.\" $Id$
.\"
.\" Copyright (c) 2003 Jason McIntyre <jmc@openbsd.org>
.\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
.\" Copyright (c) 2011 Ingo Schwarze <schwarze@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate$
.Dt MANDOC_CHAR 7
.Os
.Sh NAME
.Nm mandoc_char
.Nd mandoc special characters
.Sh DESCRIPTION
This page documents the
.Xr roff 7
escape sequences accepted by
.Xr mandoc 1
to represent special characters in
.Xr mdoc 7
and
.Xr man 7
documents.
.Pp
The rendering depends on the
.Xr mandoc 1
output mode; in ASCII output, most characters are completely
unintelligible.
For that reason, using any of the special characters documented here,
except those discussed in the
.Sx DESCRIPTION ,
is strongly discouraged; they are supported merely for backwards
compatibility with existing documents.
.Pp
In particular, in English manual pages, do not use special-character
escape sequences to represent national language characters in author
names; instead, provide ASCII transcriptions of the names.
.Ss Dashes and Hyphens
In typography there are different types of dashes of various width:
the hyphen (-),
the minus sign (\-),
the en-dash (\(en),
and the em-dash (\(em).
.Pp
Hyphens are used for adjectives;
to separate the two parts of a compound word;
or to separate a word across two successive lines of text.
The hyphen does not need to be escaped:
.Bd -unfilled -offset indent
blue-eyed
lorry-driver
.Ed
.Pp
The mathematical minus sign is used for negative numbers or subtraction.
It should be written as
.Sq \e- :
.Bd -unfilled -offset indent
a = 3 \e- 1;
b = \e-2;
.Ed
.Pp
The en-dash is used to separate the two elements of a range,
or can be used the same way as an em-dash.
It should be written as
.Sq \e(en :
.Bd -unfilled -offset indent
pp. 95\e(en97.
Go away \e(en or else!
.Ed
.Pp
The em-dash can be used to show an interruption
or can be used the same way as colons, semi-colons, or parentheses.
It should be written as
.Sq \e(em :
.Bd -unfilled -offset indent
Three things \e(em apples, oranges, and bananas.
This is not that \e(em rather, this is that.
.Ed
.Pp
Note:
hyphens, minus signs, and en-dashes look identical under normal ASCII output.
Other formats, such as PostScript, render them correctly,
with differing widths.
.Ss Spaces
To separate words in normal text, for indenting and alignment
in literal context, and when none of the following special cases apply,
just use the normal space character
.Pq Sq \ .
.Pp
When filling text, output lines may be broken between words, i.e. at space
characters.
To prevent a line break between two particular words,
use the unpaddable non-breaking space escape sequence
.Pq Sq \e\ \&
instead of the normal space character.
For example, the input string
.Dq number\e\ 1
will be kept together as
.Dq number\ 1
on the same output line.
.Pp
On request and macro lines, the normal space character serves as an
argument delimiter.
To include whitespace into arguments, quoting is usually the best choice;
see the MACRO SYNTAX section in
.Xr roff 7 .
In some cases, using the non-breaking space escape sequence
.Pq Sq \e\ \&
may be preferable.
.Pp
To escape macro names and to protect whitespace at the end
of input lines, the zero-width space
.Pq Sq \e&
is often useful.
For example, in
.Xr mdoc 7 ,
a normal space character can be displayed in single quotes in either
of the following ways:
.Pp
.Dl .Sq \(dq \(dq
.Dl .Sq \e \e&
.Ss Quotes
On request and macro lines, the double-quote character
.Pq Sq \(dq
is handled specially to allow quoting.
One way to prevent this special handling is by using the
.Sq \e(dq
escape sequence.
.Pp
Note that on text lines, literal double-quote characters can be used
verbatim.
All other quote-like characters can be used verbatim as well,
even on request and macro lines.
.Ss Periods
The period
.Pq Sq \&.
is handled specially at the beginning of an input line,
where it introduces a
.Xr roff 7
request or a macro, and when appearing alone as a macro argument in
.Xr mdoc 7 .
In such situations, prepend a zero-width space
.Pq Sq \e&.
to make it behave like normal text.
.Pp
Do not use the
.Sq \e.
escape sequence.
It does not prevent special handling of the period.
.Ss Backslashes
To include a literal backslash
.Pq Sq \e
into the output, use the
.Pq Sq \ee
escape sequence.
