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+'\" t
+.TH groff_char 7 "16 October 2023" "groff 1.23.0"
+.SH Name
+groff_char \- GNU
+.I roff
+special character and glyph repertoire
+.
+.
+.\" ====================================================================
+.\" Legal Terms
+.\" ====================================================================
+.\"
+.\" Copyright (C) 1989-2023 Free Software Foundation, Inc.
+.\"
+.\" This file is part of groff (GNU roff), which is a free software
+.\" project.
+.\"
+.\" You can redistribute it and/or modify it under the terms of the GNU
+.\" General Public License as published by the Free Software Foundation,
+.\" either version 2 of the License, or (at your option) any later
+.\" version.
+.\"
+.\" You should have received a copy of the GNU General Public License
+.\" along with this program.
+.\"
+.\" If not, see <http://www.gnu.org/licenses/gpl-2.0.html>.
+.
+.
+.\" Save and disable compatibility mode (for, e.g., Solaris 10/11).
+.do nr *groff_groff_char_7_man_C \n[.cp]
+.cp 0
+.
+.\" Define fallback for groff 1.23's MR macro if the system lacks it.
+.nr do-fallback 0
+.if !\n(.f .nr do-fallback 1 \" mandoc
+.if \n(.g .if !d MR .nr do-fallback 1 \" older groff
+.if !\n(.g .nr do-fallback 1 \" non-groff *roff
+.if \n[do-fallback] \{\
+. de MR
+. ie \\n(.$=1 \
+. I \%\\$1
+. el \
+. IR \%\\$1 (\\$2)\\$3
+. .
+.\}
+.rr do-fallback
+.
+.
+.\" ====================================================================
+.SH Description
+.\" ====================================================================
+.
+The GNU
+.I roff
+typesetting system has a large glyph repertoire suitable for production
+of varied literary,
+professional,
+technical,
+and mathematical documents.
+.
+.I groff
+works with
+.I characters;
+an output device renders
+.I glyphs.
+.
+.IR groff 's
+input character set is restricted to that defined by the standards
+ISO Latin-1
+(ISO 8859-1)
+and CCSID \[lq]code page\[rq] 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,
+.\" Yes, a subset, albeit a permutation as well in the cp1047 case.
+which has only 94 visible,
+printable code points.
+.\" In groff, 0x20 SP is mapped to a space node, not a glyph node, and
+.\" all kinds of special behavior attaches to such nodes, so we count
+.\" only to 94 and not 95 as is often done in other ASCII contexts.
+In
+.I groff,
+these are termed
+.I "ordinary characters."
+.
+Often,
+many more are desired in output.
+.
+.
+.P
+AT&T
+.I troff
+in the 1970s faced a similar problem:
+the available typesetter's glyph repertoire differed from that of the
+computers that controlled it.
+.
+.IR troff 's \" AT&T
+solution was a form of escape sequence known as a
+.I 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
+.B \e(aa
+encoded an acute accent and
+.B \e(sc
+a section sign.
+.
+.
+.P
+.I groff
+has lifted historical
+.I roff
+limitations on special character name lengths,
+but recognizes and retains compatibility with the historical names.
+.
+.I groff
+expands the lexicon of glyphs available by name and permits users to
+define their own special character escape sequences with the
+.B char
+request.
+.
+Special character names are
+.I groff
+identifiers;
+see section \[lq]Identifiers\[rq] in
+.MR groff 7 .
+.
+Our discussion uses the terms \[lq]glyph name\[rq] and \[lq]special
+character name\[rq] interchangeably;
+we assume no character translations or redefinitions.
+.
+.
+.P
+This document lists all of the glyph names predefined by
+.IR 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
+.B \*[.T]
+using font
+.BR \n[.fn] .
+.
+.
+.P
+A few escape sequences that are not
+.I groff
+special characters also produce glyphs;
+these exist for syntactical or historical reasons.
+.
+.BR \e\[aq] ,
+.BR \e\[ga] ,
+.BR \e\- ,
+and
+.B \e_
+are translated on input to the special character escape sequences
+.BR \e[aa] ,
+.BR \e[ga] ,
+.BR \e[\-] ,
+and
+.BR \e[ul] ,
+respectively.
+.
+Others include
+.BR \e\e ,
+.B \e.\&
+(backslash-dot),
+and
+.BR \ee ;
+see
+.MR groff 7 .
+.
+A small number of special characters represent glyphs that are not
+encoded in Unicode;
+examples include the baseline rule
+.B \e[ru]
+and the Bell System logo
+.B \e[bs].
+.
+.
+.P
+In
+.IR groff ,
+you can test output device support for any character
+(ordinary or special)
+with the conditional expression operator
+.RB \[lq] c \[rq].
+.
+.RS
+.\" https://www.bell-labs.com/usr/dmr/www/ ("In 1984, ...")
+.EX
+\&.ie c \e[bs] \e{Welcome to the \e[bs] Bell System;
+did you get the Wehrmacht helmet or the Death Star?\e}
+\&.el No Bell System logo.
+.EE
+.RE
+.
+.
+.P
+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 (\[lq]Unicode\[rq])
+character encoding standards as \[lq]ISO\[rq] systems,
+and those employing IBM code page 1047 as \[lq]EBCDIC\[rq] systems.
+.
+That said,
+EBCDIC systems that support
+.I groff
+are known to also support UTF-8.
+.
+.
+.P
+While
+.I groff
+accepts eight-bit encoded input,
+not all such code points are valid as input.
+.
+.\" src/libs/libgroff/invalid.cpp
+On ISO platforms,
+character codes
+0,
+11,
+13\[en]31,
+and
+128\[en]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\[en]9,
+11,
+13\[en]20,
+23\[en]31,
+and
+48\[en]63
+are invalid.
+.
+Some of these code points are used by
+.I groff
+for internal purposes,
+which is one reason it does not support UTF-8 natively.
+.
+.
+.\" ====================================================================
+.SS "Fundamental character set"
+.\" ====================================================================
+.
+The ordinary characters catalogued above,
+plus the space,
+tab,
+newline,
+and leader (Control+A),
+form the fundamental character
+set for
+.I 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\[en]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
+.I troff
+was implemented.
+.
+On EBCDIC systems,
+printable characters are in the range 66\[en]201 and 203\[en]254;
+those without counterparts in the ISO range 33\[en]126 are discussed
+in the next subsection.
+.\" From this point, do not talk about numerical character assignments.
+.
+.
+.P
+All of the following characters map to glyphs as you would expect.
+.
+.TS
+center box;
+Lf(CR).
+! # $ % & ( ) * + , . / 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 { | }
+.TE
+.\" The bottom border of that box is practically kissin' the tittles.
+.if t .sp 0.2v
+.
+The remaining ordinary characters surprise computing professionals and
+others intimately familiar with the ISO character encodings.
+.
+The developers of AT&T
+.I 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 (\[lq]ASCII\[rq]),
+deliberately supported semantic ambiguity at some code points,
+and outright substitution at several others,
+to suit the localization demands of various national standards bodies.
+.
+.
+.P
+The table below presents the seven exceptional code points
+with their typical keycap engravings,
+their glyph mappings and semantics in
+.I 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
+.I roff
+language also uses it to quote macro arguments,
+.I 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
+.I troff
+required in that context.
+.
+(Some requests,
+like
+.BR ds ,
+also treat
+.B \[dq]
+non-literally.)
+.
+Furthermore,
+not all of the special character escape sequences are portable to AT&T
+.I troff
+and all of its descendants;
+these
+.I groff
+extensions are presented using its special character form
+.BR \[rs][] ,
+whereas portable special character escape sequences are shown in the
+traditional
+.B \[rs](
+form.
+.
+.B \[rs]\-
+and
+.B \[rs]e
+are portable to all known
+.IR troff s.
+.
+.B \[rs]e
+means \[lq]the glyph of the current escape character\[rq];
+it therefore can produce unexpected output if the
+.B ec
+request is used.
+.
