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groff_char(7)          Miscellaneous Information Manual          groff_char(7)


Name

       groff_char - GNU roff special character and glyph repertoire


Description

       The GNU roff typesetting system has a large glyph repertoire suitable
       for production of varied literary, professional, technical, and
       mathematical documents.  groff works with characters; an output device
       renders glyphs.  groff's input character set is restricted to that
       defined by the standards ISO Latin-1 (ISO 8859-1) and CCSID "code page"
       1047 (an EBCDIC arrangement of Latin-1).  For ease of document
       maintenance in UTF-8 environments, it is advisable to use only the
       Unicode basic Latin code points, a subset of all of the foregoing
       historically referred to as US-ASCII, which has only 94 visible,
       printable code points.  In groff, these are termed ordinary characters.
       Often, many more are desired in output.

       AT&T troff in the 1970s faced a similar problem: the available
       typesetter's glyph repertoire differed from that of the computers that
       controlled it.  troff's solution was a form of escape sequence known as
       a special character to access several dozen additional glyphs available
       in the fonts prepared for mounting in the phototypesetter.  These
       glyphs were mapped onto a two-character name space for a degree of
       mnemonic convenience; for example, the escape sequence \(aa encoded an
       acute accent and \(sc a section sign.

       groff has lifted historical roff limitations on special character name
       lengths, but recognizes and retains compatibility with the historical
       names.  groff expands the lexicon of glyphs available by name and
       permits users to define their own special character escape sequences
       with the char request.  Special character names are groff identifiers;
       see section "Identifiers" in groff(7).  Our discussion uses the terms
       "glyph name" and "special character name" interchangeably; we assume no
       character translations or redefinitions.

       This document lists all of the glyph names predefined by groff's font
       description files and presents the systematic notation by which it
       enables access to arbitrary Unicode code points and construction of
       composite glyphs.  Glyphs listed may be unavailable, or may vary in
       appearance, depending on the output device and font chosen when the
       page was formatted.  This page was rendered for device ascii using font
       0.

       A few escape sequences that are not groff special characters also
       produce glyphs; these exist for syntactical or historical reasons.  \',
       \`, \-, and \_ are translated on input to the special character escape
       sequences \[aa], \[ga], \[-], and \[ul], respectively.  Others include
       \\, \. (backslash-dot), and \e; see groff(7).  A small number of
       special characters represent glyphs that are not encoded in Unicode;
       examples include the baseline rule \[ru] and the Bell System logo
       \[bs].

       In groff, you can test output device support for any character
       (ordinary or special) with the conditional expression operator "c".
              .ie c \[bs] \{Welcome to the \[bs] Bell System;
              did you get the Wehrmacht helmet or the Death Star?\}
              .el No Bell System logo.

       For brevity in the remainder of this document, we shall refer to
       systems conforming to the ISO 646:1991 IRV, ISO 8859, or ISO 10646
       ("Unicode") character encoding standards as "ISO" systems, and those
       employing IBM code page 1047 as "EBCDIC" systems.  That said, EBCDIC
       systems that support groff are known to also support UTF-8.

       While groff accepts eight-bit encoded input, not all such code points
       are valid as input.  On ISO platforms, character codes 0, 11, 13-31,
       and 128-159 are invalid.  (This is all C0 and C1 controls except for
       SOH through LF [Control+A to Control+J], and FF [Control+L].)  On
       EBCDIC platforms, 0, 8-9, 11, 13-20, 23-31, and 48-63 are invalid.
       Some of these code points are used by groff for internal purposes,
       which is one reason it does not support UTF-8 natively.

   Fundamental character set
       The ordinary characters catalogued above, plus the space, tab, newline,
       and leader (Control+A), form the fundamental character set for groff
       input; anything in the language, even over one million code points in
       Unicode, can be expressed using it.  On ISO systems, code points in the
       range 33-126 comprise a common set of printable glyphs in all of the
       aforementioned ISO character encoding standards.  It is this character
       set and (with some noteworthy exceptions) the corresponding glyph
       repertoire for which AT&T troff was implemented.  On EBCDIC systems,
       printable characters are in the range 66-201 and 203-254; those without
       counterparts in the ISO range 33-126 are discussed in the next
       subsection.

       All of the following characters map to glyphs as you would expect.

             +----------------------------------------------------------+
             |! # $ % & ( ) * + , . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @ |
             |A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ ] _ |
             |a b c d e f g h i j k l m n o p q r s t u v w x y z { | } |
             +----------------------------------------------------------+
       The remaining ordinary characters surprise computing professionals and
       others intimately familiar with the ISO character encodings.  The
       developers of AT&T troff chose mappings for them that would be useful
       for typesetting technical literature in a broad range of scientific
       disciplines: Bell Labs used the system for preparation of AT&T's patent
       filings with the U.S. government.  Further, the prevailing character
       encoding standard in the 1970s, USAS X3.4-1968 ("ASCII"), deliberately
       supported semantic ambiguity at some code points, and outright
       substitution at several others, to suit the localization demands of
       various national standards bodies.

       The table below presents the seven exceptional code points with their
       typical keycap engravings, their glyph mappings and semantics in roff
       systems, and the escape sequences producing the Unicode basic Latin
       character they replace.  The first, the neutral double quote, is a
       partial exception because it does represent itself, but since the roff
       language also uses it to quote macro arguments, groff supports a
       special character escape sequence as an alternative form so that the
       glyph can be easily included in macro arguments without requiring the
       user to master the quoting rules that AT&T troff required in that
       context.  (Some requests, like ds, also treat " non-literally.)
       Furthermore, not all of the special character escape sequences are
       portable to AT&T troff and all of its descendants; these groff
       extensions are presented using its special character form \[], whereas
       portable special character escape sequences are shown in the
       traditional \( form.  \- and \e are portable to all known troffs.  \e
       means "the glyph of the current escape character"; it therefore can
       produce unexpected output if the ec request is used.  On devices with a
       limited glyph repertoire, glyphs in the "keycap" and "appearance"
       columns on the same row of the table may look identical; except for the
       neutral double quote, this will not be the case on more-capable
       devices.  Review your document using as many different output devices
       as possible.