.Pp
Note that doubling it
.Pq Sq \e\e
is not the right way to output a backslash.
Because
.Xr mandoc 1
does not implement full
.Xr roff 7
functionality, it may work with
.Xr mandoc 1 ,
but it may have weird effects on complete
.Xr roff 7
implementations.
.Sh SPECIAL CHARACTERS
Special characters are encoded as
.Sq \eX
.Pq for a one-character escape ,
.Sq \e(XX
.Pq two-character ,
and
.Sq \e[N]
.Pq N-character .
For details, see the
.Em Special Characters
subsection of the
.Xr roff 7
manual.
.Pp
Spacing:
.Bl -column "Input" "Description" -offset indent -compact
.It Em Input Ta Em Description
.It Sq \e\ \& Ta unpaddable non-breaking space
.It \e~ Ta paddable non-breaking space
.It \e0 Ta unpaddable, breaking digit-width space
.It \e| Ta one-sixth \e(em narrow space, zero width in nroff mode
.It \e^ Ta one-twelfth \e(em half-narrow space, zero width in nroff
.It \e& Ta zero-width space
.It \e% Ta zero-width space allowing hyphenation
.El
.Pp
Lines:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(ba Ta \(ba Ta bar
.It \e(br Ta \(br Ta box rule
.It \e(ul Ta \(ul Ta underscore
.It \e(rn Ta \(rn Ta overline
.It \e(bb Ta \(bb Ta broken bar
.It \e(sl Ta \(sl Ta forward slash
.It \e(rs Ta \(rs Ta backward slash
.El
.Pp
Text markers:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(ci Ta \(ci Ta circle
.It \e(bu Ta \(bu Ta bullet
.It \e(dd Ta \(dd Ta double dagger
.It \e(dg Ta \(dg Ta dagger
.It \e(lz Ta \(lz Ta lozenge
.It \e(sq Ta \(sq Ta white square
.It \e(ps Ta \(ps Ta paragraph
.It \e(sc Ta \(sc Ta section
.It \e(lh Ta \(lh Ta left hand
.It \e(rh Ta \(rh Ta right hand
.It \e(at Ta \(at Ta at
.It \e(sh Ta \(sh Ta hash (pound)
.It \e(CR Ta \(CR Ta carriage return
.It \e(OK Ta \(OK Ta check mark
.El
.Pp
Legal symbols:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(co Ta \(co Ta copyright
.It \e(rg Ta \(rg Ta registered
.It \e(tm Ta \(tm Ta trademarked
.El
.Pp
Punctuation:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(em Ta \(em Ta em-dash
.It \e(en Ta \(en Ta en-dash
.It \e(hy Ta \(hy Ta hyphen
.It \ee Ta \e Ta back-slash
.It \e. Ta \. Ta period
.It \e(r! Ta \(r! Ta upside-down exclamation
.It \e(r? Ta \(r? Ta upside-down question
.El
.Pp
Quotes:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(Bq Ta \(Bq Ta right low double-quote
.It \e(bq Ta \(bq Ta right low single-quote
.It \e(lq Ta \(lq Ta left double-quote
.It \e(rq Ta \(rq Ta right double-quote
.It \e(oq Ta \(oq Ta left single-quote
.It \e(cq Ta \(cq Ta right single-quote
.It \e(aq Ta \(aq Ta apostrophe quote (text)
.It \e(dq Ta \(dq Ta double quote (text)
.It \e(Fo Ta \(Fo Ta left guillemet
.It \e(Fc Ta \(Fc Ta right guillemet
.It \e(fo Ta \(fo Ta left single guillemet
.It \e(fc Ta \(fc Ta right single guillemet
.El
.Pp
Brackets:
.Bl -column "xxbracketrightbtx" Rendered Description -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(lB Ta \(lB Ta left bracket
.It \e(rB Ta \(rB Ta right bracket
.It \e(lC Ta \(lC Ta left brace