+On devices with a limited glyph repertoire,
+glyphs in the \[lq]keycap\[rq] and \[lq]appearance\[rq] columns on the
+same row of the table may look identical;
+except for the neutral double quote,
+this will
+.I not
+be the case on more-capable devices.
+.
+Review your document using as many different output devices as possible.
+.
+.
+.P
+.TS
+center box;
+L L L.
+Keycap Appearance and meaning Special character and meaning
+_
+" " neutral double quote \f[CR]\[rs][dq]\f[] neutral double quote
+\[aq] \[cq] closing single quote \f[CR]\[rs][aq]\f[] neutral apostrophe
+\- - hyphen \f[CR]\[rs]\-\f[] or \f[CR]\[rs][\-]\f[] minus sign/Unix dash
+\[rs] (escape character) \f[CR]\[rs]e\f[] or \f[CR]\[rs][rs]\f[] reverse solidus
+\[ha] \[u02C6] modifier circumflex \f[CR]\[rs](ha\f[] circumflex/caret/\[lq]hat\[rq]
+\[ga] \[oq] opening single quote \f[CR]\[rs](ga\f[] grave accent
+\[ti] \[u02DC] modifier tilde \f[CR]\[rs](ti\f[] tilde
+.TE
+.
+.
+.P
+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
+.I roff
+systems,
+use the
+.RB \[lq] \- \[rq]
+character in input outside an escape sequence
+.I only
+to mean a hyphen,
+as in the phrase \[lq]long-term\[rq].
+.
+For a minus sign in running text or a Unix command-line option dash,
+use
+.B \[rs]\-
+(or
+.B \[rs][\-]
+in
+.I groff
+if you find it helps the clarity of the source document).
+.
+(Another minus sign,
+for use in mathematical equations,
+is available as
+.BR \[rs][mi] ).
+.
+AT&T
+.I troff
+supported em-dashes as
+.BR \[rs](em ,
+as does
+.IR groff .
+.
+.
+.P
+The special character escape sequence for the apostrophe as a neutral
+single quote is typically needed only in technical content;
+typing words like \[lq]can't\[rq] and \[lq]Anne's\[rq] 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
+.I 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
+.I troff
+defined no special characters for quotation marks or the apostrophe.
+.
+Repeated single quotes
+(\[oq]\[oq]thus\[cq]\[cq])
+will be visually distinguishable from double quotes
+(\[lq]thus\[rq])
+on terminal devices,
+and perhaps on others
+(depending on the font selected).
+.
+.TS
+tab(@) center box;
+L L.
+AT&T \f[I]troff\f[] input@recommended \f[I]groff\f[] input
+_
+.T&
+Lf(CR) Lf(CR).
+A Winter\[aq]s Tale@A Winter\[aq]s Tale
+\[ga]U.K.\& outer quotes\[aq]@\[rs][oq]U.K.\& outer quotes\[rs][cq]
+\[ga]U.K.\& \[ga]\[ga]inner\[aq]\[aq] quotes\[aq]\
+@\[rs][oq]U.K.\& \[rs][lq]inner\[rs][rq] quotes\[rs][cq]
+\[ga]\[ga]U.S.\& outer quotes\[aq]\[aq]\
+@\[rs][lq]U.S.\& outer quotes\[rs][rq]
+\[ga]\[ga]U.S.\& \[ga]inner\[aq] quotes\[aq]\[aq]\
+@\[rs][lq]U.S.\& \[rs][oq]inner\[rs][cq] quotes\[rs][rq]
+.TE
+.\" Keep bottom border of box from sitting on the ascenders below.
+.if t .sp 0.2v
+.
+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).
+.
+.
+.P
+Using Unicode basic Latin characters to compose boxes and lines is
+ill-advised.
+.
+.I roff
+systems have special characters for drawing horizontal and vertical
+lines;
+see subsection \[lq]Rules and lines\[rq] below.
+.
+Preprocessors like
+.MR \%tbl 1
+and
+.MR \%pic 1
+draw boxes and will produce the best possible output for the device,
+falling back to basic Latin glyphs only when necessary.
+.
+.
+.\" ====================================================================
+.SS "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 \[lq]C1 controls\[rq]
+(control characters)
+and the \[lq]Latin-1 supplement\[rq].
+.
+The C1 controls are neither printable nor usable as
+.I groff
+input.
+.
+.
+.P
+Two Latin-1 supplement characters are handled specially on input.
+.
+.I \%troff
+never produces them as output.
+.
+.
+.TP
+NBSP
+encodes a no-break space;
+it is mapped to
+.BR \[rs]\[ti] ,
+the adjustable non-breaking space escape sequence.
+.
+.
+.TP
+SHY
+encodes a soft hyphen;
+it is mapped to
+.BR \[rs]% ,
+the hyphenation control escape sequence.
+.
+.
+.P
+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
+.I 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.
+.
+.
+.P
+.TS
+L2 Lf(CR)1 L L2 Lf(CR)1 L.
+\[r!] \e[r!] inverted exclamation mark \[~N] \e[\[ti]N] N tilde
+\[ct] \e[ct] cent sign \[`O] \e[\[ga]O] O grave
+\[Po] \e[Po] pound sign \['O] \e[\[aq]O] O acute
+\[Cs] \e[Cs] currency sign \[^O] \e[\[ha]O] O circumflex
+\[Ye] \e[Ye] yen sign \[~O] \e[\[ti]O] O tilde
+\[bb] \e[bb] broken bar \[:O] \e[:O] O dieresis
+\[sc] \e[sc] section sign \[mu] \e[mu] multiplication sign
+\[ad] \e[ad] dieresis accent \[/O] \e[/O] O slash
+\[co] \e[co] copyright sign \[`U] \e[\[ga]U] U grave
+\[Of] \e[Of] feminine ordinal indicator \['U] \e[\[aq]U] U acute
+\[Fo] \e[Fo] left double chevron \[^U] \e[\[ha]U] U circumflex
+\[no] \e[no] logical not \[:U] \e[:U] U dieresis
+\[rg] \e[rg] registered sign \['Y] \e[\[aq]Y] Y acute
+\[a-] \e[a\-] macron accent \[TP] \e[TP] uppercase thorn
+\[de] \e[de] degree sign \[ss] \e[ss] lowercase sharp s
+\[+-] \e[+\-] plus-minus \[`a] \e[\[ga]a] a grave
+\[S2] \e[S2] superscript two \['a] \e[\[aq]a] a acute
+\[S3] \e[S3] superscript three \[^a] \e[\[ha]a] a circumflex
+\[aa] \e[aa] acute accent \[~a] \e[\[ti]a] a tilde
+\[mc] \e[mc] micro sign \[:a] \e[:a] a dieresis
+\[ps] \e[ps] pilcrow sign \[oa] \e[oa] a ring
+\[pc] \e[pc] centered period \[ae] \e[ae] ae ligature
+\[ac] \e[ac] cedilla accent \[,c] \e[,c] c cedilla
+\[S1] \e[S1] superscript one \[`e] \e[\[ga]e] e grave
+\[Om] \e[Om] masculine ordinal indicator \['e] \e[\[aq]e] e acute
+\[Fc] \e[Fc] right double chevron \[^e] \e[\[ha]e] e circumflex
+\[14] \e[14] one quarter symbol \[:e] \e[:e] e dieresis
+\[12] \e[12] one half symbol \[`i] \e[\[ga]i] i grave
+\[34] \e[34] three quarters symbol \['i] \e[\[aq]i] e acute
+\[r?] \e[r?] inverted question mark \[^i] \e[\[ha]i] i circumflex
+\[`A] \e[\[ga]A] A grave \[:i] \e[:i] i dieresis
+\['A] \e[\[aq]A] A acute \[Sd] \e[Sd] lowercase eth
+\[^A] \e[\[ha]A] A circumflex \[~n] \e[\[ti]n] n tilde
+\[~A] \e[\[ti]A] A tilde \[`o] \e[\[ga]o] o grave
+\[:A] \e[:A] A dieresis \['o] \e[\[aq]o] o acute
+\[oA] \e[oA] A ring \[^o] \e[\[ha]o] o circumflex
+\[AE] \e[AE] AE ligature \[~o] \e[\[ti]o] o tilde
+\[,C] \e[,C] C cedilla \[:o] \e[:o] o dieresis
+\[`E] \e[\[ga]E] E grave \[di] \e[di] division sign
+\['E] \e[\[aq]E] E acute \[/o] \e[/o] o slash
+\[^E] \e[\[ha]E] E circumflex \[`u] \e[\[ga]u] u grave
+\[:E] \e[:E] E dieresis \['u] \e[\[aq]u] u acute
+\[`I] \e[\[ga]I] I grave \[^u] \e[\[ha]u] u circumflex
+\['I] \e[\[aq]I] I acute \[:u] \e[:u] u dieresis
+\[^I] \e[\[ha]I] I circumflex \['y] \e[\[aq]y] y acute
+\[:I] \e[:I] I dieresis \[Tp] \e[Tp] lowercase thorn
+\[-D] \e[\-D] uppercase eth \[:y] \e[:y] y dieresis
+.TE
+.
