# groff_char

## 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 ISO Latin‐1
           (ISO 8859‐1) standard.  For ease of document maintenance in UTF‐8
           environments, it is advisable to use only the Unicode basic Latin
           code points; these correspond to ISO 646:1991 IRV (US‐ASCII), a
           subset of all of the foregoing 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 **utf8** primarily using font **R**.
    
           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_ , test 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.
    
           While _groff_ accepts eight‐bit encoded input, not all such code
           points are valid as input.  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].)
           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.  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.
    
           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 to prepare
           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 at the beginning of
           an argument.)  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 _troff_ s.  **\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     │
         │ ^        ˆ 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 file name or
           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 expressions, 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 and
           its kerning configuration).
          ┌─────────────────────────────────────────────────────────────────┐
          │ 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 dedicated features for drawing
           horizontal and vertical lines, the **\l** , **\L** , and **\D** escape
           sequences.  Also 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 Latin‐1 (8859‐1) 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 GNU _troff_ input.
    
           GNU _troff_ handles two Latin‐1 supplement characters specially, and
           never produces them as output.
    
           NBSP   encodes a no‐break space; it maps to **\~** , the adjustable
                  non‐breaking space escape sequence.
    
           SHY    encodes a soft hyphen; it maps 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     Ñ  \[~N] N tilde
           ¢  \[ct] cent sign                     Ò  \[`O] O grave
           £  \[Po] pound sign                    Ó  \['O] O acute
           ¤  \[Cs] currency sign                 Ô  \[^O] O circumflex
           ¥  \[Ye] yen sign                      Õ  \[~O] O tilde
           ¦  \[bb] broken bar                    Ö  \[:O] O dieresis
           §  \[sc] section sign                  ×  \[mu] multiplication sign
           ¨  \[ad] dieresis accent               Ø  \[/O] O slash
           ©  \[co] copyright sign                Ù  \[`U] U grave
           ª  \[Of] feminine ordinal indicator    Ú  \['U] U acute
           «  \[Fo] left double chevron           Û  \[^U] U circumflex
           ¬  \[no] logical not                   Ü  \[:U] U dieresis
           ®  \[rg] registered sign               Ý  \['Y] Y acute
           ¯  \[a-] macron accent                 Þ  \[TP] uppercase thorn
           °  \[de] degree sign                   ß  \[ss] lowercase sharp s
           ±  \[+-] plus‐minus                    à  \[`a] a grave
           ²  \[S2] superscript two               á  \['a] a acute
           ³  \[S3] superscript three             â  \[^a] a circumflex
           ´  \[aa] acute accent                  ã  \[~a] a tilde
           µ  \[mc] micro sign                    ä  \[:a] a dieresis
           ¶  \[ps] pilcrow sign                  å  \[oa] a ring
           ·  \[pc] centered period               æ  \[ae] ae ligature
           ¸  \[ac] cedilla accent                ç  \[,c] c cedilla
           ¹  \[S1] superscript one               è  \[`e] e grave
           º  \[Om] masculine ordinal indicator   é  \['e] e acute
           »  \[Fc] right double chevron          ê  \[^e] e circumflex
           ¼  \[14] one quarter symbol            ë  \[:e] e dieresis
           ½  \[12] one half symbol               ì  \[`i] i grave
           ¾  \[34] three quarters symbol         í  \['i] e acute
           ¿  \[r?] inverted question mark        î  \[^i] i circumflex
           À  \[`A] A grave                       ï  \[:i] i dieresis
           Á  \['A] A acute                       ð  \[Sd] lowercase eth
           Â  \[^A] A circumflex                  ñ  \[~n] n tilde
           Ã  \[~A] A tilde                       ò  \[`o] o grave
           Ä  \[:A] A dieresis                    ó  \['o] o acute
           Å  \[oA] A ring                        ô  \[^o] o circumflex
           Æ  \[AE] AE ligature                   õ  \[~o] o tilde
           Ç  \[,C] C cedilla                     ö  \[:o] o dieresis
           È  \[`E] E grave                       ÷  \[di] division sign
           É  \['E] E acute                       ø  \[/o] o slash
           Ê  \[^E] E circumflex                  ù  \[`u] u grave
           Ë  \[:E] E dieresis                    ú  \['u] u acute
           Ì  \[`I] I grave                       û  \[^u] u circumflex
           Í  \['I] I acute                       ü  \[:u] u dieresis
           Î  \[^I] I circumflex                  ý  \['y] y acute
           Ï  \[:I] I dieresis                    þ  \[Tp] lowercase thorn
           Ð  \[-D] uppercase eth                 ÿ  \[: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 in GNU _troff_ 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 “café”, can be expressed as
                  **\[e aa]**.
    