.It \e(rC Ta \(rC Ta right brace
.It \e(la Ta \(la Ta left angle
.It \e(ra Ta \(ra Ta right angle
.It \e(bv Ta \(bv Ta brace extension
.It \e[braceex] Ta \[braceex] Ta brace extension
.It \e[bracketlefttp] Ta \[bracketlefttp] Ta top-left hooked bracket
.It \e[bracketleftbt] Ta \[bracketleftbt] Ta bottom-left hooked bracket
.It \e[bracketleftex] Ta \[bracketleftex] Ta left hooked bracket extension
.It \e[bracketrighttp] Ta \[bracketrighttp] Ta top-right hooked bracket
.It \e[bracketrightbt] Ta \[bracketrightbt] Ta bottom-right hooked bracket
.It \e[bracketrightex] Ta \[bracketrightex] Ta right hooked bracket extension
.It \e(lt Ta \(lt Ta top-left hooked brace
.It \e[bracelefttp] Ta \[bracelefttp] Ta top-left hooked brace
.It \e(lk Ta \(lk Ta mid-left hooked brace
.It \e[braceleftmid] Ta \[braceleftmid] Ta mid-left hooked brace
.It \e(lb Ta \(lb Ta bottom-left hooked brace
.It \e[braceleftbt] Ta \[braceleftbt] Ta bottom-left hooked brace
.It \e[braceleftex] Ta \[braceleftex] Ta left hooked brace extension
.It \e(rt Ta \(rt Ta top-left hooked brace
.It \e[bracerighttp] Ta \[bracerighttp] Ta top-right hooked brace
.It \e(rk Ta \(rk Ta mid-right hooked brace
.It \e[bracerightmid] Ta \[bracerightmid] Ta mid-right hooked brace
.It \e(rb Ta \(rb Ta bottom-right hooked brace
.It \e[bracerightbt] Ta \[bracerightbt] Ta bottom-right hooked brace
.It \e[bracerightex] Ta \[bracerightex] Ta right hooked brace extension
.It \e[parenlefttp] Ta \[parenlefttp] Ta top-left hooked parenthesis
.It \e[parenleftbt] Ta \[parenleftbt] Ta bottom-left hooked parenthesis
.It \e[parenleftex] Ta \[parenleftex] Ta left hooked parenthesis extension
.It \e[parenrighttp] Ta \[parenrighttp] Ta top-right hooked parenthesis
.It \e[parenrightbt] Ta \[parenrightbt] Ta bottom-right hooked parenthesis
.It \e[parenrightex] Ta \[parenrightex] Ta right hooked parenthesis extension
.El
.Pp
Arrows:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(<- Ta \(<- Ta left arrow
.It \e(-> Ta \(-> Ta right arrow
.It \e(<> Ta \(<> Ta left-right arrow
.It \e(da Ta \(da Ta down arrow
.It \e(ua Ta \(ua Ta up arrow
.It \e(va Ta \(va Ta up-down arrow
.It \e(lA Ta \(lA Ta left double-arrow
.It \e(rA Ta \(rA Ta right double-arrow
.It \e(hA Ta \(hA Ta left-right double-arrow
.It \e(uA Ta \(uA Ta up double-arrow
.It \e(dA Ta \(dA Ta down double-arrow
.It \e(vA Ta \(vA Ta up-down double-arrow
.El
.Pp
Logical:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(AN Ta \(AN Ta logical and
.It \e(OR Ta \(OR Ta logical or
.It \e(no Ta \(no Ta logical not
.It \e[tno] Ta \[tno] Ta logical not (text)
.It \e(te Ta \(te Ta existential quantifier
.It \e(fa Ta \(fa Ta universal quantifier
.It \e(st Ta \(st Ta such that
.It \e(tf Ta \(tf Ta therefore
.It \e(3d Ta \(3d Ta therefore
.It \e(or Ta \(or Ta bitwise or
.El
.Pp
Mathematical:
.Bl -column "xxcoproductxx" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(pl Ta \(pl Ta plus
.It \e(mi Ta \(mi Ta minus
.It \e- Ta \- Ta minus (text)