        +-------------------------------------------------------------------+
        |Keycap   Appearance and meaning    Special character and meaning   |
        +-------------------------------------------------------------------+
        |"        " neutral double quote    \[dq] neutral double quote      |
        |'        ' closing single quote    \[aq] neutral apostrophe        |
        |-        - hyphen                  \- or \[-] minus sign/Unix dash |
        |\        (escape character)        \e or \[rs] reverse solidus     |
        |^        <?> modifier circumflex   \(ha circumflex/caret/"hat"     |
        |`        ` opening single quote    \(ga grave accent               |
        |~        ~ modifier tilde          \(ti tilde                      |
        +-------------------------------------------------------------------+
       The hyphen-minus is a particularly unfortunate case of overloading.
       Its awkward name in ISO 8859 and later standards reflects the many
       distinguishable purposes to which it had already been put by the 1980s,
       including a hyphen, a minus sign, and (alone or in repetition) dashes
       of varying widths.  For best results in roff systems, use the "-"
       character in input outside an escape sequence only to mean a hyphen, as
       in the phrase "long-term".  For a minus sign in running text or a Unix
       command-line option dash, use \- (or \[-] in groff if you find it helps
       the clarity of the source document).  (Another minus sign, for use in
       mathematical equations, is available as \[mi]).  AT&T troff supported
       em-dashes as \(em, as does groff.

       The special character escape sequence for the apostrophe as a neutral
       single quote is typically needed only in technical content; typing
       words like "can't" and "Anne's" in a natural way will render correctly,
       because in ordinary prose an apostrophe is typeset either as a closing
       single quotation mark or as a neutral single quote, depending on the
       capabilities of the output device.  By contrast, special character
       escape sequences should be used for quotation marks unless portability
       to limited or historical troff implementations is necessary; on those
       systems, the input convention is to pair the grave accent with the
       apostrophe for single quotes, and to double both characters for double
       quotes.  AT&T troff defined no special characters for quotation marks
       or the apostrophe.  Repeated single quotes (``thus'') will be visually
       distinguishable from double quotes ("thus") on terminal devices, and
       perhaps on others (depending on the font selected).

          +----------------------------------------------------------------+
          |AT&T troff input          recommended groff input               |
          +----------------------------------------------------------------+
          |A Winter's Tale           A Winter's Tale                       |
          |`U.K. outer quotes'       \[oq]U.K. outer quotes\[cq]           |
          |`U.K. ``inner'' quotes'   \[oq]U.K. \[lq]inner\[rq] quotes\[cq] |
          |``U.S. outer quotes''     \[lq]U.S. outer quotes\[rq]           |
          |``U.S. `inner' quotes''   \[lq]U.S. \[oq]inner\[cq] quotes\[rq] |
          +----------------------------------------------------------------+
       If you frequently require quotation marks in your document, see if the
       macro package you're using supplies strings or macros to facilitate
       quotation, or define them yourself (except in man pages).

       Using Unicode basic Latin characters to compose boxes and lines is ill-
       advised.  roff systems have special characters for drawing horizontal
       and vertical lines; see subsection "Rules and lines" below.
       Preprocessors like tbl(1) and pic(1) draw boxes and will produce the
       best possible output for the device, falling back to basic Latin glyphs
       only when necessary.

   Eight-bit encodings and Latin-1 supplement
       ISO 646 is a seven-bit code encoding 128 code points; eight-bit codes
       are twice the size.  ISO 8859-1 and code page 1047 allocated the
       additional space to what Unicode calls "C1 controls" (control
       characters) and the "Latin-1 supplement".  The C1 controls are neither
       printable nor usable as groff input.

       Two Latin-1 supplement characters are handled specially on input.
       troff never produces them as output.

       NBSP   encodes a no-break space; it is mapped to \~, the adjustable
              non-breaking space escape sequence.

       SHY    encodes a soft hyphen; it is mapped to \%, the hyphenation
              control escape sequence.

       The remaining characters in the Latin-1 supplement represent
       themselves.  Although they can be specified directly with the keyboard
       on systems configured to use Latin-1 as the character encoding, it is
       more portable, both to other roff systems and to UTF-8 environments, to
       use their special character escape sequences, shown below.  The glyph
       descriptions we use are non-standard in some cases, for brevity.

       !            \[r!] inverted exclamation mark     N    \[~N] N tilde
       c            \[ct] cent sign                     O    \[`O] O grave
       L            \[Po] pound sign                    O    \['O] O acute
       x            \[Cs] currency sign                 O    \[^O] O circumflex
       Y            \[Ye] yen sign                      O    \[~O] O tilde
       |            \[bb] broken bar                    O    \[:O] O dieresis
       <section>    \[sc] section sign                  x    \[mu] multiplication sign
       "            \[ad] dieresis accent               O    \[/O] O slash
       (C)          \[co] copyright sign                U    \[`U] U grave
       a            \[Of] feminine ordinal indicator    U    \['U] U acute
       <<           \[Fo] left double chevron           U    \[^U] U circumflex
       ~            \[no] logical not                   U    \[:U] U dieresis
       (R)          \[rg] registered sign               Y    \['Y] Y acute
       -            \[a-] macron accent                 Th   \[TP] uppercase thorn
       <degree>     \[de] degree sign                   ss   \[ss] lowercase sharp s
       +-           \[+-] plus-minus                    a    \[`a] a grave
       ^2           \[S2] superscript two               a    \['a] a acute
       ^3           \[S3] superscript three             a    \[^a] a circumflex
       '            \[aa] acute accent                  a    \[~a] a tilde
       <micro>      \[mc] micro sign                    a    \[:a] a dieresis
       <paragraph>  \[ps] pilcrow sign                  a    \[oa] a ring
       .            \[pc] centered period               ae   \[ae] ae ligature
       ,            \[ac] cedilla accent                c    \[,c] c cedilla
       ^1           \[S1] superscript one               e    \[`e] e grave
       o            \[Om] masculine ordinal indicator   e    \['e] e acute
       >>           \[Fc] right double chevron          e    \[^e] e circumflex
       1/4          \[14] one quarter symbol            e    \[:e] e dieresis
       1/2          \[12] one half symbol               i    \[`i] i grave
       3/4          \[34] three quarters symbol         i    \['i] e acute
       ?            \[r?] inverted question mark        i    \[^i] i circumflex
       A            \[`A] A grave                       i    \[:i] i dieresis
       A            \['A] A acute                       dh   \[Sd] lowercase eth
       A            \[^A] A circumflex                  n    \[~n] n tilde
       A            \[~A] A tilde                       o    \[`o] o grave
       A            \[:A] A dieresis                    o    \['o] o acute
       A            \[oA] A ring                        o    \[^o] o circumflex
       AE           \[AE] AE ligature                   o    \[~o] o tilde
       C            \[,C] C cedilla                     o    \[:o] o dieresis
       E            \[`E] E grave                       /    \[di] division sign
       E            \['E] E acute                       o    \[/o] o slash
       E            \[^E] E circumflex                  u    \[`u] u grave
       E            \[:E] E dieresis                    u    \['u] u acute
       I            \[`I] I grave                       u    \[^u] u circumflex
       I            \['I] I acute                       u    \[:u] u dieresis
       I            \[^I] I circumflex                  y    \['y] y acute
       I            \[:I] I dieresis                    th   \[Tp] lowercase thorn
       Dh           \[-D] uppercase eth                 y    \[:y] y dieresis

   Special character escape forms
       Glyphs that lack a character code in the basic Latin repertoire to
       directly represent them are entered by one of several special character
       escape forms.  Such glyphs can be simple or composite, and accessed
       either by name or numerically by code point.  Code points and combining
       properties are determined by character encoding standards, whereas
       glyph names as used here originated in AT&T troff special character
       escape sequences.  Predefined glyph names use only characters in the
       basic Latin repertoire.

