                    [1m3[0m





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as signed or unsigned integers, as appropriate.

[1m3.1.1.  FontName Syntax[0m

The is a structured, parsable string (of type STRING8) whose Backus-Naur
Form syntax description is as follows:

rw(1.5i) lw(3.75i).
T{  FontName  ::=  T}   T{ XFontNameRegistry XFontNameSuffix | PrivFont-
NameRegistry PrivFontNameSuffix T} T{ XFontNameRegistry ::= T}   T{ XFN-
Delim  | XFNExtPrefix Version XFNDelim T} T{ XFontNameSuffix ::= T}   T{
FOUNDRY XFNDelim FAMILY_NAME XFNDelim WEIGHT_NAME XFNDelim SLANT  XFNDe-
lim  SETWIDTH_NAME XFNDelim ADD_ STYLE_NAME XFNDelim PIXEL_SIZE XFNDelim
POINT_SIZE XFNDelim RESOLUTION_X XFNDelim RESOLUTION_Y XFNDelim  SPACING
XFNDelim AVERAGE_WIDTH XFNDelim CHARSET_REGISTRY XFNDelim CHARSET_ENCOD-
ING T} T{ Version ::= T}   T{ STRING8 - the XLFD version that defines an
extension  to  the font name syntax (for example, "1.4") T} XFNExtPrefix
::=    OCTET - "+" (PLUS) XFNDelim ::=   OCTET - "-" (HYPHEN)  T{  Priv-
FontNameRegistry ::= T}   T{ STRING8 - other than those strings reserved
by XLFD T} 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
must  have  no more than 255 characters.  It is recommended that clients
construct font name query patterns by explicitly including all field de-
limiters  to avoid unexpected results.  Note that SPACE is a valid char-
acter of a field; for example, the string "ITC Avant Garde Gothic" might
be a FAMILY_NAME.

[1m3.1.2.  FontName Field Definitions[0m

This section discusses the

+o    FOUNDRY field

+o    FAMILY_NAME field





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+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

[1m3.1.2.1.  FOUNDRY Field[0m

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 field according to the  registration  procedures  de-
fined by the Consortium.

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.


[1m3.1.2.2.  FAMILY_NAME Field[0m

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  re-
quired.  This name must be human-understandable and suitable for presen-
tation to a font user to identify the typeface family.




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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

[1m3.1.2.3.  WEIGHT_NAME Field[0m

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 ty-
pographic 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
calculated weight, respectively.

[1m3.1.2.4.  SLANT Field[0m

SLANT is a code-string that indicates the overall posture of  the  type-
face design used in the font.  The encoding is as follows:

lw(.5i) lw(1.25i) lw(3.5i).  _
[1mCode English Translation Description[0m
[1m_[0m
"R"  Roman     Upright  design  "I"  Italic    T{ Italic design, slanted
clockwise from the vertical T} "O"  Oblique   T{  Obliqued  upright  de-
sign,  slanted  clockwise  from  the  vertical T} "RI" Reverse Italic T{
Italic  design,  slanted   counterclockwise   from   the   vertical   T}



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lw(.5i) lw(1.25i) lw(3.5i).  _
[1mCode English Translation Description[0m
[1m_[0m
"RO" Reverse  Oblique    T{  Obliqued  upright  design, slanted counter-
clockwise from the vertical T}  "OT" Other     Other  numeric   Polymor-
phic    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.

[1m3.1.2.5.  SETWIDTH_NAME Field[0m

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 ap-
plications 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

[1m3.1.2.6.  ADD_STYLE_NAME Field[0m

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





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+o    Sans Serif

+o    Informal

+o    Decorated

[1m3.1.2.7.  PIXEL_SIZE Field[0m

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.

[1m3.1.2.8.  POINT_SIZE Field[0m

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.

[1m3.1.2.9.  RESOLUTION_X and RESOLUTION_Y Fields[0m

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 re-
quired 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 be-
cause 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



                                    [1m8[0m





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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.

[1m3.1.2.10.  SPACING Field[0m

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:

lw(.5i) lw(1.25i) lw(3.5i).  _
[1mCode English Translation Description[0m
[1m_[0m
"P"  Proportional   T{ A font whose logical character  widths  vary  for
each  glyph.   Note that no other restrictions are placed on the metrics
of a proportional font.  T} "M"  Monospaced     T{ A font whose  logical
character  widths are constant (that is, every glyph in the font has the
same logical width).  No other restrictions are placed on the metrics of
a  monospaced font.  T} "C"  CharCell  T{ 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-bottom  to
form text lines).  By definition, all glyphs have the same logical char-
acter width, and no glyphs have "ink" outside  of  the  character  cell.
There  is  no  kerning  (that is, on a per-character basis with positive
metrics: 0 <= left-bearing <= right-bearing <= width; with negative met-
rics: width <= left-bearing <= right-bearing <= zero).  Also, the verti-
cal extents of the font do not exceed the vertical spacing (that is,  on
a  per-character  basis:  ascent  <= font-ascent and descent <= font-de-
scent).  The cell height = font-descent + font-ascent, and the  width  =
AVERAGE_WIDTH.  T}
_


[1m3.1.2.11.  AVERAGE_WIDTH Field[0m

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).