+.
+.\" ====================================================================
+.SS "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
+.I troff \" AT&T
+special character escape sequences.
+.
+Predefined glyph names use only characters in the basic Latin
+repertoire.
+.
+.
+.TP
+.BI \[rs]( gl
+is a special character escape sequence for the glyph with the
+two-character name
+.IR gl .
+.
+This is the original syntax form supported by AT&T
+.IR troff .
+.
+The acute accent,
+.BR \[rs](aa ,
+is an example.
+.
+.
+.TP
+.BI \[rs]C\[aq] glyph-name \[aq]
+is a special character escape sequence for
+.IR glyph-name ,
+which can be of arbitrary length.
+.
+The delimiter,
+shown here as a neutral apostrophe,
+can be any character not occurring in
+.IR glyph-name .
+.
+This syntax form was introduced in later versions of AT&T
+device-independent
+.IR troff . \" AT&T
+.
+The foregoing acute accent example can be expressed
+as
+.BR \[rs]C\[aq]aa\[aq] .
+.
+.
+.TP
+.BI \[rs][ glyph-name ]
+is a special character escape sequence for
+.IR glyph-name ,
+which can be of arbitrary length but must not contain a closing square
+bracket
+.RB \[lq] ] \[rq].
+.
+(No glyph names predefined by
+.I groff
+employ
+.RB \[lq] ] \[rq].)
+.
+The foregoing acute accent example can be expressed in
+.I groff
+as
+.BR \[rs][aa] .
+.
+.
+.P
+.BI \[rs]C\[aq] c \[aq]
+and
+.BI \[rs][ c ]
+are not synonyms for the ordinary character
+.RI \[lq] c \[rq],
+but request the special character named
+.RB \[lq] \[rs] \c
+.IR c \[rq].
+.
+For example,
+.RB \[lq] \[rs][a] \[rq]
+is not \[lq]a\[rq],
+but rather a special character with the internal glyph name
+(used in font description files and diagnostic messages)
+.BR \[rs]a ,
+which is typically undefined.
+.
+The only such glyph name
+.I groff
+predefines is the minus sign,
+which can therefore be accessed as
+.B \[rs]C\[aq]\-\[aq]
+or
+.BR \[rs][\-] .
+.
+.
+.TP
+.BI \[rs][ "base-char composite-1 composite-2"\~\c
+\&.\|.\|.\~\c
+.IB composite-n ]
+is a composite glyph.
+.
+Glyphs like a lowercase \[lq]e\[rq] with an acute accent,
+as in the word \[lq]caf\[e aa]\[rq],
+can be expressed as
+.BR "\[rs][e aa]" .
+.
+See subsection \[lq]Accents\[rq] below for a table of combining glyph
+names.
+.
+.
+.P
+Unicode encodes far more characters than
+.I 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
+.I "ad hoc"
+with the
+.B char
+request;
+see
+.MR groff 7 .
+.
+.
+.TP
+.BI \[rs][u nnnn\c
+.RI [ n\c
+.RI [ n ]]\c
+.B ]
+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,
+.B \[rs][u02DA]
+accesses the (spacing) ring accent,
+producing \[lq]\[u02DA]\[rq].
+.
+.
+.\" Use "GNU troff" in this paragraph because the contrast with AT&T
+.\" troff, which antedated Unicode, is important, and that contrast is
+.\" obscured with the default empty command prefix on "troff".
+.P
+Unicode code points can be composed as well;
+when they are,
+GNU
+.I troff \" GNU
+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
+.I troff \" GNU
+that accepts UTF-8 input directly.)
+.
+.
+Thus,
+GNU
+.I troff \" GNU
+accepts
+.RB \[lq]caf \[rs][\[aq]e] \[rq],
+.RB \[lq]caf \[rs][e\~aa] \[rq],
+and
+.RB \[lq]caf \[rs][u0065_0301] \[rq],
+as ways to input \[lq]caf\['e]\[rq].
+.
+(Due to its legacy 8-bit encoding compatibility,
+at present it also accepts
+.RB \[lq]caf \[rs][u00E9] \[rq]
+on ISO Latin-1 systems.)
+.
+.
+.TP
+.BI \[rs][u base-char\c
+[\c
+.BI _ combining-component\c
+].\|.\|.]
+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
+.RB ( _ )
+separating each component.
+.
+Thus,
+.B \[rs][u006E_0303]
+produces \[lq]\[u006E_0303]\[rq].
+.
+.
+.TP
+.BI \[rs][char nnn ]
+expresses an eight-bit code point where
+.I 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
+.B trin
+request in macro files loaded by
+.MR grotty 1 .
+.
+.
+.\" ====================================================================
+.SH "Glyph tables"
+.\" ====================================================================
+.
+In this section,
+.IR groff 's
+glyph name repertoire is presented in tabular form.
+.
+The meanings of the columns are as follows.
+.
+.
+.TP 8n
+.B 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),
+.I groff
+attempts reasonable equivalency on all output devices.
+.
+.
+.TP
+.B Input
+shows the
+.I groff
+character
+(ordinary or special)
+that normally produces the glyph.
+.
+Some code points have multiple glyph names.
+.
+.
+.TP
+.B Unicode
+is the code point notation for the glyph or combining glyph sequence as
+described in subsection \[lq]Special character escape forms\[rq] above.
+.
+It corresponds to the standard notation for Unicode short identifiers
+such that
+.IR groff 's
+.BI u nnnn
+is equivalent to Unicode's
+.RI U+ nnnn .
+.\" And thereby hangs a tale...
+.\" https://unicode.org/mail-arch/unicode-ml/y2005-m11/0060.html
+.
+.
+.TP
+.B Notes
+describes the glyph,
+elucidating the mnemonic value of the glyph name where possible.
+.
+.
+.IP
+A plus sign \[lq]+\[rq] indicates that the glyph name appears in the
+AT&T
+.I troff
+user's manual,
+CSTR\~#54
+(1992 revision).
+.
+When using the AT&T special character syntax
+.BI \[rs]( xx\c
+, widespread portability can be expected from such names.
+.
+.
+.IP
+Entries marked with \[lq]***\[rq] denote glyphs used for mathematical
+purposes.
+.
+On typesetting devices,
+such glyphs are typically drawn from a
+.I special
+font
+(see
+.MR 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 \[lq]text
+variants\[rq],
+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
+(\[lq]Logical symbols\[rq] and \[lq]Mathematical symbols\[rq]).
+.
+.
+.\" ====================================================================
+.SS "Basic Latin"
+.\" ====================================================================
+.
+Apart from basic Latin characters with special mappings,
+described in subsection \[lq]Fundamental character set\[rq] above,
+a few others in that range have special character glyph names.
+.
+.\" XXX: I surmise that...
+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.
+.
+.