       \(gl   is a special character escape sequence for the glyph with the
              two-character name gl.  This is the original syntax form
              supported by AT&T troff.  The acute accent, \(aa, is an example.

       \C'glyph-name'
              is a special character escape sequence for glyph-name, which can
              be of arbitrary length.  The delimiter, shown here as a neutral
              apostrophe, can be any character not occurring in glyph-name.
              This syntax form was introduced in later versions of AT&T
              device-independent troff.  The foregoing acute accent example
              can be expressed as \C'aa'.

       \[glyph-name]
              is a special character escape sequence for glyph-name, which can
              be of arbitrary length but must not contain a closing square
              bracket "]".  (No glyph names predefined by groff employ "]".)
              The foregoing acute accent example can be expressed in groff as
              \[aa].

       \C'c' and \[c] are not synonyms for the ordinary character "c", but
       request the special character named "\c".  For example, "\[a]" is not
       "a", but rather a special character with the internal glyph name (used
       in font description files and diagnostic messages) \a, which is
       typically undefined.  The only such glyph name groff predefines is the
       minus sign, which can therefore be accessed as \C'-' or \[-].

       \[base-char composite-1 composite-2 ... composite-n]
              is a composite glyph.  Glyphs like a lowercase "e" with an acute
              accent, as in the word "caf", can be expressed as \[e aa].  See
              subsection "Accents" below for a table of combining glyph names.

       Unicode encodes far more characters than groff has glyph names for;
       special character escape forms based on numerical code points enable
       access to any of them.  Frequently used glyphs or glyph combinations
       can be stored in strings, and new glyph names can be created ad hoc
       with the char request; see groff(7).

       \[unnnn[n[n]]]
              is a Unicode numeric special character escape sequence.  Any
              Unicode code point can be accessed with four to six hexadecimal
              digits, with hexadecimal letters accepted in uppercase form
              only.  Thus, \[u02DA] accesses the (spacing) ring accent,
              producing "o".

       Unicode code points can be composed as well; when they are, GNU troff
       requires NFD (Normalization Form D), where all Unicode glyphs are
       maximally decomposed.  (Exception: precomposed characters in the
       Latin-1 supplement described above are also accepted.  Do not count on
       this exception remaining in a future GNU troff that accepts UTF-8 input
       directly.)  Thus, GNU troff accepts "caf\['e]", "caf\[e aa]", and
       "caf\[u0065_0301]", as ways to input "cafe".  (Due to its legacy 8-bit
       encoding compatibility, at present it also accepts "caf\[u00E9]" on ISO
       Latin-1 systems.)

       \[ubase-char[_combining-component]...]
              constructs a composite glyph from Unicode numeric special
              character escape sequences.  The code points of the base glyph
              and the combining components are each expressed in hexadecimal,
              with an underscore (_) separating each component.  Thus,
              \[u006E_0303] produces "".

       \[charnnn]
              expresses an eight-bit code point where nnn is the code point of
              the character, a decimal number between 0 and 255 without
              leading zeroes.  This legacy numeric special character escape
              sequence is used to map characters onto glyphs via the trin
              request in macro files loaded by grotty(1).


Glyph tables

       In this section, groff's glyph name repertoire is presented in tabular
       form.  The meanings of the columns are as follows.

       Output  shows the glyph as it appears on the device used to render this
               document; although it can have a notably different shape on
               other devices (and is subject to user-directed translation and
               replacement), groff attempts reasonable equivalency on all
               output devices.

       Input   shows the groff character (ordinary or special) that normally
               produces the glyph.  Some code points have multiple glyph
               names.

       Unicode is the code point notation for the glyph or combining glyph
               sequence as described in subsection "Special character escape
               forms" above.  It corresponds to the standard notation for
               Unicode short identifiers such that groff's unnnn is equivalent
               to Unicode's U+nnnn.

       Notes   describes the glyph, elucidating the mnemonic value of the
               glyph name where possible.

               A plus sign "+" indicates that the glyph name appears in the
               AT&T troff user's manual, CSTR #54 (1992 revision).  When using
               the AT&T special character syntax \(xx, widespread portability
               can be expected from such names.

               Entries marked with "***" denote glyphs used for mathematical
               purposes.  On typesetting devices, such glyphs are typically
               drawn from a special font (see groff_font(5)).  Often, such
               glyphs lack bold or italic style forms or have metrics that
               look incongruous in ordinary prose.  A few which are not
               uncommon in running text have "text variants", which should
               work better in that context.  Conversely, a handful of glyphs
               that are normally drawn from a text font may be required in
               mathematical equations.  Both sets of exceptions are noted in
               the tables where they appear ("Logical symbols" and
               "Mathematical symbols").

   Basic Latin
       Apart from basic Latin characters with special mappings, described in
       subsection "Fundamental character set" above, a few others in that
       range have special character glyph names.  These were defined for ease
       of input on non-U.S. keyboards lacking keycaps for them, or for
       symmetry with other special character glyph names serving a similar
       purpose.