           Normally, the formatter advances the drawing position after
           setting a special character, as it does for ordinary ones.
           _groff_ ’s **composite** request designates a special character as
           combining, suppressing advancement.
    
           You can obtain a report of mappings defined by the **composite**
           request on the standard error stream with the **pcomposite** request.
           The _composite.tmac_ macro file, loaded automatically by the default
           _troffrc_ , maps certain special characters to combining characters
           as shown in subsection “Accents” below.
    
           Unicode encodes far more characters than _groff_ has 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).
    
           **\[u** _nnnn_[_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 “˚”.
    
           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 “café”.  (Due to its legacy 8‐bit encoding compatibility,
           at present it also accepts “caf**\[u00E9]** ” on ISO Latin‐1 systems.)
    
           **\[u** _base‐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 “ñ”.
    
           **\[char** _nnn_**]**
                  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
                  **u** _nnnn_ 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 that 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
                  expressions.  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 unstyled 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]** developed from 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
           ───────────────────────────────────────────────────────────────────
           Ð        \[-D]   u00D0     uppercase eth
           ð        \[Sd]   u00F0     lowercase eth
           Þ        \[TP]   u00DE     uppercase thorn
           þ        \[Tp]   u00FE     lowercase thorn
           ß        \[ss]   u00DF     lowercase sharp s
           ı        \[.i]   u0131     i without tittle
           ȷ        \[.j]   u0237     j without tittle
           ƒ        \[Fn]   u0192     lowercase f with hook, function
           Ł        \[/L]   u0141     L with stroke
           ł        \[/l]   u0142     l with stroke
           Ø        \[/O]   u00D8     O with stroke
           ø        \[/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 +
           Æ        \[AE]   u00C6             AE ligature
           æ        \[ae]   u00E6             ae ligature
           Œ        \[OE]   u0152             OE ligature
           œ        \[oe]   u0153             oe ligature
           Ĳ        \[IJ]   u0132             IJ digraph
           ĳ        \[ij]   u0133             ij digraph
    
       **Accents**
           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
           ˇ        \[ah]   u030C (u02C7)   caron accent
           ˚        \[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
           ───────────────────────────────────────────────────────────────────
           Á        \['A]   u0041_0301   A acute
           Ć        \['C]   u0043_0301   C acute
           É        \['E]   u0045_0301   E acute
           Í        \['I]   u0049_0301   I acute
           Ó        \['O]   u004F_0301   O acute
           Ú        \['U]   u0055_0301   U acute
           Ý        \['Y]   u0059_0301   Y acute
           á        \['a]   u0061_0301   a acute
           ć        \['c]   u0063_0301   c acute
           é        \['e]   u0065_0301   e acute
           í        \['i]   u0069_0301   i acute
           ó        \['o]   u006F_0301   o acute
           ú        \['u]   u0075_0301   u acute
           ý        \['y]   u0079_0301   y acute
    
           Ä        \[:A]   u0041_0308   A dieresis
           Ë        \[:E]   u0045_0308   E dieresis
           Ï        \[:I]   u0049_0308   I dieresis
           Ö        \[:O]   u004F_0308   O dieresis
           Ü        \[:U]   u0055_0308   U dieresis
           Ÿ        \[:Y]   u0059_0308   Y dieresis
           ä        \[:a]   u0061_0308   a dieresis
           ë        \[:e]   u0065_0308   e dieresis
           ï        \[:i]   u0069_0308   i dieresis
           ö        \[:o]   u006F_0308   o dieresis
           ü        \[:u]   u0075_0308   u dieresis
           ÿ        \[:y]   u0079_0308   y dieresis
    
           Â        \[^A]   u0041_0302   A circumflex
           Ê        \[^E]   u0045_0302   E circumflex
           Î        \[^I]   u0049_0302   I circumflex
           Ô        \[^O]   u004F_0302   O circumflex
           Û        \[^U]   u0055_0302   U circumflex
           â        \[^a]   u0061_0302   a circumflex
           ê        \[^e]   u0065_0302   e circumflex
           î        \[^i]   u0069_0302   i circumflex
           ô        \[^o]   u006F_0302   o circumflex
           û        \[^u]   u0075_0302   u circumflex
    