+.P
+The vertical bar is overloaded;
+the
+.B \[rs][ba]
+and
+.B \[rs][or]
+escape sequences may render differently.
+.
+See subsection \[lq]Mathematical symbols\[rq] below for special variants
+of the plus,
+minus,
+and equals
+signs normally drawn from this range.
+.
+.
+.P
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[dq] \e[dq] u0022 neutral double quote
+\[sh] \e[sh] u0023 number sign
+\[Do] \e[Do] u0024 dollar sign
+\[aq] \e[aq] u0027 apostrophe, neutral single quote
+\[sl] \e[sl] u002F slash, solidus +
+\[at] \e[at] u0040 at sign
+\[lB] \e[lB] u005B left square bracket
+\[rs] \e[rs] u005C reverse solidus
+\[rB] \e[rB] u005D right square bracket
+\[ha] \e[ha] u005E circumflex, caret, \[lq]hat\[rq]
+\[lC] \e[lC] u007B left brace
+| | u007C bar
+\[ba] \e[ba] u007C bar
+\[or] \e[or] u007C bitwise or +
+\[rC] \e[rC] u007D right brace
+\[ti] \e[ti] u007E tilde
+.TE
+.
+.
+.\" ====================================================================
+.SS "Supplementary Latin letters"
+.\" ====================================================================
+.
+Historically,
+.B \[rs][ss]
+could be considered a ligature of \[lq]sz\[rq].
+.
+An uppercase form is available as
+.BR \[rs][u1E9E] ,
+but in the German language it is of specialized use;
+\[ss] does
+.I not
+normally uppercase-transform to it,
+but rather to \[lq]SS\[rq].
+.
+\[lq]Lowercase f with hook\[rq] is also used as a function symbol;
+see subsection \[lq]Mathematical symbols\[rq] below.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[-D] \e[\-D] u00D0 uppercase eth
+\[Sd] \e[Sd] u00F0 lowercase eth
+\[TP] \e[TP] u00DE uppercase thorn
+\[Tp] \e[Tp] u00FE lowercase thorn
+\[ss] \e[ss] u00DF lowercase sharp s
+\[.i] \e[.i] u0131 i without tittle
+\[.j] \e[.j] u0237 j without tittle
+\[Fn] \e[Fn] u0192 lowercase f with hook, function
+\[/L] \e[/L] u0141 L with stroke
+\[/l] \e[/l] u0142 l with stroke
+\[/O] \e[/O] u00D8 O with stroke
+\[/o] \e[/o] u00F8 o with stroke
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS "Ligatures and digraphs"
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[ff] \e[ff] u0066_0066 ff ligature +
+\[fi] \e[fi] u0066_0069 fi ligature +
+\[fl] \e[fl] u0066_006C fl ligature +
+\[Fi] \e[Fi] u0066_0066_0069 ffi ligature +
+\[Fl] \e[Fl] u0066_0066_006C ffl ligature +
+\[AE] \e[AE] u00C6 AE ligature
+\[ae] \e[ae] u00E6 ae ligature
+\[OE] \e[OE] u0152 OE ligature
+\[oe] \e[oe] u0153 oe ligature
+\[IJ] \e[IJ] u0132 IJ digraph
+\[ij] \e[ij] u0133 ij digraph
+.TE
+.
+.
+.\" ====================================================================
+.SS Accents
+.\" ====================================================================
+.
+Normally,
+the formatting of a special character advances the drawing position as
+an ordinary character does.
+.
+.IR groff 's
+.B composite
+request designates a special character as combining.
+.
+The
+.I composite.tmac
+macro file,
+loaded automatically by the default
+.IR 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
+.RB \[lq] "caf\[rs][e aa]" \[rq]
+and
+.RB \[lq] "caf\[rs][aa]e" \[rq]).
+.
+.
+.P
+.if t .ne 3v
+.if n .ne 4v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[a"] \e[a"] u030B (u02DD) double acute accent
+\[a-] \e[a\-] u0304 (u00AF) macron accent
+\[a.] \e[a.] u0307 (u02D9) dot accent
+\[a^] \e[a\[ha]] u0302 (u005E) circumflex accent
+\[aa] \e[aa] u0301 (u00B4) acute accent +
+\[ga] \e[ga] u0300 (u0060) grave accent +
+\[ab] \e[ab] u0306 (u02D8) breve accent
+\[ac] \e[ac] u0327 (u00B8) cedilla accent
+\[ad] \e[ad] u0308 (u00A8) dieresis accent
+\[ah] \e[ah] u030C (u02C7) caron accent
+\[ao] \e[ao] u030A (u02DA) ring accent
+\[a~] \e[a\[ti]] u0303 (u007E) tilde accent
+\[ho] \e[ho] u0328 (u02DB) hook accent
+.TE
+.
+.
+.\" ====================================================================
+.SS "Accented characters"
+.\" ====================================================================
+.
+All of these glyphs can be composed using combining glyph names as
+described in subsection \[lq]Special character escape forms\[rq] above;
+the names below are short aliases for convenience.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\['A] \e[\[aq]A] u0041_0301 A acute
+\['C] \e[\[aq]C] u0043_0301 C acute
+\['E] \e[\[aq]E] u0045_0301 E acute
+\['I] \e[\[aq]I] u0049_0301 I acute
+\['O] \e[\[aq]O] u004F_0301 O acute
+\['U] \e[\[aq]U] u0055_0301 U acute
+\['Y] \e[\[aq]Y] u0059_0301 Y acute
+\['a] \e[\[aq]a] u0061_0301 a acute
+\['c] \e[\[aq]c] u0063_0301 c acute
+\['e] \e[\[aq]e] u0065_0301 e acute
+\['i] \e[\[aq]i] u0069_0301 i acute
+\['o] \e[\[aq]o] u006F_0301 o acute
+\['u] \e[\[aq]u] u0075_0301 u acute
+\['y] \e[\[aq]y] u0079_0301 y acute
+
+\[:A] \e[:A] u0041_0308 A dieresis
+\[:E] \e[:E] u0045_0308 E dieresis
+\[:I] \e[:I] u0049_0308 I dieresis
+\[:O] \e[:O] u004F_0308 O dieresis
+\[:U] \e[:U] u0055_0308 U dieresis
+\[:Y] \e[:Y] u0059_0308 Y dieresis
+\[:a] \e[:a] u0061_0308 a dieresis
+\[:e] \e[:e] u0065_0308 e dieresis
+\[:i] \e[:i] u0069_0308 i dieresis
+\[:o] \e[:o] u006F_0308 o dieresis
+\[:u] \e[:u] u0075_0308 u dieresis
+\[:y] \e[:y] u0079_0308 y dieresis
+
+\[^A] \e[\[ha]A] u0041_0302 A circumflex
+\[^E] \e[\[ha]E] u0045_0302 E circumflex
+\[^I] \e[\[ha]I] u0049_0302 I circumflex
+\[^O] \e[\[ha]O] u004F_0302 O circumflex
+\[^U] \e[\[ha]U] u0055_0302 U circumflex
+\[^a] \e[\[ha]a] u0061_0302 a circumflex
+\[^e] \e[\[ha]e] u0065_0302 e circumflex
+\[^i] \e[\[ha]i] u0069_0302 i circumflex
+\[^o] \e[\[ha]o] u006F_0302 o circumflex
+\[^u] \e[\[ha]u] u0075_0302 u circumflex
+
+\[`A] \e[\[ga]A] u0041_0300 A grave
+\[`E] \e[\[ga]E] u0045_0300 E grave
+\[`I] \e[\[ga]I] u0049_0300 I grave
+\[`O] \e[\[ga]O] u004F_0300 O grave
+\[`U] \e[\[ga]U] u0055_0300 U grave
+\[`a] \e[\[ga]a] u0061_0300 a grave
+\[`e] \e[\[ga]e] u0065_0300 e grave
+\[`i] \e[\[ga]i] u0069_0300 i grave
+\[`o] \e[\[ga]o] u006F_0300 o grave
+\[`u] \e[\[ga]u] u0075_0300 u grave
+
+\[~A] \e[\[ti]A] u0041_0303 A tilde
+\[~N] \e[\[ti]N] u004E_0303 N tilde
+\[~O] \e[\[ti]O] u004F_0303 O tilde
+\[~a] \e[\[ti]a] u0061_0303 a tilde
+\[~n] \e[\[ti]n] u006E_0303 n tilde
+\[~o] \e[\[ti]o] u006F_0303 o tilde
+
+\[vS] \e[vS] u0053_030C S caron
+\[vs] \e[vs] u0073_030C s caron
+\[vZ] \e[vZ] u005A_030C Z caron
+\[vz] \e[vz] u007A_030C z caron
+
+\[,C] \e[,C] u0043_0327 C cedilla
+\[,c] \e[,c] u0063_0327 c cedilla
+
+\[oA] \e[oA] u0041_030A A ring
+\[oa] \e[oa] u0061_030A a ring
+.TE
+.