       The vertical bar is overloaded; the \[ba] and \[or] escape sequences
       may render differently.  See subsection "Mathematical symbols" below
       for special variants of the plus, minus, and equals signs normally
       drawn from this range.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       "        \[dq]   u0022     neutral double quote
       #        \[sh]   u0023     number sign
       $        \[Do]   u0024     dollar sign
       '        \[aq]   u0027     apostrophe, neutral single quote
       /        \[sl]   u002F     slash, solidus +
       @        \[at]   u0040     at sign
       [        \[lB]   u005B     left square bracket
       \        \[rs]   u005C     reverse solidus
       ]        \[rB]   u005D     right square bracket
       ^        \[ha]   u005E     circumflex, caret, "hat"
       {        \[lC]   u007B     left brace
       |        |       u007C     bar
       |        \[ba]   u007C     bar
       |        \[or]   u007C     bitwise or +
       }        \[rC]   u007D     right brace
       ~        \[ti]   u007E     tilde

   Supplementary Latin letters
       Historically, \[ss] could be considered a ligature of "sz".  An
       uppercase form is available as \[u1E9E], but in the German language it
       is of specialized use; ss does not normally uppercase-transform to it,
       but rather to "SS".  "Lowercase f with hook" is also used as a function
       symbol; see subsection "Mathematical symbols" below.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       Dh       \[-D]   u00D0     uppercase eth
       dh       \[Sd]   u00F0     lowercase eth
       Th       \[TP]   u00DE     uppercase thorn
       th       \[Tp]   u00FE     lowercase thorn
       ss       \[ss]   u00DF     lowercase sharp s
       i        \[.i]   u0131     i without tittle
       j        \[.j]   u0237     j without tittle
       f        \[Fn]   u0192     lowercase f with hook, function
       L        \[/L]   u0141     L with stroke
       l        \[/l]   u0142     l with stroke
       O        \[/O]   u00D8     O with stroke
       o        \[/o]   u00F8     o with stroke

   Ligatures and digraphs

       Output   Input   Unicode           Notes
       ------------------------------------------------------------------------
       ff       \[ff]   u0066_0066        ff ligature +
       fi       \[fi]   u0066_0069        fi ligature +
       fl       \[fl]   u0066_006C        fl ligature +
       ffi      \[Fi]   u0066_0066_0069   ffi ligature +
       ffl      \[Fl]   u0066_0066_006C   ffl ligature +
       AE       \[AE]   u00C6             AE ligature
       ae       \[ae]   u00E6             ae ligature
       OE       \[OE]   u0152             OE ligature
       oe       \[oe]   u0153             oe ligature
       IJ       \[IJ]   u0132             IJ digraph
       ij       \[ij]   u0133             ij digraph

   Accents
       Normally, the formatting of a special character advances the drawing
       position as an ordinary character does.  groff's composite request
       designates a special character as combining.  The composite.tmac macro
       file, loaded automatically by the default troffrc, maps the following
       special characters to the combining characters shown below.  The non-
       combining code point in parentheses is used when the special character
       occurs in isolation (compare "caf\[e aa]" and "caf\[aa]e").

       Output   Input   Unicode         Notes
       ------------------------------------------------------------------------
       "        \[a"]   u030B (u02DD)   double acute accent
       -        \[a-]   u0304 (u00AF)   macron accent
       .        \[a.]   u0307 (u02D9)   dot accent
       ^        \[a^]   u0302 (u005E)   circumflex accent
       '        \[aa]   u0301 (u00B4)   acute accent +
       `        \[ga]   u0300 (u0060)   grave accent +
       `        \[ab]   u0306 (u02D8)   breve accent
       ,        \[ac]   u0327 (u00B8)   cedilla accent
       "        \[ad]   u0308 (u00A8)   dieresis accent
       v        \[ah]   u030C (u02C7)   caron accent
       o        \[ao]   u030A (u02DA)   ring accent
       ~        \[a~]   u0303 (u007E)   tilde accent
       ,        \[ho]   u0328 (u02DB)   hook accent

   Accented characters
       All of these glyphs can be composed using combining glyph names as
       described in subsection "Special character escape forms" above; the
       names below are short aliases for convenience.

       Output   Input   Unicode      Notes
       ------------------------------------------------------------------------
       A        \['A]   u0041_0301   A acute
                \['C]   u0043_0301   C acute
       E        \['E]   u0045_0301   E acute
       I        \['I]   u0049_0301   I acute
       O        \['O]   u004F_0301   O acute
       U        \['U]   u0055_0301   U acute
       Y        \['Y]   u0059_0301   Y acute
       a        \['a]   u0061_0301   a acute
                \['c]   u0063_0301   c acute
       e        \['e]   u0065_0301   e acute
       i        \['i]   u0069_0301   i acute
       o        \['o]   u006F_0301   o acute
       u        \['u]   u0075_0301   u acute
       y        \['y]   u0079_0301   y acute

       A        \[:A]   u0041_0308   A dieresis
       E        \[:E]   u0045_0308   E dieresis
       I        \[:I]   u0049_0308   I dieresis
       O        \[:O]   u004F_0308   O dieresis
       U        \[:U]   u0055_0308   U dieresis
                \[:Y]   u0059_0308   Y dieresis
       a        \[:a]   u0061_0308   a dieresis
       e        \[:e]   u0065_0308   e dieresis
       i        \[:i]   u0069_0308   i dieresis
       o        \[:o]   u006F_0308   o dieresis
       u        \[:u]   u0075_0308   u dieresis
       y        \[:y]   u0079_0308   y dieresis

       A        \[^A]   u0041_0302   A circumflex
       E        \[^E]   u0045_0302   E circumflex
       I        \[^I]   u0049_0302   I circumflex
       O        \[^O]   u004F_0302   O circumflex
       U        \[^U]   u0055_0302   U circumflex
       a        \[^a]   u0061_0302   a circumflex
       e        \[^e]   u0065_0302   e circumflex
       i        \[^i]   u0069_0302   i circumflex
       o        \[^o]   u006F_0302   o circumflex
       u        \[^u]   u0075_0302   u circumflex

       A        \[`A]   u0041_0300   A grave
       E        \[`E]   u0045_0300   E grave
       I        \[`I]   u0049_0300   I grave
       O        \[`O]   u004F_0300   O grave
       U        \[`U]   u0055_0300   U grave
       a        \[`a]   u0061_0300   a grave
       e        \[`e]   u0065_0300   e grave
       i        \[`i]   u0069_0300   i grave
       o        \[`o]   u006F_0300   o grave
       u        \[`u]   u0075_0300   u grave

       A        \[~A]   u0041_0303   A tilde
       N        \[~N]   u004E_0303   N tilde
       O        \[~O]   u004F_0303   O tilde
       a        \[~a]   u0061_0303   a tilde
       n        \[~n]   u006E_0303   n tilde
       o        \[~o]   u006F_0303   o tilde

                \[vS]   u0053_030C   S caron
                \[vs]   u0073_030C   s caron
                \[vZ]   u005A_030C   Z caron
                \[vz]   u007A_030C   z caron

       C        \[,C]   u0043_0327   C cedilla
       c        \[,c]   u0063_0327   c cedilla