           À        \[`A]   u0041_0300   A grave
           È        \[`E]   u0045_0300   E grave
           Ì        \[`I]   u0049_0300   I grave
           Ò        \[`O]   u004F_0300   O grave
           Ù        \[`U]   u0055_0300   U grave
           à        \[`a]   u0061_0300   a grave
           è        \[`e]   u0065_0300   e grave
           ì        \[`i]   u0069_0300   i grave
           ò        \[`o]   u006F_0300   o grave
           ù        \[`u]   u0075_0300   u grave
    
           Ã        \[~A]   u0041_0303   A tilde
           Ñ        \[~N]   u004E_0303   N tilde
           Õ        \[~O]   u004F_0303   O tilde
           ã        \[~a]   u0061_0303   a tilde
           ñ        \[~n]   u006E_0303   n tilde
           õ        \[~o]   u006F_0303   o tilde
    
           Š        \[vS]   u0053_030C   S caron
           š        \[vs]   u0073_030C   s caron
           Ž        \[vZ]   u005A_030C   Z caron
           ž        \[vz]   u007A_030C   z caron
    
           Ç        \[,C]   u0043_0327   C cedilla
           ç        \[,c]   u0063_0327   c cedilla
    
           Å        \[oA]   u0041_030A   A ring
           å        \[oa]   u0061_030A   a ring
    
       **Quotation marks**
           The neutral double quote, useful in 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
           ‐        -       u2010     hyphen +
           ‐        \[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 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 formatter’s piling algorithm.  The
           following macro offers a more general bracket‐building solution.
                  .\" 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
    
           Further complicating matters is that some glyphs representing
           bracket pieces in AT&T _troff_ can be used for other mathematical
           symbols as well; for example, **\(lf** and **\(rf** 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
           ↓        \[da]   u2193     vertical arrow down +
           ↑        \[ua]   u2191     vertical arrow up +
           ↕        \[va]   u2195     bidirectional vertical arrow
           ⇐        \[lA]   u21D0     horizontal double arrow left
           ⇒        \[rA]   u21D2     horizontal double arrow right
           ⇔        \[hA]   u21D4     bidirectional horizontal double arrow
           ⇓        \[dA]   u21D3     vertical double arrow down
           ⇑        \[uA]   u21D1     vertical double arrow up
           ⇕        \[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 ordinary character **_** 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
           ───────────────────────────────────────────────────────────────────
           ○        \[ci]   u25CB     circle +
           •        \[bu]   u2022     bullet +
           †        \[dg]   u2020     dagger +
           ‡        \[dd]   u2021     double dagger +
           ◊        \[lz]   u25CA     lozenge, diamond
           □        \[sq]   u25A1     square +
           ¶        \[ps]   u00B6     pilcrow sign
           §        \[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]   u21B5     carriage return
           ✓        \[OK]   u2713     check mark
    
       **Legal symbols**
           The Bell System logo is not supported in _groff_.
    
           Output   Input   Unicode   Notes
           ───────────────────────────────────────────────────────────────────
           ©        \[co]   u00A9     copyright sign +
           ®        \[rg]   u00AE     registered sign +
           ™        \[tm]   u2122     trade mark sign
                    \[bs]   ‐‐‐       Bell System logo +
    
       **Currency symbols**
           Output   Input   Unicode   Notes
           ───────────────────────────────────────────────────────────────────
           $        $       u0024     dollar sign
           $        \[Do]   u0024     dollar sign
           ¢        \[ct]   u00A2     cent sign +
           €        \[eu]   u20AC     Euro sign
           €        \[Eu]   u20AC     variant Euro sign
           ¥        \[Ye]   u00A5     yen sign
           £        \[Po]   u00A3     pound sign
           ¤        \[Cs]   u00A4     currency sign
    
       **Units**
           Output   Input   Unicode   Notes
           ───────────────────────────────────────────────────────────────────
           °        \[de]   u00B0     degree sign +
           ‰        \[%0]   u2030     per thousand, per mille sign
           ′        \[fm]   u2032     arc minute sign, foot mark +
           ″        \[sd]   u2033     arc second sign
           µ        \[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
           ∨        \[OR]    u2228     logical or
           ¬        \[no]    u00AC     logical not + ***
           ¬        \[tno]   u00AC     text variant of **\[no]**
           ∃        \[te]    u2203     there exists
           ∀        \[fa]    u2200     for all
           ∋        \[st]    u220B     such that
           ∴        \[3d]    u2234     therefore
           ∴        \[tf]    u2234     therefore
           |        |        u007C     bar +
           |        \[or]    u007C     bitwise or +
    