+.
+.\" ====================================================================
+.SS "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 \[lq]Fundamental character set\[rq] above.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[Bq] \e[Bq] u201E low double comma quote
+\[bq] \e[bq] u201A low single comma quote
+\[lq] \e[lq] u201C left double quote
+\[rq] \e[rq] u201D right double quote
+\[oq] \e[oq] u2018 single opening (left) quote
+\[cq] \e[cq] u2019 single closing (right) quote
+\[aq] \e[aq] u0027 apostrophe, neutral single quote
+\[dq] " u0022 neutral double quote
+\[dq] \e[dq] u0022 neutral double quote
+\[Fo] \e[Fo] u00AB left double chevron
+\[Fc] \e[Fc] u00BB right double chevron
+\[fo] \e[fo] u2039 left single chevron
+\[fc] \e[fc] u203A right single chevron
+.TE
+.
+.
+.\" ====================================================================
+.SS Punctuation
+.\" ====================================================================
+.
+The Unicode name for U+00B7 is \[lq]middle dot\[rq],
+which is unfortunately confusable with the
+.I groff
+mnemonic for the visually similar but semantically distinct
+multiplication dot;
+see subsection \[lq]Mathematical symbols\[rq] below.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[r!] \e[r!] u00A1 inverted exclamation mark
+\[r?] \e[r?] u00BF inverted question mark
+\[pc] \e[pc] u00B7 centered period
+\[em] \e[em] u2014 em-dash +
+\[en] \e[en] u2013 en-dash
+\[hy] \e[hy] u2010 hyphen +
+.TE
+.
+.
+.\" ====================================================================
+.SS 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
+.I not
+font-invariant;
+.I groff
+maps them rather arbitrarily to U+23AA
+(\[lq]curly bracket extension\[rq]).
+.
+In AT&T
+.IR troff ,
+only one glyph was available to vertically extend
+brackets,
+braces,
+and
+parentheses:
+.BR \[rs](bv .
+.
+.
+.
+.P
+Not all devices supply bracket pieces that can be piled up with
+.B \[rs]b
+due to the restrictions of the escape's piling algorithm.
+.
+A general solution to build brackets out of pieces is the following
+macro:
+.
+.
+.RS
+.EX
+\&.\e" Make a pile centered vertically 0.5em above the baseline.
+\&.\e" The first argument is placed at the top.
+\&.\e" The pile is returned in string \[aq]pile\[aq].
+\&.eo
+\&.de pile\-make
+\&.\& nr pile\-wd 0
+\&.\& nr pile\-ht 0
+\&.\& ds pile\-args
+\&.\&
+\&.\& nr pile\-# \en[.$]
+\&.\& while \en[pile\-#] \e{\e
+\&.\& nr pile\-wd (\en[pile\-wd] >? \ew\[aq]\e$[\en[pile\-#]]\[aq])
+\&.\& nr pile\-ht +(\en[rst] \- \en[rsb])
+\&.\& as pile\-args \ev\[aq]\en[rsb]u\[aq]\e"
+\&.\& as pile\-args \eZ\[aq]\e$[\en[pile\-#]]\[aq]\e"
+\&.\& as pile\-args \ev\[aq]\-\en[rst]u\[aq]\e"
+\&.\& nr pile\-# \-1
+\&.\& \e}
+\&.\&
+\&.\& ds pile \ev\[aq](\-0.5m + (\en[pile\-ht]u / 2u))\[aq]\e"
+\&.\& as pile \e*[pile\-args]\e"
+\&.\& as pile \ev\[aq]((\en[pile\-ht]u / 2u) + 0.5m)\[aq]\e"
+\&.\& as pile \eh\[aq]\en[pile\-wd]u\[aq]\e"
+\&..
+\&.ec
+.EE
+.RE
+.
+.
+.P
+Another complication is the fact that some glyphs which represent
+bracket pieces in AT&T
+.I troff
+can be used for other mathematical symbols as well,
+for example
+.B \[rs](lf
+and
+.BR \[rs](rf ,
+which provide the floor operator.
+.
+Some output devices,
+such as
+.BR dvi ,
+don't unify such glyphs.
+.
+For this reason,
+the glyphs
+.BR \[rs][lf] ,
+.BR \[rs][rf] ,
+.BR \[rs][lc] ,
+and
+.B \[rs][rc]
+are not unified with similar-looking bracket pieces.
+.
+In
+.IR groff ,
+only glyphs with long names are guaranteed to pile up correctly for all
+devices\[em]provided those glyphs are available.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[lB] [ u005B left square bracket
+\[lB] \e[lB] u005B left square bracket
+\[rB] ] u005D right square bracket
+\[rB] \e[rB] u005D right square bracket
+\[lC] { u007B left brace
+\[lC] \e[lC] u007B left brace
+\[rC] } u007D right brace
+\[rC] \e[rC] u007D right brace
+\[la] \e[la] u27E8 left angle bracket
+\[ra] \e[ra] u27E9 right angle bracket
+\[bv] \e[bv] u23AA brace vertical extension + ***
+\[braceex] \e[braceex] u23AA brace vertical extension
+
+\[bracketlefttp] \e[bracketlefttp] u23A1 left square bracket top
+\[bracketleftex] \e[bracketleftex] u23A2 left square bracket extension
+\[bracketleftbt] \e[bracketleftbt] u23A3 left square bracket bottom
+
+\[bracketrighttp] \e[bracketrighttp] u23A4 right square bracket top
+\[bracketrightex] \e[bracketrightex] u23A5 right square bracket extension
+\[bracketrightbt] \e[bracketrightbt] u23A6 right square bracket bottom
+
+\[lt] \e[lt] u23A7 left brace top +
+\[lk] \e[lk] u23A8 left brace middle +
+\[lb] \e[lb] u23A9 left brace bottom +
+\[bracelefttp] \e[bracelefttp] u23A7 left brace top
+\[braceleftmid] \e[braceleftmid] u23A8 left brace middle
+\[braceleftbt] \e[braceleftbt] u23A9 left brace bottom
+\[braceleftex] \e[braceleftex] u23AA left brace extension
+
+\[rt] \e[rt] u23AB right brace top +
+\[rk] \e[rk] u23AC right brace middle +
+\[rb] \e[rb] u23AD right brace bottom +
+\[bracerighttp] \e[bracerighttp] u23AB right brace top
+\[bracerightmid] \e[bracerightmid] u23AC right brace middle
+\[bracerightbt] \e[bracerightbt] u23AD right brace bottom
+\[bracerightex] \e[bracerightex] u23AA right brace extension
+
+\[parenlefttp] \e[parenlefttp] u239B left parenthesis top
+\[parenleftex] \e[parenleftex] u239C left parenthesis extension
+\[parenleftbt] \e[parenleftbt] u239D left parenthesis bottom
+\[parenrighttp] \e[parenrighttp] u239E right parenthesis top
+\[parenrightex] \e[parenrightex] u239F right parenthesis extension
+\[parenrightbt] \e[parenrightbt] u23A0 right parenthesis bottom
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS Arrows
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[<-] \e[<\-] u2190 horizontal arrow left +
+\[->] \e[\->] u2192 horizontal arrow right +
+\[<>] \e[<>] u2194 bidirectional horizontal arrow
+\[da] \e[da] u2193 vertical arrow down +
+\[ua] \e[ua] u2191 vertical arrow up +
+\[va] \e[va] u2195 bidirectional vertical arrow
+\[lA] \e[lA] u21D0 horizontal double arrow left
+\[rA] \e[rA] u21D2 horizontal double arrow right
+\[hA] \e[hA] u21D4 bidirectional horizontal double arrow
+\[dA] \e[dA] u21D3 vertical double arrow down
+\[uA] \e[uA] u21D1 vertical double arrow up
+\[vA] \e[vA] u21D5 bidirectional vertical double arrow
+\[an] \e[an] u23AF horizontal arrow extension
+.TE
+.