       A        \[oA]   u0041_030A   A ring
       a        \[oa]   u0061_030A   a ring

   Quotation marks
       The neutral double quote, often useful when documenting programming
       languages, is also available as a special character for convenient
       embedding in macro arguments; see subsection "Fundamental character
       set" above.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       ,,       \[Bq]   u201E     low double comma quote
       ,        \[bq]   u201A     low single comma quote
       "        \[lq]   u201C     left double quote
       "        \[rq]   u201D     right double quote
       `        \[oq]   u2018     single opening (left) quote
       '        \[cq]   u2019     single closing (right) quote
       '        \[aq]   u0027     apostrophe, neutral single quote
       "        "       u0022     neutral double quote
       "        \[dq]   u0022     neutral double quote
       <<       \[Fo]   u00AB     left double chevron
       >>       \[Fc]   u00BB     right double chevron
       <        \[fo]   u2039     left single chevron
       >        \[fc]   u203A     right single chevron

   Punctuation
       The Unicode name for U+00B7 is "middle dot", which is unfortunately
       confusable with the groff mnemonic for the visually similar but
       semantically distinct multiplication dot; see subsection "Mathematical
       symbols" below.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       !        \[r!]   u00A1     inverted exclamation mark
       ?        \[r?]   u00BF     inverted question mark
       .        \[pc]   u00B7     centered period
       --       \[em]   u2014     em-dash +
       -        \[en]   u2013     en-dash
       -        \[hy]   u2010     hyphen +

   Brackets
       On typesetting devices, the bracket extensions are font-invariant
       glyphs; that is, they are rendered the same way regardless of font
       (with a drawing escape sequence).  On terminals, they are not font-
       invariant; groff maps them rather arbitrarily to U+23AA ("curly bracket
       extension").  In AT&T troff, only one glyph was available to vertically
       extend brackets, braces, and parentheses: \(bv.

       Not all devices supply bracket pieces that can be piled up with \b due
       to the restrictions of the escape's piling algorithm.  A general
       solution to build brackets out of pieces is the following macro:
              .\" Make a pile centered vertically 0.5em above the baseline.
              .\" The first argument is placed at the top.
              .\" The pile is returned in string 'pile'.
              .eo
              .de pile-make
              .  nr pile-wd 0
              .  nr pile-ht 0
              .  ds pile-args
              .
              .  nr pile-# \n[.$]
              .  while \n[pile-#] \{\
              .    nr pile-wd (\n[pile-wd] >? \w'\$[\n[pile-#]]')
              .    nr pile-ht +(\n[rst] - \n[rsb])
              .    as pile-args \v'\n[rsb]u'\"
              .    as pile-args \Z'\$[\n[pile-#]]'\"
              .    as pile-args \v'-\n[rst]u'\"
              .    nr pile-# -1
              .  \}
              .
              .  ds pile \v'(-0.5m + (\n[pile-ht]u / 2u))'\"
              .  as pile \*[pile-args]\"
              .  as pile \v'((\n[pile-ht]u / 2u) + 0.5m)'\"
              .  as pile \h'\n[pile-wd]u'\"
              ..
              .ec

       Another complication is the fact that some glyphs which represent
       bracket pieces in AT&T troff can be used for other mathematical symbols
       as well, for example \(lf and \(rf, which provide the floor operator.
       Some output devices, such as dvi, don't unify such glyphs.  For this
       reason, the glyphs \[lf], \[rf], \[lc], and \[rc] are not unified with
       similar-looking bracket pieces.  In groff, only glyphs with long names
       are guaranteed to pile up correctly for all devices--provided those
       glyphs are available.

       Output   Input               Unicode   Notes
       ------------------------------------------------------------------------
       [        [                   u005B     left square bracket
       [        \[lB]               u005B     left square bracket
       ]        ]                   u005D     right square bracket
       ]        \[rB]               u005D     right square bracket
       {        {                   u007B     left brace
       {        \[lC]               u007B     left brace
       }        }                   u007D     right brace
       }        \[rC]               u007D     right brace
       <        \[la]               u27E8     left angle bracket
       >        \[ra]               u27E9     right angle bracket
       |        \[bv]               u23AA     brace vertical extension + ***
       |        \[braceex]          u23AA     brace vertical extension

       |        \[bracketlefttp]    u23A1     left square bracket top
       |        \[bracketleftex]    u23A2     left square bracket extension
       |        \[bracketleftbt]    u23A3     left square bracket bottom

       |        \[bracketrighttp]   u23A4     right square bracket top
       |        \[bracketrightex]   u23A5     right square bracket extension
       |        \[bracketrightbt]   u23A6     right square bracket bottom

       ,-       \[lt]               u23A7     left brace top +
       {        \[lk]               u23A8     left brace middle +
       `-       \[lb]               u23A9     left brace bottom +
       ,-       \[bracelefttp]      u23A7     left brace top
       {        \[braceleftmid]     u23A8     left brace middle
       `-       \[braceleftbt]      u23A9     left brace bottom
       |        \[braceleftex]      u23AA     left brace extension

       -.       \[rt]               u23AB     right brace top +
       }        \[rk]               u23AC     right brace middle +
       -'       \[rb]               u23AD     right brace bottom +
       -.       \[bracerighttp]     u23AB     right brace top
       }        \[bracerightmid]    u23AC     right brace middle
       -'       \[bracerightbt]     u23AD     right brace bottom
       |        \[bracerightex]     u23AA     right brace extension

       /        \[parenlefttp]      u239B     left parenthesis top
       |        \[parenleftex]      u239C     left parenthesis extension
       \        \[parenleftbt]      u239D     left parenthesis bottom
       \        \[parenrighttp]     u239E     right parenthesis top
       |        \[parenrightex]     u239F     right parenthesis extension
       /        \[parenrightbt]     u23A0     right parenthesis bottom

   Arrows

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       <-       \[<-]   u2190     horizontal arrow left +
       ->       \[->]   u2192     horizontal arrow right +
       <->      \[<>]   u2194     bidirectional horizontal arrow
       v        \[da]   u2193     vertical arrow down +
       ^        \[ua]   u2191     vertical arrow up +
       ^v       \[va]   u2195     bidirectional vertical arrow
       <=       \[lA]   u21D0     horizontal double arrow left
       =>       \[rA]   u21D2     horizontal double arrow right
       <=>      \[hA]   u21D4     bidirectional horizontal double arrow
       v        \[dA]   u21D3     vertical double arrow down
       ^        \[uA]   u21D1     vertical double arrow up
       ^=v      \[vA]   u21D5     bidirectional vertical double arrow
       -        \[an]   u23AF     horizontal arrow extension

   Rules and lines
       On typesetting devices, the font-invariant glyphs (see subsection
       "Brackets" above) \[br], \[ul], and \[rn] form corners when adjacent;
       they can be used to build boxes.  On terminal devices, they are mapped
       as shown in the table.  The Unicode-derived names of these three glyphs
       are approximations.

       The input character _ always accesses the underscore glyph in a font;
       \[ul], by contrast, may be font-invariant on typesetting devices.

       The baseline rule \[ru] is a font-invariant glyph, namely a rule of
       one-half em.

       In AT&T troff, \[rn] also served as a one en extension of the square
       root symbol.  groff favors \[radicalex] for this purpose; see
       subsection "Mathematical symbols" below.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       |        |       u007C     bar
       |        \[ba]   u007C     bar
       |        \[br]   u2502     box rule +
       _        _       u005F     underscore, low line +
       _        \[ul]   ---       underrule +
       -        \[rn]   u203E     overline +
       _        \[ru]   ---       baseline rule +
       |        \[bb]   u00A6     broken bar
       /        /       u002F     slash, solidus +
       /        \[sl]   u002F     slash, solidus +
       \        \[rs]   u005C     reverse solidus

   Text markers

       Output        Input   Unicode   Notes
       ------------------------------------------------------------------------
       O             \[ci]   u25CB     circle +
       o             \[bu]   u2022     bullet +
       <*>           \[dg]   u2020     dagger +
       <**>          \[dd]   u2021     double dagger +
       <>            \[lz]   u25CA     lozenge, diamond
       []            \[sq]   u25A1     square +
       <paragraph>   \[ps]   u00B6     pilcrow sign
       <section>     \[sc]   u00A7     section sign +
       <=            \[lh]   u261C     hand pointing left +
       =>            \[rh]   u261E     hand pointing right +
       @             @       u0040     at sign
       @             \[at]   u0040     at sign
       #             #       u0023     number sign
       #             \[sh]   u0023     number sign
       <cr>          \[CR]   u21B5     carriage return
       \/            \[OK]   u2713     check mark

   Legal symbols
       The Bell System logo is not supported in groff.

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       (C)      \[co]   u00A9     copyright sign +
       (R)      \[rg]   u00AE     registered sign +
       tm       \[tm]   u2122     trade mark sign
                \[bs]   ---       Bell System logo +

   Currency symbols

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       $        $       u0024     dollar sign
       $        \[Do]   u0024     dollar sign
       c        \[ct]   u00A2     cent sign +
       EUR      \[eu]   u20AC     Euro sign
       EUR      \[Eu]   u20AC     variant Euro sign
       Y        \[Ye]   u00A5     yen sign
       L        \[Po]   u00A3     pound sign
       x        \[Cs]   u00A4     currency sign

   Units

       Output       Input   Unicode   Notes
       ------------------------------------------------------------------------
       <degree>     \[de]   u00B0     degree sign +
       <permille>   \[%0]   u2030     per thousand, per mille sign
       '            \[fm]   u2032     arc minute sign, foot mark +
       ''           \[sd]   u2033     arc second sign
       <micro>      \[mc]   u00B5     micro sign
       a            \[Of]   u00AA     feminine ordinal indicator
       o            \[Om]   u00BA     masculine ordinal indicator

   Logical symbols
       The variants of the not sign may differ in appearance or spacing
       depending on the device and font selected.  Unicode does not encode a
       discrete "bitwise or" sign: on typesetting devices, it is drawn shorter
       than the bar, about the same height as a capital letter.  Terminal
       devices unify \[ba] and \[or].

       Output           Input    Unicode   Notes
       ------------------------------------------------------------------------
       ^                \[AN]    u2227     logical and
       v                \[OR]    u2228     logical or
       ~                \[no]    u00AC     logical not + ***
       ~                \[tno]   u00AC     text variant of \[no]
       <there exists>   \[te]    u2203     there exists
       <for all>        \[fa]    u2200     for all
       <such that>      \[st]    u220B     such that
       <therefore>      \[3d]    u2234     therefore
       <therefore>      \[tf]    u2234     therefore
       |                |        u007C     bar
       |                \[or]    u007C     bitwise or +

   Mathematical symbols
       \[Fn] also appears in subsection "Supplementary Latin letters" above.
       Observe the two varieties of the plus-minus, multiplication, and
       division signs; \[+-], \[mu], and \[di] are normally drawn from the
       special font, but have text font variants.  Also be aware of three
       glyphs available in special font variants that are normally drawn from
       text fonts: the plus, minus, and equals signs.  These variants may
       differ in appearance or spacing depending on the device and font
       selected.

       In AT&T troff, \(rn ("root en extender") served as the horizontal
       extension of the radical (square root) sign, \(sr, and was drawn at the
       maximum height of the typeface's bounding box; this enabled the special
       character to double as an overline (see subsection "Rules and lines"
       above).  A contemporary font's radical sign might not ascend to such an
       extreme.  In groff, you can instead use \[radicalex] to continue the
       radical sign \[sr]; these special characters are intended for use with
       text fonts.  \[sqrt] and \[sqrtex] are their counterparts with
       mathematical spacing.

       Output                Input          Unicode      Notes
       ------------------------------------------------------------------------
       1/2                   \[12]          u00BD        one half symbol +
       1/4                   \[14]          u00BC        one quarter symbol +
       3/4                   \[34]          u00BE        three quarters symbol
                                                         +
       1/8                   \[18]          u215B        one eighth symbol
       3/8                   \[38]          u215C        three eighths symbol
       5/8                   \[58]          u215D        five eighths symbol
       7/8                   \[78]          u215E        seven eighths symbol
       ^1                    \[S1]          u00B9        superscript one
       ^2                    \[S2]          u00B2        superscript two
       ^3                    \[S3]          u00B3        superscript three

       +                     +              u002B        plus
       +                     \[pl]          u002B        special variant of
                                                         plus + ***
       -                     \[-]           u002D        minus
       -                     \[mi]          u2212        special variant of
                                                         minus + ***
       -+                    \[-+]          u2213        minus-plus
       +-                    \[+-]          u00B1        plus-minus + ***
       +-                    \[t+-]         u00B1        text variant of \[+-]
       .                     \[md]          u22C5        multiplication dot
       x                     \[mu]          u00D7        multiplication sign +
                                                         ***
       x                     \[tmu]         u00D7        text variant of \[mu]
       x                     \[c*]          u2297        circled times
       +                     \[c+]          u2295        circled plus
       /                     \[di]          u00F7        division sign + ***
       /                     \[tdi]         u00F7        text variant of \[di]
       /                     \[f/]          u2044        fraction slash
       *                     *              u002A        asterisk
       *                     \[**]          u2217        mathematical asterisk
                                                         +