[1m3.1.2.12.  CHARSET_REGISTRY and CHARSET_ENCODING Fields[0m

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.



                                    [1m9[0m





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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
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  en-
vironments  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:

rw(1.5i) lw(3.75i).
CharsetRegistry  ::= T{ StdCharsetRegistryName | PrivCharsetRegistryName
T} CharsetEncoding ::= T{ StdCharsetEncodingName |  PrivCharsetEncoding-
Name  T}  StdCharsetRegistryName ::=    T{ StdOrganizationId StdNumber |
StdOrganizationId  StdNumber   Dot   Year   T}   PrivCharsetRegistryName
::=   OrganizationId     STRING8     StdCharsetEncodingName    ::=    T{
STRING8-numeric part number of referenced standard T}  PrivCharsetEncod-
ingName  ::= STRING8  StdOrganizationId ::=    T{ STRING8-the registered
name or acronym of the referenced  standard  organization  T}  StdNumber
::=  STRING8-referenced    standard    number   OrganizationId   ::=  T{
STRING8-the registered name  or  acronym  of  the  organization  T}  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 su-
perset 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

rw(1.5i) l.  Subset ::=     LeftBracket RangeList RightBracket RangeList
::=  Range | Range Space RangeList Range ::= Number | Number  Underscore
Number Number ::=     "0x" HexNumber | DecNumber 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



                                   [1m10[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


::=     "["  (LEFT SQUARE BRACKET) RightBracket ::=    "]" (RIGHT SQUARE
BRACKET) Space ::= " " (SPACE) Underscore ::= "_" (LOW LINE)


Each Range specifies characters that are to be part of  the  subset  in-
cluded  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 number.  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.

[1m3.1.3.  Examples[0m

The  following  examples of font names are derived from the screen fonts
shipped with the X Consortium distribution.

lw(1.45i) lw(4.45i).  _
[1mFont X FontName[0m
[1m_[0m
[1m75-dpi Fonts[0m
T{    Charter    12    pt    T}   T{    -Bitstream-Charter-Medium-R-Nor-
mal--12-120-75-75-P-68-ISO8859-1  T} T{ Charter Bold 12 pt T}   T{ -Bit-
stream-Charter-Bold-R-Normal--12-120-75-75-P-76-ISO8859-1 T} T{  Charter
Bold     Italic    12    pt    T}   T{    -Bitstream-Charter-Bold-I-Nor-
mal--12-120-75-75-P-75-ISO8859-1 T} T{  Charter  Italic  12  pt  T}   T{
-Bitstream-Charter-Medium-I-Normal--12-120-75-75-P-66-ISO8859-1       T}
Courier 8 pt   -Adobe-Courier-Medium-R-Normal--8-80-75-75-M-50-ISO8859-1
Courier               10               pt   -Adobe-Courier-Medium-R-Nor-
mal--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  T{  Courier  Bold  10  pt
T}   T{  -Adobe-Courier-Bold-R-Normal--10-100-75-75-M-60-ISO8859-1 T} T{
Courier  Bold   Oblique   10   pt   T}   T{   -Adobe-Courier-Bold-O-Nor-
mal--10-100-75-75-M-60-ISO8859-1  T}  T{  Courier  Oblique 10 pt T}   T{
-Adobe-Courier-Medium-O-Normal--10-100-75-75-M-60-ISO8859-1 T}
[1m100-dpi Fonts[0m
T{     Symbol     10     pt     T}   T{      -Adobe-Symbol-Medium-R-Nor-
mal--14-100-100-100-P-85-Adobe-FONTSPECIFIC  T}  T{ Symbol 14 pt T}   T{
-Adobe-Symbol-Medium-R-Normal--20-140-100-100-P-107-Adobe-FONTSPECIFIC
T}    T{    Symbol    18    pt    T}   T{    -Adobe-Symbol-Medium-R-Nor-
mal--25-180-100-100-P-142-Adobe-FONTSPECIFIC T} T{ Symbol 24 pt  T}   T{
-Adobe-Symbol-Medium-R-Normal--34-240-100-100-P-191-Adobe-FONTSPECIFIC
T}   T{   Times   Bold   10    pt    T}   T{    -Adobe-Times-Bold-R-Nor-
mal--14-100-100-100-P-76-ISO8859-1 T} T{ Times Bold Italic 10 pt T}   T{
-Adobe-Times-Bold-I-Normal--14-100-100-100-P-77-ISO8859-1  T}  T{  Times
Italic        10       pt       T}   T{       -Adobe-Times-Medium-I-Nor-
mal--14-100-100-100-P-73-ISO8859-1 T}  T{  Times  Roman  10  pt  T}   T{
-Adobe-Times-Medium-R-Normal--14-100-100-100-P-74-ISO8859-1 T} _