+.
+.\" ====================================================================
+.SS "Rules and lines"
+.\" ====================================================================
+.
+On typesetting devices,
+the font-invariant glyphs
+(see subsection \[lq]Brackets\[rq] above)
+.BR \[rs][br] ,
+.BR \[rs][ul] ,
+and
+.B \[rs][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.
+.
+.
+.P
+The input character
+.B _
+always accesses the underscore glyph in a font;
+.\" unless one isn't available, but this seems to be only a theoretical
+.\" concern--what font doesn't support every ASCII codepoint these days?
+.BR \[rs][ul] ,
+by contrast,
+may be font-invariant on typesetting devices.
+.
+.
+.P
+The baseline rule
+.B \[rs][ru]
+is a font-invariant glyph,
+namely a rule of one-half em.
+.
+.
+.P
+In AT&T
+.IR troff , \" AT&T
+.B \[rs][rn]
+also served as a one\~en extension of the square root symbol.
+.
+.I groff
+favors
+.B \[rs][radicalex]
+for this purpose;
+see subsection \[lq]Mathematical symbols\[rq] below.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+| | u007C bar
+\[ba] \e[ba] u007C bar
+\[br] \e[br] u2502 box rule +
+\&_ \&_ u005F underscore, low line +
+\[ul] \e[ul] --- underrule +
+\[rn] \e[rn] u203E overline +
+\[ru] \e[ru] --- baseline rule +
+\[bb] \e[bb] u00A6 broken bar
+\[sl] / u002F slash, solidus +
+\[sl] \e[sl] u002F slash, solidus +
+\[rs] \e[rs] u005C reverse solidus
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS "Text markers"
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[ci] \e[ci] u25CB circle +
+\[bu] \e[bu] u2022 bullet +
+\[dg] \e[dg] u2020 dagger +
+\[dd] \e[dd] u2021 double dagger +
+\[lz] \e[lz] u25CA lozenge, diamond
+\[sq] \e[sq] u25A1 square +
+\[ps] \e[ps] u00B6 pilcrow sign
+\[sc] \e[sc] u00A7 section sign +
+\[lh] \e[lh] u261C hand pointing left +
+\[rh] \e[rh] u261E hand pointing right +
+\[at] @ u0040 at sign
+\[at] \e[at] u0040 at sign
+\[sh] # u0023 number sign
+\[sh] \e[sh] u0023 number sign
+\[CR] \e[CR] u21B5 carriage return
+\[OK] \e[OK] u2713 check mark
+.TE
+.
+.\" ====================================================================
+.SS "Legal symbols"
+.\" ====================================================================
+.
+The Bell System logo is not supported in
+.IR groff .
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[co] \e[co] u00A9 copyright sign +
+\[rg] \e[rg] u00AE registered sign +
+\[tm] \e[tm] u2122 trade mark sign
+\[bs] \e[bs] --- Bell System logo +
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS "Currency symbols"
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[Do] $ u0024 dollar sign
+\[Do] \e[Do] u0024 dollar sign
+\[ct] \e[ct] u00A2 cent sign +
+\[eu] \e[eu] u20AC Euro sign
+\[Eu] \e[Eu] u20AC variant Euro sign
+\[Ye] \e[Ye] u00A5 yen sign
+\[Po] \e[Po] u00A3 pound sign
+\[Cs] \e[Cs] u00A4 currency sign
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS Units
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[de] \e[de] u00B0 degree sign +
+\[%0] \e[%0] u2030 per thousand, per mille sign
+\[fm] \e[fm] u2032 arc minute sign, foot mark +
+\[sd] \e[sd] u2033 arc second sign
+\[mc] \e[mc] u00B5 micro sign
+\[Of] \e[Of] u00AA feminine ordinal indicator
+\[Om] \e[Om] u00BA masculine ordinal indicator
+.TE
+.
+.
+.\" ====================================================================
+.SS "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 \[lq]bitwise or\[rq] sign:
+on typesetting devices,
+it is drawn shorter than the bar,
+about the same height as a capital letter.
+.
+Terminal devices unify
+.B \[rs][ba]
+and
+.BR \[rs][or] .
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[AN] \e[AN] u2227 logical and
+\[OR] \e[OR] u2228 logical or
+\[no] \e[no] u00AC logical not + ***
+\[tno] \e[tno] u00AC text variant of \f[B]\e[no]\f[]
+\[te] \e[te] u2203 there exists
+\[fa] \e[fa] u2200 for all
+\[st] \e[st] u220B such that
+\[3d] \e[3d] u2234 therefore
+\[tf] \e[tf] u2234 therefore
+| | u007C bar
+\[or] \e[or] u007C bitwise or +
+.TE
+.
+.
+.\" ====================================================================
+.SS "Mathematical symbols"
+.\" ====================================================================
+.
+.B \[rs][Fn]
+also appears in subsection \[lq]Supplementary Latin letters\[rq] above.
+.
+Observe the two varieties of the
+plus-minus,
+multiplication,
+and division signs;
+.BR \[rs][+\-] ,
+.BR \[rs][mu] ,
+and
+.B \[rs][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.
+.
+.
+.P
+In AT&T
+.IR troff ,
+.B \[rs](rn
+(\[lq]root en extender\[rq])
+served as the horizontal extension of the radical
+(square root)
+sign,
+.BR \[rs](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 \[lq]Rules and lines\[rq] above).
+.
+A contemporary font's radical sign might not ascend to such an extreme.
+.
+In
+.IR groff ,
+you can instead use
+.B \[rs][radicalex]
+to continue the radical sign
+.BR \[rs][sr] ;
+these special characters are intended for use with text fonts.
+.