       <=                    \[<=]          u2264        less than or equal to
                                                         +
       >=                    \[>=]          u2265        greater than or equal
                                                         to +
       <<                    \[<<]          u226A        much less than
       >>                    \[>>]          u226B        much greater than
       =                     =              u003D        equals
       =                     \[eq]          u003D        special variant of
                                                         equals + ***
       !=                    \[!=]          u003D_0338   not equals +
       ==                    \[==]          u2261        equivalent +
       !==                   \[ne]          u2261_0338   not equivalent
       =~                    \[=~]          u2245        approximately equal
                                                         to
       -~                    \[|=]          u2243        asymptotically equal
                                                         to +
       ~                     \[ti]          u007E        tilde +
       ~                     \[ap]          u223C        similar to, tilde
                                                         operator +
       ~~                    \[~~]          u2248        almost equal to
       ~=                    \[~=]          u2248        almost equal to
       <proportional to>     \[pt]          u221D        proportional to +

       {}                    \[es]          u2205        empty set +
       <element of>          \[mo]          u2208        element of a set +
       <not element of>      \[nm]          u2208_0338   not element of set
       <proper subset>       \[sb]          u2282        proper subset +
       <not subset>          \[nb]          u2282_0338   not subset
       <proper superset>     \[sp]          u2283        proper superset +
       <not superset>        \[nc]          u2283_0338   not superset
       <subset or equal>     \[ib]          u2286        subset or equal +
       <superset or equal>   \[ip]          u2287        superset or equal +
       <intersection>        \[ca]          u2229        intersection, cap +
       <union>               \[cu]          u222A        union, cup +

       <angle>               \[/_]          u2220        angle
       <perpendicular>       \[pp]          u22A5        perpendicular
       <integral>            \[is]          u222B        integral +
       <integral>            \[integral]    u222B        integral ***
       <sum>                 \[sum]         u2211        summation ***
       <product>             \[product]     u220F        product ***
       <coproduct>           \[coproduct]   u2210        coproduct ***
       <nabla>               \[gr]          u2207        gradient +
       <sqrt>                \[sr]          u221A        radical sign, square
                                                         root +
       -                     \[rn]          u203E        overline +
                             \[radicalex]   ---          radical extension
       <sqrt>                \[sqrt]        u221A        radical sign, square
                                                         root ***
                             \[sqrtex]      ---          radical extension ***

       |~                    \[lc]          u2308        left ceiling +
       ~|                    \[rc]          u2309        right ceiling +
       |_                    \[lf]          u230A        left floor +
       _|                    \[rf]          u230B        right floor +

       <infinity>            \[if]          u221E        infinity +
       <Aleph>               \[Ah]          u2135        aleph symbol
       f                     \[Fn]          u0192        lowercase f with
                                                         hook, function
       <Im>                  \[Im]          u2111        blackletter I,
                                                         imaginary part
       <Re>                  \[Re]          u211C        blackletter R, real
                                                         part
       p                     \[wp]          u2118        Weierstrass p
       <del>                 \[pd]          u2202        partial differential
       /h                    \[-h]          u210F        h bar
       /h                    \[hbar]        u210F        h bar

   Greek glyphs
       These glyphs are intended for technical use, not for typesetting Greek
       language text; normally, the uppercase letters have upright shape, and
       the lowercase ones are slanted.

       Output      Input   Unicode   Notes
       ------------------------------------------------------------------------
       A           \[*A]   u0391     uppercase alpha +
       B           \[*B]   u0392     uppercase beta +
       <Gamma>     \[*G]   u0393     uppercase gamma +
       <Delta>     \[*D]   u0394     uppercase delta +
       E           \[*E]   u0395     uppercase epsilon +
       Z           \[*Z]   u0396     uppercase zeta +
       H           \[*Y]   u0397     uppercase eta +
       <Theta>     \[*H]   u0398     uppercase theta +
       I           \[*I]   u0399     uppercase iota +
       K           \[*K]   u039A     uppercase kappa +
       <Lambda>    \[*L]   u039B     uppercase lambda +
       M           \[*M]   u039C     uppercase mu +
       N           \[*N]   u039D     uppercase nu +
       <Xi>        \[*C]   u039E     uppercase xi +
       O           \[*O]   u039F     uppercase omicron +
       <Pi>        \[*P]   u03A0     uppercase pi +
       P           \[*R]   u03A1     uppercase rho +
       <Sigma>     \[*S]   u03A3     uppercase sigma +
       T           \[*T]   u03A4     uppercase tau +
       Y           \[*U]   u03A5     uppercase upsilon +
       <Phi>       \[*F]   u03A6     uppercase phi +
       X           \[*X]   u03A7     uppercase chi +
       <Psi>       \[*Q]   u03A8     uppercase psi +
       <Omega>     \[*W]   u03A9     uppercase omega +

       <alpha>     \[*a]   u03B1     lowercase alpha +
       <beta>      \[*b]   u03B2     lowercase beta +
       <gamma>     \[*g]   u03B3     lowercase gamma +
       <delta>     \[*d]   u03B4     lowercase delta +
       <epsilon>   \[*e]   u03B5     lowercase epsilon +
       <zeta>      \[*z]   u03B6     lowercase zeta +
       <eta>       \[*y]   u03B7     lowercase eta +
       <theta>     \[*h]   u03B8     lowercase theta +
       <iota>      \[*i]   u03B9     lowercase iota +
       <kappa>     \[*k]   u03BA     lowercase kappa +
       <lambda>    \[*l]   u03BB     lowercase lambda +
       <mu>        \[*m]   u03BC     lowercase mu +
       <nu>        \[*n]   u03BD     lowercase nu +
       <xi>        \[*c]   u03BE     lowercase xi +
       o           \[*o]   u03BF     lowercase omicron +
       <pi>        \[*p]   u03C0     lowercase pi +
       <rho>       \[*r]   u03C1     lowercase rho +
       <sigma>     \[*s]   u03C3     lowercase sigma +
       <tau>       \[*t]   u03C4     lowercase tau +
       <upsilon>   \[*u]   u03C5     lowercase upsilon +
       <phi>       \[*f]   u03D5     lowercase phi +
       <chi>       \[*x]   u03C7     lowercase chi +
       <psi>       \[*q]   u03C8     lowercase psi +
       <omega>     \[*w]   u03C9     lowercase omega +

       <epsilon>   \[+e]   u03F5     variant epsilon (lunate)
       <theta>     \[+h]   u03D1     variant theta (cursive form)
       <pi>        \[+p]   u03D6     variant pi (similar to omega)
       <phi>       \[+f]   u03C6     variant phi (curly shape)
       <sigma>     \[ts]   u03C2     terminal lowercase sigma +