       **Mathematical symbols**
           **\[Fn]** also appears in subsection “Supplementary Latin letters”
           above.  The plus‐minus, multiplication, and division signs, **\[+-]** ,
           **\[mu]** , and **\[di]** , are normally drawn from the special font, but
           have text font variants.  The plus, minus, and equals signs are
           normally drawn from text fonts, but have special font variants.
           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, enabling it
           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 unstyled
           counterparts.
    
           Output   Input          Unicode      Notes
           ─────────────────────────────────────────────────────────────────────
           ½        \[12]          u00BD        one half symbol +
           ¼        \[14]          u00BC        one quarter symbol +
           ¾        \[34]          u00BE        three quarters symbol +
           ⅛        \[18]          u215B        one eighth symbol
           ⅜        \[38]          u215C        three eighths symbol
           ⅝        \[58]          u215D        five eighths symbol
           ⅞        \[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
           ×        \[mu]          u00D7        multiplication sign + ***
           ×        \[tmu]         u00D7        text variant of **\[mu]**
           ⊗        \[c*]          u2297        circled times
           ⊕        \[c+]          u2295        circled plus
           ÷        \[di]          u00F7        division sign, obelus + ***
           ÷        \[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
           ∝        \[pt]          u221D        proportional to +
    
           ∅        \[es]          u2205        empty set +
           ∈        \[mo]          u2208        element of a set +
           ∉        \[nm]          u2208_0338   not element of set
           ⊂        \[sb]          u2282        proper subset +
           ⊄        \[nb]          u2282_0338   not subset
           ⊃        \[sp]          u2283        proper superset +
           ⊅        \[nc]          u2283_0338   not superset
           ⊆        \[ib]          u2286        subset or equal +
           ⊇        \[ip]          u2287        superset or equal +
           ∩        \[ca]          u2229        intersection, cap +
           ∪        \[cu]          u222A        union, cup +
    
           ∠        \[/_]          u2220        angle
           ⊥        \[pp]          u22A5        perpendicular
           ∫        \[is]          u222B        integral +
           ∫        \[integral]    u222B        integral ***
           ∑        \[sum]         u2211        summation ***
           ∏        \[product]     u220F        product ***
           ∐        \[coproduct]   u2210        coproduct ***
           ∇        \[gr]          u2207        gradient +
           √        \[sr]          u221A        radical sign, square root +
           ‾        \[rn]          u203E        overline +
           ‾        \[radicalex]   ‐‐‐          radical extension
           √        \[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 +
    
           ∞        \[if]          u221E        infinity +
           ℵ        \[Ah]          u2135        aleph symbol
           ƒ        \[Fn]          u0192        lowercase f with hook, function
           ℑ        \[Im]          u2111        blackletter I, imaginary part
           ℜ        \[Re]          u211C        blackletter R, real part
           ℘        \[wp]          u2118        Weierstrass p
           ∂        \[pd]          u2202        partial differential
           ℏ        \[-h]          u210F        h bar
           ℏ        \[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.  For the latter, we
           include in parentheses under “Unicode” more appropriate code
           points from the Mathematical Alphanumeric Symbols block of the
           Supplementary Multilingual Plane.
    
           Output   Input   Unicode          Notes
           ───────────────────────────────────────────────────────────────────
           Α        \[*A]   u0391            uppercase alpha +
           Β        \[*B]   u0392            uppercase beta +
           Γ        \[*G]   u0393            uppercase gamma +
           Δ        \[*D]   u0394            uppercase delta +
           Ε        \[*E]   u0395            uppercase epsilon +
           Ζ        \[*Z]   u0396            uppercase zeta +
           Η        \[*Y]   u0397            uppercase eta +
           Θ        \[*H]   u0398            uppercase theta +
           Ι        \[*I]   u0399            uppercase iota +
           Κ        \[*K]   u039A            uppercase kappa +
           Λ        \[*L]   u039B            uppercase lambda +
           Μ        \[*M]   u039C            uppercase mu +
           Ν        \[*N]   u039D            uppercase nu +
           Ξ        \[*C]   u039E            uppercase xi +
           Ο        \[*O]   u039F            uppercase omicron +
           Π        \[*P]   u03A0            uppercase pi +
           Ρ        \[*R]   u03A1            uppercase rho +
           Σ        \[*S]   u03A3            uppercase sigma +
           Τ        \[*T]   u03A4            uppercase tau +
           Υ        \[*U]   u03A5            uppercase upsilon +
           Φ        \[*F]   u03A6            uppercase phi +
           Χ        \[*X]   u03A7            uppercase chi +
           Ψ        \[*Q]   u03A8            uppercase psi +
           Ω        \[*W]   u03A9            uppercase omega +
    