+.B \[rs][sqrt]
+and
+.B \[rs][sqrtex]
+are their counterparts with mathematical spacing.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[12] \e[12] u00BD one half symbol +
+\[14] \e[14] u00BC one quarter symbol +
+\[34] \e[34] u00BE three quarters symbol +
+\[18] \e[18] u215B one eighth symbol
+\[38] \e[38] u215C three eighths symbol
+\[58] \e[58] u215D five eighths symbol
+\[78] \e[78] u215E seven eighths symbol
+\[S1] \e[S1] u00B9 superscript one
+\[S2] \e[S2] u00B2 superscript two
+\[S3] \e[S3] u00B3 superscript three
+
++ + u002B plus
+\[pl] \e[pl] u002B special variant of plus + ***
+\- \e[\-] u002D minus
+\[mi] \e[mi] u2212 special variant of minus + ***
+\[-+] \e[\-+] u2213 minus-plus
+\[+-] \e[+\-] u00B1 plus-minus + ***
+\[t+-] \e[t+\-] u00B1 text variant of \f[B]\e[+\-]\f[]
+\[md] \e[md] u22C5 multiplication dot
+\[mu] \e[mu] u00D7 multiplication sign + ***
+\[tmu] \e[tmu] u00D7 text variant of \f[B]\e[mu]\f[]
+\[c*] \e[c*] u2297 circled times
+\[c+] \e[c+] u2295 circled plus
+\[di] \e[di] u00F7 division sign + ***
+\[tdi] \e[tdi] u00F7 text variant of \f[B]\e[di]\f[]
+\[f/] \e[f/] u2044 fraction slash
+* * u002A asterisk
+\[**] \e[**] u2217 mathematical asterisk +
+
+\[<=] \e[<=] u2264 less than or equal to +
+\[>=] \e[>=] u2265 greater than or equal to +
+\[<<] \e[<<] u226A much less than
+\[>>] \e[>>] u226B much greater than
+\&= \&= u003D equals
+\[eq] \e[eq] u003D special variant of equals + ***
+\[!=] \e[!=] u003D_0338 not equals +
+\[==] \e[==] u2261 equivalent +
+\[ne] \e[ne] u2261_0338 not equivalent
+\[=~] \e[=\[ti]] u2245 approximately equal to
+\[|=] \e[|=] u2243 asymptotically equal to +
+\[ti] \e[ti] u007E tilde +
+\[ap] \e[ap] u223C similar to, tilde operator +
+\[~~] \e[\[ti]\[ti]] u2248 almost equal to
+\[~=] \e[\[ti]=] u2248 almost equal to
+\[pt] \e[pt] u221D proportional to +
+
+\[es] \e[es] u2205 empty set +
+\[mo] \e[mo] u2208 element of a set +
+\[nm] \e[nm] u2208_0338 not element of set
+\[sb] \e[sb] u2282 proper subset +
+\[nb] \e[nb] u2282_0338 not subset
+\[sp] \e[sp] u2283 proper superset +
+\[nc] \e[nc] u2283_0338 not superset
+\[ib] \e[ib] u2286 subset or equal +
+\[ip] \e[ip] u2287 superset or equal +
+\[ca] \e[ca] u2229 intersection, cap +
+\[cu] \e[cu] u222A union, cup +
+
+\[/_] \e[/_] u2220 angle
+\[pp] \e[pp] u22A5 perpendicular
+\[is] \e[is] u222B integral +
+\[integral] \e[integral] u222B integral ***
+\[sum] \e[sum] u2211 summation ***
+\[product] \e[product] u220F product ***
+\[coproduct] \e[coproduct] u2210 coproduct ***
+\[gr] \e[gr] u2207 gradient +
+\[sr] \e[sr] u221A radical sign, square root +
+\[rn] \e[rn] u203E overline +
+\[radicalex] \e[radicalex] --- radical extension
+\[sqrt] \e[sqrt] u221A radical sign, square root ***
+\[sqrtex] \e[sqrtex] --- radical extension ***
+
+\[lc] \e[lc] u2308 left ceiling +
+\[rc] \e[rc] u2309 right ceiling +
+\[lf] \e[lf] u230A left floor +
+\[rf] \e[rf] u230B right floor +
+
+\[if] \e[if] u221E infinity +
+\[Ah] \e[Ah] u2135 aleph symbol
+\[Fn] \e[Fn] u0192 lowercase f with hook, function
+\[Im] \e[Im] u2111 blackletter I, imaginary part
+\[Re] \e[Re] u211C blackletter R, real part
+\[wp] \e[wp] u2118 Weierstrass p
+\[pd] \e[pd] u2202 partial differential
+\[-h] \e[\-h] u210F h bar
+\[hbar] \e[hbar] u210F h bar
+.TE
+.
+.
+.\" ====================================================================
+.SS "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.
+.
+.
+.P
+.if t .ne 2v
+.if n .ne 3v \" account for horizontal rule
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[*A] \e[*A] u0391 uppercase alpha +
+\[*B] \e[*B] u0392 uppercase beta +
+\[*G] \e[*G] u0393 uppercase gamma +
+\[*D] \e[*D] u0394 uppercase delta +
+\[*E] \e[*E] u0395 uppercase epsilon +
+\[*Z] \e[*Z] u0396 uppercase zeta +
+\[*Y] \e[*Y] u0397 uppercase eta +
+\[*H] \e[*H] u0398 uppercase theta +
+\[*I] \e[*I] u0399 uppercase iota +
+\[*K] \e[*K] u039A uppercase kappa +
+\[*L] \e[*L] u039B uppercase lambda +
+\[*M] \e[*M] u039C uppercase mu +
+\[*N] \e[*N] u039D uppercase nu +
+\[*C] \e[*C] u039E uppercase xi +
+\[*O] \e[*O] u039F uppercase omicron +
+\[*P] \e[*P] u03A0 uppercase pi +
+\[*R] \e[*R] u03A1 uppercase rho +
+\[*S] \e[*S] u03A3 uppercase sigma +
+\[*T] \e[*T] u03A4 uppercase tau +
+\[*U] \e[*U] u03A5 uppercase upsilon +
+\[*F] \e[*F] u03A6 uppercase phi +
+\[*X] \e[*X] u03A7 uppercase chi +
+\[*Q] \e[*Q] u03A8 uppercase psi +
+\[*W] \e[*W] u03A9 uppercase omega +
+
+\[*a] \e[*a] u03B1 lowercase alpha +
+\[*b] \e[*b] u03B2 lowercase beta +
+\[*g] \e[*g] u03B3 lowercase gamma +
+\[*d] \e[*d] u03B4 lowercase delta +
+\[*e] \e[*e] u03B5 lowercase epsilon +
+\[*z] \e[*z] u03B6 lowercase zeta +
+\[*y] \e[*y] u03B7 lowercase eta +
+\[*h] \e[*h] u03B8 lowercase theta +
+\[*i] \e[*i] u03B9 lowercase iota +
+\[*k] \e[*k] u03BA lowercase kappa +
+\[*l] \e[*l] u03BB lowercase lambda +
+\[*m] \e[*m] u03BC lowercase mu +
+\[*n] \e[*n] u03BD lowercase nu +
+\[*c] \e[*c] u03BE lowercase xi +
+\[*o] \e[*o] u03BF lowercase omicron +
+\[*p] \e[*p] u03C0 lowercase pi +
+\[*r] \e[*r] u03C1 lowercase rho +
+\[*s] \e[*s] u03C3 lowercase sigma +
+\[*t] \e[*t] u03C4 lowercase tau +
+\[*u] \e[*u] u03C5 lowercase upsilon +
+\[*f] \e[*f] u03D5 lowercase phi +
+\[*x] \e[*x] u03C7 lowercase chi +
+\[*q] \e[*q] u03C8 lowercase psi +
+\[*w] \e[*w] u03C9 lowercase omega +
+
+\[+e] \e[+e] u03F5 variant epsilon (lunate)
+\[+h] \e[+h] u03D1 variant theta (cursive form)
+\[+p] \e[+p] u03D6 variant pi (similar to omega)
+\[+f] \e[+f] u03C6 variant phi (curly shape)
+\[ts] \e[ts] u03C2 terminal lowercase sigma +
+.TE
+.
+.
+.br
+.if t .ne 4v
+.if n .ne 5v \" account for horizontal rule
+.\" ====================================================================
+.SS "Playing card symbols"
+.\" ====================================================================
+.
+.TS
+L L L Lx.
+Output Input Unicode Notes
+_
+.T&
+L Lf(CR) L Lx.
+\[CL] \e[CL] u2663 solid club suit
+\[SP] \e[SP] u2660 solid spade suit
+\[HE] \e[HE] u2665 solid heart suit
+\[DI] \e[DI] u2666 solid diamond suit
+.TE
+.
+.
+.\" ====================================================================
+.SH History
+.\" ====================================================================
+.
+A consideration of the typefaces originally available to AT&T
+.I nroff \" AT&T
+and
+.I troff \" AT&T
+illuminates many conventions that one might regard as idiosyncratic
+fifty years afterward.
+.