   Playing card symbols

       Output   Input   Unicode   Notes
       ------------------------------------------------------------------------
       C        \[CL]   u2663     solid club suit
       S        \[SP]   u2660     solid spade suit
       H        \[HE]   u2665     solid heart suit
       D        \[DI]   u2666     solid diamond suit


History

       A consideration of the typefaces originally available to AT&T nroff and
       troff illuminates many conventions that one might regard as
       idiosyncratic fifty years afterward.  (See section "History" of roff(7)
       for more context.)  The face used by the Teletype Model 37 terminals of
       the Murray Hill Unix Room was based on ASCII, but assigned multiple
       meanings to several code points, as suggested by that standard.
       Decimal 34 (") served as a dieresis accent and neutral double quotation
       mark; decimal 39 (') as an acute accent, apostrophe, and closing
       (right) single quotation mark; decimal 45 (-) as a hyphen and a minus
       sign; decimal 94 (^) as a circumflex accent and caret; decimal 96 (`)
       as a grave accent and opening (left) single quotation mark; and decimal
       126 (~) as a tilde accent and (with a half-line motion) swung dash.
       The Model 37 bore an optional extended character set offering upright
       Greek letters and several mathematical symbols; these were documented
       as early as the kbd(VII) man page of the (First Edition) Unix
       Programmer's Manual.

       At the time Graphic Systems delivered the C/A/T phototypesetter to
       AT&T, the ASCII character set was not considered a standard basis for a
       glyph repertoire by traditional typographers.  In the stock Times
       roman, italic, and bold styles available, several ASCII characters were
       not present at all, nor was most of the Teletype's extended character
       set.  AT&T commissioned a "special" font to ensure no loss of
       repertoire.

       A representation of the coverage of the C/A/T's text fonts follows.
       The glyph resembling an underscore is a baseline rule, and that
       resembling a vertical line is a box rule.  In italics, the box rule was
       not slanted.  We also observe that the hyphen and minus sign were
       already "de-unified" by the fonts provided; a decision whither to map
       an input "-" therefore had to be taken.

               +-----------------------------------------------------+
               |A B C D E F G H I J K L M N O P Q R S T U V W X Y Z  |
               |a b c d e f g h i j k l m n o p q r s t u v w x y z  |
               |0 1 2 3 4 5 6 7 8 9 fi fl ffi ffl                    |
               |! $ % & ( ) ` ' * + - . , / : ; = ? [ ] |            |
               |o [] -- - _ 1/4 1/2 3/4 <degree> <*> ' c (R) (C)     |
               +-----------------------------------------------------+
       The special font supplied the missing ASCII and Teletype extended
       glyphs, among several others.  The plus, minus, and equals signs
       appeared in the special font despite availability in text fonts "to
       insulate the appearance of equations from the choice of standard [read:
       text] fonts"--a priority since troff was turned to the task of
       mathematical typesetting as soon as it was developed.

       We note that AT&T took the opportunity to de-unify the apostrophe/right
       single quotation mark from the acute accent (a choice ISO later
       duplicated in its 8859 series of standards).  A slash intended to be
       mirror-symmetric with the backslash was also included, as was the Bell
       System logo; we do not attempt to depict the latter.

+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|<alpha> <beta> <gamma> <delta> <epsilon> <zeta> <eta> <theta> <iota> <kappa> <lambda> <mu> <nu> <xi> o <pi> <rho> <sigma> <sigma> <tau> <upsilon> <phi> <chi> <psi> <omega>                                          |
|<Gamma> <Delta> <Theta> <Lambda> <Xi> <Pi> <Sigma> Y <Phi> <Psi> <Omega>                                                                                                                                             |
|" ' \ ^ _ ` ~ / < > { } # @ + - = *                                                                                                                                                                                  |

|>= <= == ~= ~ != ^ v <- -> x / +- ~ {} |

|<section> <**> <= => | O ,- `- -. -' { } | |_ _| |~ ~|                                                                                                                                                               |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
       One ASCII character as rendered by the Model 37 was apparently
       abandoned.  That device printed decimal 124 (|) as a broken vertical
       line, like Unicode U+00A6 (|).  No equivalent was available on the
       C/A/T; the box rule \[br], brace vertical extension \[bv], and "or"
       operator \[or] were used as contextually appropriate.

       Devices supported by AT&T device-independent troff exhibited some
       differences in glyph detail.  For example, on the Autologic APS-5
       phototypesetter, the square \(sq became filled in the Times bold face.


Files

       The files below are loaded automatically by the default troffrc.

       /opt/local/share/groff/1.23.0/tmac/composite.tmac
              assigns alternate mappings for identifiers after the first in a
              composite special character escape sequence.  See subsection
              "Accents" above.

       /opt/local/share/groff/1.23.0/tmac/fallbacks.tmac
              defines fallback mappings for Unicode code points such as the
              increment sign (U+2206) and upper- and lowercase Roman numerals.


Authors

       This document was written by James Clark <jjc@jclark.com>, with
       additions by Werner Lemberg <wl@gnu.org> and Bernd Warken <groff-bernd
       .warken-72@web.de>, revised to use tbl(1) by Eric S. Raymond <esr@
       thyrsus.com>, and largely rewritten by G. Branden Robinson <g.branden
       .robinson@gmail.com>.


See also

       Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner
       Lemberg, is the primary groff manual.  Section "Using Symbols" may be
       of particular note.  You can browse it interactively with "info
       '(groff) Using Symbols'".

       "An extension to the troff character set for Europe", E.G. Keizer, K.J.
       Simonsen, J. Akkerhuis; EUUG Newsletter, Volume 9, No. 2, Summer 1989

       The Unicode Standard <http://www.unicode.org>

       "7-bit Character Sets" <https://www.aivosto.com/articles/charsets-7bit
       .html> by Tuomas Salste documents the inherent ambiguity and
       configurable code points of the ASCII encoding standard.

       "Nroff/Troff User's Manual" by Joseph F. Ossanna, 1976, AT&T Bell
       Laboratories Computing Science Technical Report No. 54, features two
       tables that throw light on the glyph repertoire available to
       "typesetter roff" when it was first written.  Be careful of re-typeset
       versions of this document that can be found on the Internet.  Some do
       not accurately represent the original document: several glyphs are
       obviously missing.  More subtly, lowercase Greek letters are rendered
       upright, not slanted as they appeared in the C/A/T's special font and
       as expected by troff users.

       groff_rfc1345(7) describes an alternative set of special character
       glyph names, which extends and in some cases overrides the definitions
       listed above.

       groff(1), troff(1), groff(7)

groff 1.23.0                      2 July 2023                    groff_char(7)

groff 1.23.0 - Generated Fri Dec 22 13:27:49 CST 2023
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