           α        \[*a]   u03B1 (u1D6FC)   lowercase alpha +
           β        \[*b]   u03B2 (u1D6FD)   lowercase beta +
           γ        \[*g]   u03B3 (u1D6FE)   lowercase gamma +
           δ        \[*d]   u03B4 (u1D6FF)   lowercase delta +
           ε        \[*e]   u03B5 (u1D700)   lowercase epsilon +
           ζ        \[*z]   u03B6 (u1D701)   lowercase zeta +
           η        \[*y]   u03B7 (u1D702)   lowercase eta +
           θ        \[*h]   u03B8 (u1D703)   lowercase theta +
           ι        \[*i]   u03B9 (u1D704)   lowercase iota +
           κ        \[*k]   u03BA (u1D705)   lowercase kappa +
           λ        \[*l]   u03BB (u1D706)   lowercase lambda +
           μ        \[*m]   u03BC (u1D707)   lowercase mu +
           ν        \[*n]   u03BD (u1D708)   lowercase nu +
           ξ        \[*c]   u03BE (u1D709)   lowercase xi +
           ο        \[*o]   u03BF (u1D70A)   lowercase omicron +
           π        \[*p]   u03C0 (u1D70B)   lowercase pi +
           ρ        \[*r]   u03C1 (u1D70C)   lowercase rho +
           σ        \[*s]   u03C3 (u1D70E)   lowercase sigma +
           τ        \[*t]   u03C4 (u1D70F)   lowercase tau +
           υ        \[*u]   u03C5 (u1D710)   lowercase upsilon +
           ϕ        \[*f]   u03D5 (u1D717)   lowercase phi +
           χ        \[*x]   u03C7 (u1D712)   lowercase chi +
           ψ        \[*q]   u03C8 (u1D713)   lowercase psi +
           ω        \[*w]   u03C9 (u1D714)   lowercase omega +
    
           ϵ        \[+e]   u03F5 (u1D716)   variant epsilon (lunate)
           ϑ        \[+h]   u03D1 (u1D717)   variant theta (cursive form)
           ϖ        \[+p]   u03D6 (u1D717)   variant pi (similar to omega)
           φ        \[+f]   u03C6 (u1D71B)   variant phi (curly shape)
           ς        \[ts]   u03C2 (u1D70D)   terminal lowercase sigma +
    
       **Playing card symbols**
           Output   Input   Unicode   Notes
           ───────────────────────────────────────────────────────────────────
           ♣        \[CL]   u2663     solid club suit
           ♠        \[SP]   u2660     solid spade suit
           ♥        \[HE]   u2665     solid heart suit
           ♦        \[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
           retain their accustomed 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                   │
                │ ! $ % & ( ) ‘ ’ * + - . , / : ; = ? [ ] │           │
                │ • □ — ‐ _ ¼ ½ ¾ ° † ′ ¢ ® ©                         │
                └─────────────────────────────────────────────────────┘
    
           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.
    
             ┌───────────────────────────────────────────────────────────┐
             │ _α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ σ ς τ υ ϕ χ ψ ω_         │
             │ Γ Δ Θ Λ Ξ Π Σ Υ Φ Ψ Ω                                     │
             │ " ´ \ ^ _ ` ~ / < > { } # @ + − = ∗                       │
             │ ≥ ≤ ≡ ≈ ∼ ≠ ↑ ↓ ← → × ÷ ± ∞ ∂ ∇ ¬ ∫ ∝ √ ‾ ∪ ∩ ⊂ ⊃ ⊆ ⊇ ∅ ∈ │
             │ § ‡ ☜ ☞ | ○ ⎧ ⎩ ⎫ ⎭ ⎨ ⎬ ⎪ ⌊ ⌋ ⌈ ⌉                         │
             └───────────────────────────────────────────────────────────┘
    
           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_.
    
           _/usr/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.
    
           _/usr/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)
    


* * *