                                   [1m11[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1m3.2.  Font Properties[0m

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:

rw(1.5i) lw(3.75i).
Properties  ::= OptFontPropList  OptFontPropList  ::= NULL | OptFontProp
OptFontPropList OptFontProp ::=     PrivateFontProp | XFontProp Private-
FontProp  ::=     T{  STRING8  |  Underscore  OrganizationId  Underscore
STRING8 T} XFontProp ::=  T{ FOUNDRY | FAMILY_NAME | WEIGHT_NAME | SLANT
|  SETWIDTH_NAME  |  ADD_STYLE_NAME  | PIXEL_SIZE | POINT_SIZE | RESOLU-
TION_X | RESOLUTION_Y | SPACING |  AVERAGE_WIDTH  |  CHARSET_REGISTRY  |
CHARSET_ENCODING  |  QUAD_WIDTH  | RESOLUTION | MIN_SPACE | NORM_SPACE |
MAX_SPACE | END_SPACE | SUPERSCRIPT_X | SUPERSCRIPT_Y  |  SUBSCRIPT_X  |
SUBSCRIPT_Y  |  UNDERLINE_POSITION | UNDERLINE_THICKNESS | STRIKEOUT_AS-
CENT | STRIKEOUT_DESCENT | ITALIC_ANGLE | X_HEIGHT | WEIGHT |  FACE_NAME
| FULL_NAME | FONT | COPYRIGHT | AVG_CAPITAL_WIDTH | AVG_LOWERCASE_WIDTH
| RELATIVE_SETWIDTH | RELATIVE_WEIGHT | CAP_HEIGHT | SUPERSCRIPT_ SIZE |
FIGURE_WIDTH  | SUBSCRIPT_SIZE | SMALL_CAP_SIZE | NOTICE | DESTINATION |
FONT_TYPE  |  FONT_VERSION  |  RASTERIZER_NAME  |  RASTERIZER_VERSION  |
RAW_ASCENT | RAW_DESCENT | RAW_* | AXIS_NAMES | AXIS_LIMITS | AXIS_TYPES
T}  Underscore   ::= OCTET-"_"   (LOW   LINE)   OrganizationId   ::=  T{
STRING8-the registered name of the organization T}


[1m3.2.1.  FOUNDRY[0m

FOUNDRY is as defined in the except that the property type is ATOM.

FOUNDRY  cannot  be  calculated  or  defaulted if not supplied as a font
property.







                                   [1m12[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1m3.2.2.  FAMILY_NAME[0m

FAMILY_NAME is as defined in the except that the property type is ATOM.

FAMILY_NAME cannot be calculated or defaulted if not supplied as a  font
property.

[1m3.2.3.  WEIGHT_NAME[0m

WEIGHT_NAME is as defined in the except that the property type is ATOM.

WEIGHT_NAME can be defaulted if not supplied as a font property, as fol-
lows:


     if (WEIGHT_NAME undefined) then
        WEIGHT_NAME = ATOM("Medium")


[1m3.2.4.  SLANT[0m

SLANT is as defined in the 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")


[1m3.2.5.  SETWIDTH_NAME[0m

SETWIDTH_NAME is as defined in the 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")


[1m3.2.6.  ADD_STYLE_NAME[0m

ADD_STYLE_NAME is as defined in the except that  the  property  type  is
ATOM.

ADD_STYLE_NAME  can  be defaulted if not supplied as a font property, as
follows:







                                   [1m13[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


     if (ADD_STYLE_NAME undefined) then
        ADD_STYLE_NAME = ATOM("")


[1m3.2.7.  PIXEL_SIZE[0m

PIXEL_SIZE is as defined in the except that the property type is INT32.

X clients requiring pixel values for the various typographic fixed  spa-
ces (em space, en space, and thin space) can use the following algorithm
for computing these values from other properties specified for a font:


     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 [4ma[24m up or down to the next integer.  This rounding is done  according
to  X  = FLOOR ([4ma[24m + 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,  ac-
cording to the following algorithm:


     DeciPointsPerInch = 722.7
     if (PIXEL_SIZE undefined) then
        PIXEL_SIZE = ROUND ((RESOLUTION_Y * POINT_SIZE) / DeciPointsPerInch)


[1m3.2.8.  POINT_SIZE[0m

POINT_SIZE is as defined in the 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.