+(See section \[lq]History\[rq] of
+.MR 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
+.RB ( \[dq] )
+served as a dieresis accent and neutral double quotation mark;
+decimal 39
+.RB ( \[aq] )
+as an acute accent,
+apostrophe,
+and closing (right) single quotation mark;
+decimal 45
+.RB ( \[-] )
+as a hyphen and a minus sign;
+decimal 94
+.RB ( \[ha] )
+as a circumflex accent and caret;
+decimal 96
+.RB ( \[ga] )
+as a grave accent and opening (left) single quotation mark;
+and decimal 126
+.RB ( \[ti] )
+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
+.IR kbd (VII)
+man page of the
+(First Edition)
+.I Unix Programmer's Manual.
+.
+.
+.br
+.ne 2v
+.P
+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 \[lq]special\[rq] font to ensure no loss of
+repertoire.
+.
+.
+.br
+.ne 2v
+.P
+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
+\[lq]de-unified\[rq] by the fonts provided;
+a decision whither to map an input \[lq]\-\[rq] therefore had to be
+taken.
+.
+.
+.br
+.if t .ne 5v
+.if t .ne 7v \" account for box border
+.P
+.TS
+center box;
+Lf(R).
+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] \[Fi] \[Fl]
+! $ % & ( ) \[oq] \[cq] * + \- . , / : ; = ? [ ] \[br]
+\[bu] \[sq] \[em] \[hy] \[ru] \[14] \[12] \[34] \
+\[de] \[dg] \[fm] \[ct] \[rg] \[co]
+.TE
+.
+.
+.P
+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 \[lq]to insulate the appearance of equations from the choice
+of standard [read: text] fonts\[rq]\[em]a priority since
+.I troff \" AT&T
+was turned to the task of mathematical typesetting as soon as it was
+developed.
+.
+.
+.P
+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.
+.
+.
+.br
+.if t .ne 5v
+.if t .ne 7v \" account for box border
+.P
+.TS
+center box;
+Lf(I),Lf(R).
+\[*a] \[*b] \[*g] \[*d] \[*e] \[*z] \[*y] \[*h] \[*i] \[*k] \[*l] \
+\[*m] \[*n] \[*c] \[*o] \[*p] \[*r] \[*s] \[ts] \[*t] \[*u] \[*f] \
+\[*x] \[*q] \[*w]
+\[*G] \[*D] \[*H] \[*L] \[*C] \[*P] \[*S] \[*U] \[*F] \[*Q] \[*W]
+\[dq] \[aa] \[rs] \[ha] \[ul] \[ga] \[ti] \[sl] < > { } # @ \
+\[pl] \[mi] \[eq] \[**]
+.\" We use \[radicalex] instead of \[rn] for more reliable simulation of
+.\" the typeface shown in Table I of CSTR #54 (1976); see subsection
+.\" "Mathematical symbols" above.
+\[>=] \[<=] \[==] \[~=] \[ap] \[!=] \
+\[ua] \[da] \[<-] \[->] \[mu] \[di] \[+-] \
+\[if] \[pd] \[gr] \[no] \[is] \[pt] \[sr] \[radicalex] \
+\[cu] \[ca] \[sb] \[sp] \[ib] \[ip] \[es] \[mo]
+\[sc] \[dd] \[lh] \[rh] \[or] \[ci] \
+\[lt] \[lb] \[rt] \[rb] \[lk] \[rk] \[bv] \[lf] \[rf] \[lc] \[rc]
+.TE
+.
+.
+.P
+One ASCII character as rendered by the Model 37 was apparently
+abandoned.
+.
+That device printed decimal 124 (\[or]) as a broken vertical line,
+like Unicode U+00A6 (\[bb]).
+.
+No equivalent was available on the C/A/T;
+the box rule
+.BR \[rs][br] ,
+brace vertical extension
+.\" CSTR #54 (1976 edition) called this the "bold vertical", probably
+.\" because it was thicker than the box rule and matched the thickness
+.\" of the bracket pieces \(lt, \(lb, \(rt, \(rb, \(lk, \(rk, and so on.
+.\" Saying "bold" could be misleading because it appeared only in the
+.\" special font, not a bold text font.
+.BR \[rs][bv] ,
+and \[lq]or\[rq] operator
+.B \[rs][or]
+were used as contextually appropriate.
+.
+.
+.P
+.\" In the Holt, Reinhart, Winston edition of the _Unix Programmer's
+.\" Manual_, Revised and Expanded Version, Volume 2 (1983), the square
+.\" \(sq in Times bold is _not_ shown as filled on page 226.
+.\"
+.\" ...but in the AT&T USG Unix 4.0 manual (ca. 1981), typeset on the
+.\" Autologic APS-5, the Times bold \(sq _is_ filled.
+.\"
+.\" https://www.tuhs.org/Archive/Documentation/Manuals/Unix_4.0/
+.\" Volume_1/00_Annotated_Table_of_Contents.pdf
+.\" Volume_1/C.1.2_NROFF_TROFF_Users_Manual.pdf
+.\" -- GBR
+Devices supported by AT&T device-independent
+.I troff
+exhibited some differences in glyph detail.
+.
+For example,
+on the Autologic APS-5 phototypesetter,
+the square
+.B \[rs](sq
+became filled in the Times bold face.
+.
+.
+.\" ====================================================================
+.SH Files
+.\" ====================================================================
+.
+The files below are loaded automatically by the default
+.IR troffrc .
+.
+.
+.TP
+.I /usr/\:\%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 \[lq]Accents\[rq] above.
+.
+.
+.TP
+.I /usr/\:\%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.
+.
+.
+.\" ====================================================================
+.SH Authors
+.\" ====================================================================
+.
+This document was written by
+.MT jjc@\:jclark\:.com
+James Clark
+.ME ,
+with additions by
+.MT wl@\:gnu\:.org
+Werner Lemberg
+.ME
+and
+.MT groff\-bernd\:.warken\-72@\:web\:.de
+Bernd Warken
+.ME ,
+revised to use
+.MR \%tbl 1
+by
+.MT esr@\:thyrsus\:.com
+Eric S.\& Raymond
+.ME ,
+and largely rewritten by
+.MT g.branden\:.robinson@\:gmail\:.com
+G.\& Branden Robinson
+.ME .
+.
+.
+.\" ====================================================================
+.SH "See also"
+.\" ====================================================================
+.
+.IR "Groff: The GNU Implementation of troff" ,
+by Trent A.\& Fisher and Werner Lemberg,
+is the primary
+.I groff
+manual.
+.
+Section \[lq]Using Symbols\[rq] may be of particular note.
+.
+You can browse it interactively with \[lq]info \[aq](groff) Using
+Symbols\[aq]\[rq].
+.
+.
+.P
+\[lq]An extension to the
+.I troff
+character set for Europe\[rq],
+E.G.\& Keizer,
+K.J.\& Simonsen,
+J.\& Akkerhuis;
+EUUG Newsletter,
+Volume 9,
+No.\& 2,
+Summer 1989
+.
+.
+.P
+.UR http://\:www\:.unicode\:.org
+The Unicode Standard
+.UE
+.
+.
+.br
+.ne 2v
+.P
+.UR https://\:www\:.aivosto\:.com/\:articles/\:charsets\-7bit\:.html
+\[lq]7-bit Character Sets\[rq]
+.UE
+by Tuomas Salste documents the inherent ambiguity and configurable code
+points of the ASCII encoding standard.
+.
+.
+.P
+\[lq]Nroff/Troff User's Manual\[rq]
+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 \[lq]typesetter
+.IR roff \[rq]
+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
+.I troff \" AT&T
+users.
+.
+.
+.P
+.MR groff_rfc1345 7
+describes an alternative set of special character glyph names,
+which extends and in some cases overrides the definitions listed above.
+.
+.
+.P
+.MR groff 1 ,
+.MR troff 1 ,
+.MR groff 7
+.
+.
+.\" Restore compatibility mode (for, e.g., Solaris 10/11).
+.cp \n[*groff_groff_char_7_man_C]
+.do rr *groff_groff_char_7_man_C
+.
+.
+.\" Local Variables:
+.\" fill-column: 72
+.\" mode: nroff
+.\" tab-width: 20
+.\" End:
+.\" vim: set filetype=groff tabstop=20 textwidth=72: