Hi Doug, At 2023-04-01T19:45:19-0400, Douglas McIlroy wrote: > I went to see what this proposal meant and ran into undefined jargon > in groff_char.7.
This, and phrases like "in the actual version", are regrettable defects in the groff 1.22.4 version of this man page. The one in the groff 1.23.0.rc2 and .rc3 release candidates does not have them. This page is one that I've heavily revised. I'm attaching a copy for your consideration. I'd particularly welcome your comments on the new "History" section. > Yes, info groff probably tells me more than I want to know. Still, I > expect the man page to be terse, but intelligible. Fair. I hope the intelligibility of the present form is improved. > What's an "entity"? Suggestive of conceptual fuzziness on the part of the writer, I would propose. But I can't blame them; the difficulty of comprehending groff's flexible and complex character to glyph transformation process is the main reason I have not yet revised that part of our Texinfo manual. > Fortunately, Dave Kemper's post shed light on this question. > > The first use of .char that came to mind was > .char \[ntilde] \o'n~' > which would collide badly with the following ancient trick for > unbreakable, unpaddable space. (Ignore the question of whether the > tilde at hand is usable as a diacritical.) > .tr ~ > a~b~c You may be one of a dwindling number of people for whom that ancient trick comes to mind. :) But we do continue to support it, and I see no reason to withdraw it. > This, I guess, is typical of the motivation for the change. I was spurred into this by noticing a problem last July with what I think was a historical troff document. I can't lay my hands it now, but the following short example suggests the issue. $ cat EXPERIMENTS/tr-in-env.roff .nf .tr ab bab .ev 1 bab .br .ev bab .pl \n(nlu This produces 3 lines of "bbb". The problem I observed, as best I can recall, was that a document temporarily used `tr` to make input more convenient. The trouble was, the same character they were translating turned up in one of their page headers or footers. So, depending on how the document got modified and the resulting placement of the `tr`-ed material, the headers/footers might get corrupted or might not. A lengthier, but contrived, example of this is at <https://savannah.gnu.org/bugs/?62691>. I suppose there are workarounds one could coach the user to undertake in such a situation, but once I got to thinking about it, it struck me that there should be a cleaner division of responsibility between `tr` and `char`. My suggestion is twofold: (1) that `tr` should be used for permuting what we can term groff's internal character set; meaning the 94 printable characters of ASCII/Basic Latin, and whatever special characters happen to be defined; and (2) `char` and `rchar` are for adding and removing members of the set of special characters. (You can try to `rchar` an ordinary Basic Latin character; it will silently fail. I mean to make that no longer silent.[1]) It is necessary to consider the impact of these processes on diversions. I don't presently think my proposal is disruptive to the status quo in that respect. When a diversion is populated, special character definitions are already resolved, and just as with string interpolations, using the `unformat` request does not recover their original forms. Illustration (with groff 1.22.4): $ cat EXPERIMENTS/char-in-a-diversion.groff .nf .char \[zz] FNORD .di XX You didn't \[zz] this. .di Hello, world. diverted XX: \c .XX .unformat XX unformatted XX: \*[XX] .pl \n[nl]u $ nroff -Tascii EXPERIMENTS/char-in-a-diversion.groff Hello, world. diverted XX: You didn't FNORD this. unformatted XX: You didn't FNORD this. $ > Suppose the change isn't made? What does .char do for you that .ds > doesn't? Certainly nothing essential in the example above. However, it > can avoid the ugliness of string invocations. I don't remember where I saw this trick, but you can use a `char`-defined object as a margin character, and I suppose just about anywhere else the language syntax is accepting of an atomic character. The utility of this comes in when realizing that someone might reasonably want to set a margin character in a particular typeface (maybe it's a dingbat--most of these don't have special character names) and/or in a certain color. Recasting the language of the 1.22.4 Texinfo manual, `char` is described as doing this to the RHS of its definition: "[the RHS] is processed in a temporary environment and the result is wrapped up into a single object. Compatibility mode is turned off and the escape character is set to '\' while [it] is being processed. Any emboldening, constant spacing or track kerning is applied to this object rather than to individual characters in [it]." > I regard the potential benefit mentioned in the last sentence as > unpersuasive, but the potential catastrophe of the initial example as > tilting the scales toward the proposal. I think it would help distinguish and orthogonalize the language if `char` character definitions remained global to formatter state, and translations/transliterations with `tr` became properties of the environment. I suppose roff veterans are used to it, but my mind twists even when looking at my own example in Savannah #62691 (linked above). Namely, .tr @--@ is not a no-op! In fact, it works a lot like file descriptor redirections in the shell. foo >/dev/null 2>&1 | grep error Each left-hand member of a `tr` translation pair identifies a place in the translation "from" space, and each right-hand member a place in the "to" space. The transform is then done atomically. On occasions when I want to send throw standard output away but grep the standard error stream, I haltingly think through this same issue. Regards, Branden [1] https://savannah.gnu.org/bugs/?63985
'\" t .TH groff_char 7 "20 March 2023" "groff 1.23.0.rc3.111-78afd" .SH Name groff_char \- GNU .I roff special character and glyph repertoire . . .\" ==================================================================== .\" Legal Terms .\" ==================================================================== .\" .\" Copyright (C) 1989-2022 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. . However, its input character set is restricted to that defined by the standards ISO Latin-1 (ISO 8859-1) and IBM code page 1047 (an EBCDIC arrangement of Latin-1). . For ease of document maintenance in UTF-8 environments, it is advisable to use only the Unicode basic Latin code points, a subset of all of the foregoing historically referred to as \%US-ASCII, .\" 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. . . .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. . Its 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. . (Characters that don't require an escape sequence for their expression, like \[lq]a\[rq], are termed \[lq]ordinary\[rq].) . . .P As in other respects, .I groff has removed historical .I roff limitations on the lengths of special character escape sequences, 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. . . .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 ninety-four 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 seven of the ninety-four code points in this range 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 characters in the Latin-1 supplement 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. . . .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. . Any character valid in a .I groff identifier may be used in a glyph name. . 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-glyph 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 with the .B char request, enabling the user to devise .I ad hoc names for them; 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. . With this form, any Unicode character can be accessed by code point using 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-glyph\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 .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. \[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 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"] 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 typestter 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 /home/\:\%branden/\:\%groff/\:\%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 /home/\:\%branden/\:\%groff/\:\%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:
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