[1m3.2.9.  RESOLUTION_X[0m

RESOLUTION_X is as defined in the  except  that  the  property  type  is
CARD32.




                                   [1m14[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


RESOLUTION_X cannot be calculated or approximated.

[1m3.2.10.  RESOLUTION_Y[0m

RESOLUTION_Y  is  as  defined  in  the  except that the property type is
CARD32.

RESOLUTION_X cannot be calculated or approximated.

[1m3.2.11.  SPACING[0m

SPACING is as defined in the 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

[1m3.2.12.  AVERAGE_WIDTH[0m

AVERAGE_WIDTH  is  as  defined  in  the except that the property type is
INT32.

AVERAGE_WIDTH can be calculated if not provided as a font property,  ac-
cording 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


[1m3.2.13.  CHARSET_REGISTRY[0m

CHARSET_REGISTRY is as defined in the except that the property  type  is
ATOM.

CHARSET_REGISTRY cannot be defaulted if not supplied as a font property.

[1m3.2.14.  CHARSET_ENCODING[0m

CHARSET_ENCODING  is  as defined in the except that the property type is
ATOM.




                                   [1m15[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


CHARSET_ENCODING cannot be defaulted if not supplied as a font property.

[1m3.2.15.  MIN_SPACE[0m

MIN_SPACE is an integer value (of type INT32) that gives the recommended
minimum word-space value to be used with this font.

MIN_SPACE  can  be  approximated if not provided as a font property, ac-
cording to the following algorithm:


     if (MIN_SPACE undefined) then
        MIN_SPACE = ROUND(0.75 * NORM_SPACE)


[1m3.2.16.  NORM_SPACE[0m

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, ac-
cording 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)


[1m3.2.17.  MAX_SPACE[0m

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, ac-
cording to the following algorithm:


     if (MAX_SPACE undefined) then
        MAX_SPACE = ROUND(1.5 * NORM_SPACE)


[1m3.2.18.  END_SPACE[0m

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, ac-
cording to the following algorithm:






                                   [1m16[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


     if (END_SPACE undefined) then
        END_SPACE = NORM_SPACE


[1m3.2.19.  AVG_CAPITAL_WIDTH[0m

AVG_CAPITAL_WIDTH is an integer value (of type INT32) that gives the un-
weighted arithmetic mean of the absolute value of the width of each cap-
ital 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


[1m3.2.20.  AVG_LOWERCASE_WIDTH[0m

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


[1m3.2.21.  QUAD_WIDTH[0m

QUAD_WIDTH  is  an integer typographic metric (of type INT32) that gives
the width of a quad (em) space.  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



                                   [1m17[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


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 character width font properties (AVERAGE_WIDTH,
AVG_CAPITAL_WIDTH or AVG_LOWERCASE_WIDTH).

[1m3.2.22.  FIGURE_WIDTH[0m

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, ac-
cording 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


[1m3.2.23.  SUPERSCRIPT_X[0m

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.

[1m3.2.24.  SUPERSCRIPT_Y[0m

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:




                                   [1m18[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


     if (SUPERSCRIPT_Y undefined) then
        SUPERSCRIPT_Y = ROUND(0.40 * CAP_HEIGHT)


[1m3.2.25.  SUBSCRIPT_X[0m

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, ac-
cording 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)


[1m3.2.26.  SUBSCRIPT_Y[0m

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, ac-
cording to the following algorithm:


     if (SUBSCRIPT_Y undefined) then
        SUBSCRIPT_Y = ROUND(0.40 * CAP_HEIGHT)


[1m3.2.27.  SUPERSCRIPT_SIZE[0m

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 ac-
cording 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)






                                   [1m19[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1m3.2.28.  SUBSCRIPT_SIZE[0m

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)


[1m3.2.29.  SMALL_CAP_SIZE[0m

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))


[1m3.2.30.  UNDERLINE_POSITION[0m

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 [4mmaximum[24m [4mdescent[24m is the maximum descent  (below  the  baseline)  in
pixels of any glyph in the font.

[1m3.2.31.  UNDERLINE_THICKNESS[0m

UNDERLINE_THICKNESS  is  an integer value (of type INT32) that gives the
recommended underline thickness, in pixels.




                                   [1m20[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


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


[1m3.2.32.  STRIKEOUT_ASCENT[0m

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 [4mmaximum[24m [4mascent[24m is the maximum ascent (above the baseline) in  pix-
els of any glyph in the font.

[1m3.2.33.  STRIKEOUT_DESCENT[0m

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 [4mmaximum[24m [4mdescent[24m is the maximum descent  (below  the  baseline)  in
pixels of any glyph in the font.

[1m3.2.34.  ITALIC_ANGLE[0m

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, ac-
cording to the following algorithm:




                                   [1m21[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


     if (ITALIC_ANGLE undefined) then
        ITALIC_ANGLE = (90 * 64)


[1m3.2.35.  CAP_HEIGHT[0m

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 de-
signed 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,  ac-
cording 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


[1m3.2.36.  X_HEIGHT[0m

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








                                   [1m22[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1m3.2.37.  RELATIVE_SETWIDTH[0m

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:

lw(.5i) lw(1i) lw(2.75i).  _
[1mCode English Translation Description[0m
[1m_[0m
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, Nor-
mal, Regular, ...  60   SemiExpanded   SemiExpanded,  DemiExpanded,  ...
70   Expanded  80   ExtraExpanded  ExtraExpanded, Wide, ...  90   Ultra-
Expanded  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.

[1m3.2.38.  RELATIVE_WEIGHT[0m

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.

RELATIVE_WEIGHT ranges from 10 to 90 or is 0 if  undefined  or  unknown.
The following reference values are defined:




                                   [1m23[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


lw(.5i) lw(1i) lw(3.75i).  _
[1mCode English Translation Description[0m
[1m_[0m
0    Undefined Undefined or unknown 10   UltraLight     The lowest ratio
of stem width to height 20   ExtraLight 30   Light  40   SemiLight Semi-
Light, Book, ...  50   Medium    Medium, Normal, Regular,...  60   Semi-
Bold  SemiBold,  DemiBold,  ...    70   Bold   80   ExtraBold ExtraBold,
Heavy,  ...   90   UltraBold T{ UltraBold, Black, ..., the highest ratio
of stem width to height T}
_


RELATIVE_WEIGHT can be defaulted if not provided as a font property, ac-
cording 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.

[1m3.2.39.  WEIGHT[0m

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.

[1m3.2.40.  RESOLUTION[0m

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.  As
independent horizontal and vertical design resolution components are re-
quired to accommodate displays with nonsquare aspect ratios, the use  of
this font property has been deprecated, and independent RESOLUTION_X and
RESOLUTION_Y font name fields/properties have been defined (see sections



                                   [1m24[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


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.

[1m3.2.41.  FONT[0m

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.

[1m3.2.42.  FACE_NAME[0m

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.

[1m3.2.43.  FULL_NAME[0m

FULL_NAME  is  the  same as FACE_NAME.  Its use is deprecated, but it is
found on some old fonts.

[1m3.2.44.  COPYRIGHT[0m

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.

[1m3.2.45.  NOTICE[0m

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.





                                   [1m25[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


NOTICE cannot be calculated or approximated if not provided  as  a  font
property.

[1m3.2.46.  DESTINATION[0m

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:

lw(.5i) lw(1i) lw(3.75i).  _
[1mCode English Translation Description[0m
[1m_[0m
0    WYSIWYG   T{ The font is optimized to match the typographic  design
and  metrics  of  an equivalent printer font.  T} 1    Video text     T{
The font is optimized for screen legibility and readability.  T}
_



[1m3.2.47.  FONT_TYPE[0m

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.

Predefined values are as follows:

l lw(5i).  _
[1mValue     When applicable[0m
[1m_[0m
"Bitmap"  T{ Hand-tuned bitmap fonts.  Some attempt has been made to op-
timize the visual appearance of the font for the requested size and res-
olution.  T} "Prebuilt"     T{ All bitmap format fonts  that  cannot  be
described  as "Bitmap", that is, hand-tuned.  For example, a bitmap for-
mat font that was generated mechanically using a scalable  font  raster-
izer  would  be  considered  "Prebuilt", not "Bitmap".  T} "Type 1"  Any
Type 1 font.  "TrueType"     Any TrueType  font.   "Speedo"  Any  Speedo
font.  "F3" Any F3 font.
_





                                   [1m26[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


Other values may be registered with the X Consortium.

[1m3.2.48.  FONT_VERSION[0m

FONT_VERSION  is  a  human-understandable string (of type ATOM) that de-
scribes the formal or informal version of the font.   [1mNone  [22mis  a  valid
value.

[1m3.2.49.  RASTERIZER_NAME[0m

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:

rw(1.5i) lw(3.75i).  RasterizerName ::=  OrganizationId Space Rasterizer
OrganizationId ::=   T{ STRING8--the X Registry ORGANIZATION name of the
rasterizer  implementor  or  maintainer.  T} Rasterizer ::= T{ the case-
sensitive, human-understandable product name of the  rasterizer.   Words
within  this  name  should  be  separated  by  a single SPACE.  T} Space
::= OCTET-" " (SPACE)


Examples:
          X Consortium Bit Scaler
          X Consortium Type 1 Rasterizer
          X Consortium Speedo Rasterizer
          Adobe Type Manager
          Sun TypeScaler

If RASTERIZER_NAME is not defined, or is [1mNone[22m, no  rasterization  opera-
tion has been applied to the FONT_TYPE.

[1m3.2.50.  RASTERIZER_VERSION[0m

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.

[1m3.2.51.  RAW_ASCENT[0m

For a font with a transformation matrix, RAW_ASCENT is the  font  ascent
in 1000 pixel metrics (see section 4.1).

[1m3.2.52.  RAW_DESCENT[0m

For a font with a transformation matrix, RAW_DESCENT is the font descent
in 1000 pixel metrics (see section 4.1).







                                   [1m27[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1m3.2.53.  RAW_*[0m

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.

[1m3.2.54.  AXIS_NAMES[0m

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).

[1m3.2.55.  AXIS_LIMITS[0m

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).

[1m3.2.56.  AXIS_TYPES[0m

AXIS_TYPES  is like AXIS_NAMES, but can be registered as having specific
semantics (see section 6).

[1m3.3.  Built-in Font Property Atoms[0m

The following font property atom definitions were predefined in the ini-
tial version of the core protocol:

l l.  _
[1mFont Property/Atom Name  Property Type[0m
[1m_[0m
MIN_SPACE INT32 NORM_SPACE     INT32 MAX_SPACE INT32 END_SPACE INT32 SU-
PERSCRIPT_X  INT32   SUPERSCRIPT_Y  INT32   SUBSCRIPT_X    INT32    SUB-
SCRIPT_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 - dep-
recated FAMILY_NAME    ATOM DEFAULT_CHAR   CARD32
_


[1m4.  Matrix Transformations[0m

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.




                                   [1m28[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


The BNF for a matrix transformation string is as follows:

rw(1.5i)  l.   MatrixString  ::=    T{  LeftBracket  OptionalSpace Float
Space Float Space Float Space Float OptionalSpace  RightBracket  T}  Op-
tionalSpace  ::=    ""  |  Space  Space  ::= SpaceChar | SpaceChar Space
Float ::=  Mantissa | Mantissa Exponent  Mantissa  ::=   Sign  Number  |
Number Sign ::=  Plus | Tilde Number ::=     Integer | Integer Dot Inte-
ger | Dot Integer Integer ::=    Digit | Digit Integer Digit  ::= "0"  |
"1"  |  "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" Exponent ::=   "e"
SignedInteger | "E" SignedInteger SignedInteger ::=   Sign Integer | In-
teger 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

c    c    c    c    c.     [    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.

[1m4.1.  Metrics and Font Properties[0m

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:




                                   [1m29[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


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.

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  re-
quested 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 at-
tributes 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.

[1m5.  Scalable Fonts[0m

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:

[1mWell-formed XLFD pattern[0m

     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.





                                   [1m30[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


[1mScalable font name[0m

     A well-formed XLFD pattern containing no wildcards  and  containing
     the  digit  "0"  in  the  PIXEL_SIZE, POINT_SIZE, and AVERAGE_WIDTH
     fields.

[1mScalable fields[0m

     The XLFD fields PIXEL_SIZE, POINT_SIZE, RESOLUTION_X, RESOLUTION_Y,
     and AVERAGE_WIDTH.

[1mDerived instance[0m

     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.

[1mGlobal list[0m

     The  list of names that would be returned by an X server for a pro-
     tocol request on the pattern "*" if there were no protocol restric-
     tions 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 in-
cluded 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  in-
stances in the global list is recommended and sufficient.

The  X  protocol  request  on a scalable font name returns a font corre-
sponding to an implementation-dependent derived instance  of  that  font
name.




                                   [1m31[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


The X protocol request on a well-formed XLFD pattern returns the follow-
ing.  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 instance, re-
move  the font name from the list.  Now take the modified list, and per-
form a simple pattern match against the pattern argument.   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 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


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 pat-
tern  match  against  the global list.  X servers are permitted, but not
required, to use a more sophisticated matching algorithm.

[1m6.  Polymorphic Fonts[0m

Fonts that can be varied in ways  other  than  size  or  resolution  are
called  [4mpolymorphic[24m [4mfonts.[24m  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



                                   [1m32[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


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.

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.



                                   [1m33[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


     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
     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 se-
mantics.

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 [4mnormal[24m or [4mmedium[24m 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 [1mBadName [22merror, treat
the value as if it were the closest legal value, or extrapolate  to  try
to accommodate the value.

[1m7.  Affected Elements of Xlib and the X Protocol[0m

The following X protocol requests must support the XLFD conventions:

+o    - for the name argument





                                   [1m34[0m





[1mX Logical Font Description Conventions                  X11, Release 6.4[0m


+o    - for the pattern argument

+o    - for the pattern argument

In  addition, the following Xlib functions must support the XLFD conven-
tions:

+o    - for the name argument

+o    - for the pattern argument

+o    - for the name argument

+o    - for the pattern argument

[1m8.  BDF Conformance[0m

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.

[1m8.1.  XLFD Conformance Requirements[0m

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 [1mFONT [22mconforms to the syntax and semantic
     definition of a XLFD string.

+o    The begins with the X prefix: "-".

+o    All XLFD fields are defined.

+o    Any  FontProperties  provided  conform in name and semantics to the
     XLFD definitions.

A simple method of testing for conformance would entail  verifying  that
the 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 follows the defini-
tion of a private property.

[1m8.2.  FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR[0m

FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR  are  provided  in  the  BDF
specification  as  properties that are moved to the by the BDF font com-
piler in generating the X  server-specific  binary  font  encoding.   If
present, these properties shall comply with the following semantic defi-
nitions.





                                   [1m35[0m





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[1m8.2.1.  FONT_ASCENT[0m

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 [4mn[24m is at [X,Y], then the origin of the
next line [4mm[24m [4m=[24m [4mn[24m [4m+[24m [4m1[24m (allowing for a possible font change)  is  [X,  Y  +
FONT_DESCENTn + FONT_ASCENTm].

FONT_ASCENT  can be approximated if not provided as a font property, ac-
cording 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.

[1m8.2.2.  FONT_DESCENT[0m

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 [4mn[24m is at [X,Y], then the  origin  of  the
next  line  [4mm[24m  [4m=[24m  [4mn+1[24m  (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, ac-
cording 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.

[1m8.2.3.  DEFAULT_CHAR[0m

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 DE-
FAULT_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.





                                   [1m36[0m









                           [1mTable of Contents[0m


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 Im-
plementations  . . . . . . . . . . . . . . . . . . . . . . . . . . .   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  . . . . . . . . . . . . . . . . .   4
3.1.2.1. FOUNDRY Field . . . . . . . . . . . . . . . . . . . . . . .   5
3.1.2.2. FAMILY_NAME Field . . . . . . . . . . . . . . . . . . . . .   5
3.1.2.3. WEIGHT_NAME Field . . . . . . . . . . . . . . . . . . . . .   6
3.1.2.4. SLANT Field . . . . . . . . . . . . . . . . . . . . . . . .   6
3.1.2.5. SETWIDTH_NAME Field . . . . . . . . . . . . . . . . . . . .   7
3.1.2.6. ADD_STYLE_NAME Field  . . . . . . . . . . . . . . . . . . .   7
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  . . . . . . . . . . .   8
3.1.2.10. SPACING Field  . . . . . . . . . . . . . . . . . . . . . .   9
3.1.2.11. AVERAGE_WIDTH Field  . . . . . . . . . . . . . . . . . . .   9
3.1.2.12. CHARSET_REGISTRY and CHARSET_ENCODING Fields . . . . . . .   9
3.1.3. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
3.2. Font Properties . . . . . . . . . . . . . . . . . . . . . . . .  12
3.2.1. FOUNDRY . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
3.2.2. FAMILY_NAME . . . . . . . . . . . . . . . . . . . . . . . . .  13
3.2.3. WEIGHT_NAME . . . . . . . . . . . . . . . . . . . . . . . . .  13
3.2.4. SLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
3.2.5. SETWIDTH_NAME . . . . . . . . . . . . . . . . . . . . . . . .  13
3.2.6. ADD_STYLE_NAME  . . . . . . . . . . . . . . . . . . . . . . .  13
3.2.7. PIXEL_SIZE  . . . . . . . . . . . . . . . . . . . . . . . . .  14
3.2.8. POINT_SIZE  . . . . . . . . . . . . . . . . . . . . . . . . .  14
3.2.9. RESOLUTION_X  . . . . . . . . . . . . . . . . . . . . . . . .  14
3.2.10. RESOLUTION_Y . . . . . . . . . . . . . . . . . . . . . . . .  15
3.2.11. SPACING  . . . . . . . . . . . . . . . . . . . . . . . . . .  15
3.2.12. AVERAGE_WIDTH  . . . . . . . . . . . . . . . . . . . . . . .  15
3.2.13. CHARSET_REGISTRY . . . . . . . . . . . . . . . . . . . . . .  15
3.2.14. CHARSET_ENCODING . . . . . . . . . . . . . . . . . . . . . .  15
3.2.15. MIN_SPACE  . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.2.16. NORM_SPACE . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.2.17. MAX_SPACE  . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.2.18. END_SPACE  . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.2.19. AVG_CAPITAL_WIDTH  . . . . . . . . . . . . . . . . . . . . .  17
3.2.20. AVG_LOWERCASE_WIDTH  . . . . . . . . . . . . . . . . . . . .  17
3.2.21. QUAD_WIDTH . . . . . . . . . . . . . . . . . . . . . . . . .  17



                                    [1mi[0m





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3.2.22. FIGURE_WIDTH . . . . . . . . . . . . . . . . . . . . . . . .  18
3.2.23. SUPERSCRIPT_X  . . . . . . . . . . . . . . . . . . . . . . .  18
3.2.24. SUPERSCRIPT_Y  . . . . . . . . . . . . . . . . . . . . . . .  18
3.2.25. SUBSCRIPT_X  . . . . . . . . . . . . . . . . . . . . . . . .  19
3.2.26. SUBSCRIPT_Y  . . . . . . . . . . . . . . . . . . . . . . . .  19
3.2.27. SUPERSCRIPT_SIZE . . . . . . . . . . . . . . . . . . . . . .  19
3.2.28. SUBSCRIPT_SIZE . . . . . . . . . . . . . . . . . . . . . . .  20
3.2.29. SMALL_CAP_SIZE . . . . . . . . . . . . . . . . . . . . . . .  20
3.2.30. UNDERLINE_POSITION . . . . . . . . . . . . . . . . . . . . .  20
3.2.31. UNDERLINE_THICKNESS  . . . . . . . . . . . . . . . . . . . .  20
3.2.32. STRIKEOUT_ASCENT . . . . . . . . . . . . . . . . . . . . . .  21
3.2.33. STRIKEOUT_DESCENT  . . . . . . . . . . . . . . . . . . . . .  21
3.2.34. ITALIC_ANGLE . . . . . . . . . . . . . . . . . . . . . . . .  21
3.2.35. CAP_HEIGHT . . . . . . . . . . . . . . . . . . . . . . . . .  22
3.2.36. X_HEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . .  22
3.2.37. RELATIVE_SETWIDTH  . . . . . . . . . . . . . . . . . . . . .  23
3.2.38. RELATIVE_WEIGHT  . . . . . . . . . . . . . . . . . . . . . .  23
3.2.39. WEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
3.2.40. RESOLUTION . . . . . . . . . . . . . . . . . . . . . . . . .  24
3.2.41. FONT . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.2.42. FACE_NAME  . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.2.43. FULL_NAME  . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.2.44. COPYRIGHT  . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.2.45. NOTICE . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.2.46. DESTINATION  . . . . . . . . . . . . . . . . . . . . . . . .  26
3.2.47. FONT_TYPE  . . . . . . . . . . . . . . . . . . . . . . . . .  26
3.2.48. FONT_VERSION . . . . . . . . . . . . . . . . . . . . . . . .  27
3.2.49. RASTERIZER_NAME  . . . . . . . . . . . . . . . . . . . . . .  27
3.2.50. RASTERIZER_VERSION . . . . . . . . . . . . . . . . . . . . .  27
3.2.51. RAW_ASCENT . . . . . . . . . . . . . . . . . . . . . . . . .  27
3.2.52. RAW_DESCENT  . . . . . . . . . . . . . . . . . . . . . . . .  27
3.2.53. RAW_*  . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.2.54. AXIS_NAMES . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.2.55. AXIS_LIMITS  . . . . . . . . . . . . . . . . . . . . . . . .  28
3.2.56. AXIS_TYPES . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.3. Built-in Font Property Atoms  . . . . . . . . . . . . . . . . .  28
4. Matrix Transformations  . . . . . . . . . . . . . . . . . . . . .  28
4.1. Metrics and Font Properties . . . . . . . . . . . . . . . . . .  29
5. Scalable Fonts  . . . . . . . . . . . . . . . . . . . . . . . . .  30
6. Polymorphic Fonts . . . . . . . . . . . . . . . . . . . . . . . .  32
7. Affected Elements of Xlib and the X Protocol  . . . . . . . . . .  34
8. BDF Conformance . . . . . . . . . . . . . . . . . . . . . . . . .  35
8.1. XLFD Conformance Requirements . . . . . . . . . . . . . . . . .  35
8.2. FONT_ASCENT, FONT_DESCENT, and DEFAULT_CHAR . . . . . . . . . .  35
8.2.1. FONT_ASCENT . . . . . . . . . . . . . . . . . . . . . . . . .  36
8.2.2. FONT_DESCENT  . . . . . . . . . . . . . . . . . . . . . . . .  36
8.2.3. DEFAULT_CHAR  . . . . . . . . . . . . . . . . . . . . . . . .  36










                                   [1mii[0m