.It \e(-+ Ta \(-+ Ta minus-plus
.It \e(+- Ta \(+- Ta plus-minus
.It \e[t+-] Ta \[t+-] Ta plus-minus (text)
.It \e(pc Ta \(pc Ta center-dot
.It \e(mu Ta \(mu Ta multiply
.It \e[tmu] Ta \[tmu] Ta multiply (text)
.It \e(c* Ta \(c* Ta circle-multiply
.It \e(c+ Ta \(c+ Ta circle-plus
.It \e(di Ta \(di Ta divide
.It \e[tdi] Ta \[tdi] Ta divide (text)
.It \e(f/ Ta \(f/ Ta fraction
.It \e(** Ta \(** Ta asterisk
.It \e(<= Ta \(<= Ta less-than-equal
.It \e(>= Ta \(>= Ta greater-than-equal
.It \e(<< Ta \(<< Ta much less
.It \e(>> Ta \(>> Ta much greater
.It \e(eq Ta \(eq Ta equal
.It \e(!= Ta \(!= Ta not equal
.It \e(== Ta \(== Ta equivalent
.It \e(ne Ta \(ne Ta not equivalent
.It \e(ap Ta \(ap Ta tilde operator
.It \e(|= Ta \(|= Ta asymptotically equal
.It \e(=~ Ta \(=~ Ta approximately equal
.It \e(~~ Ta \(~~ Ta almost equal
.It \e(~= Ta \(~= Ta almost equal
.It \e(pt Ta \(pt Ta proportionate
.It \e(es Ta \(es Ta empty set
.It \e(mo Ta \(mo Ta element
.It \e(nm Ta \(nm Ta not element
.It \e(sb Ta \(sb Ta proper subset
.It \e(nb Ta \(nb Ta not subset
.It \e(sp Ta \(sp Ta proper superset
.It \e(nc Ta \(nc Ta not superset
.It \e(ib Ta \(ib Ta reflexive subset
.It \e(ip Ta \(ip Ta reflexive superset
.It \e(ca Ta \(ca Ta intersection
.It \e(cu Ta \(cu Ta union
.It \e(/_ Ta \(/_ Ta angle
.It \e(pp Ta \(pp Ta perpendicular
.It \e(is Ta \(is Ta integral
.It \e[integral] Ta \[integral] Ta integral
.It \e[sum] Ta \[sum] Ta summation
.It \e[product] Ta \[product] Ta product
.It \e[coproduct] Ta \[coproduct] Ta coproduct
.It \e(gr Ta \(gr Ta gradient
.It \e(sr Ta \(sr Ta square root
.It \e[sqrt] Ta \[sqrt] Ta square root
.It \e(lc Ta \(lc Ta left-ceiling
.It \e(rc Ta \(rc Ta right-ceiling
.It \e(lf Ta \(lf Ta left-floor
.It \e(rf Ta \(rf Ta right-floor
.It \e(if Ta \(if Ta infinity
.It \e(Ah Ta \(Ah Ta aleph
.It \e(Im Ta \(Im Ta imaginary
.It \e(Re Ta \(Re Ta real
.It \e(pd Ta \(pd Ta partial differential
.It \e(-h Ta \(-h Ta Planck constant over 2\(*p
.It \e[12] Ta \[12] Ta one-half
.It \e[14] Ta \[14] Ta one-fourth
.It \e[34] Ta \[34] Ta three-fourths
.El
.Pp
Ligatures:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(ff Ta \(ff Ta ff ligature
.It \e(fi Ta \(fi Ta fi ligature
.It \e(fl Ta \(fl Ta fl ligature
.It \e(Fi Ta \(Fi Ta ffi ligature
.It \e(Fl Ta \(Fl Ta ffl ligature
.It \e(AE Ta \(AE Ta AE
.It \e(ae Ta \(ae Ta ae
.It \e(OE Ta \(OE Ta OE
.It \e(oe Ta \(oe Ta oe
.It \e(ss Ta \(ss Ta German eszett
.It \e(IJ Ta \(IJ Ta IJ ligature
.It \e(ij Ta \(ij Ta ij ligature
.El
.Pp
Accents:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(a" Ta \(a" Ta Hungarian umlaut
.It \e(a- Ta \(a- Ta macron
.It \e(a. Ta \(a. Ta dotted
.It \e(a^ Ta \(a^ Ta circumflex
.It \e(aa Ta \(aa Ta acute
.It \e' Ta \' Ta acute
.It \e(ga Ta \(ga Ta grave
.It \e` Ta \` Ta grave
.It \e(ab Ta \(ab Ta breve
.It \e(ac Ta \(ac Ta cedilla
.It \e(ad Ta \(ad Ta dieresis
.It \e(ah Ta \(ah Ta caron
.It \e(ao Ta \(ao Ta ring
.It \e(a~ Ta \(a~ Ta tilde
.It \e(ho Ta \(ho Ta ogonek
.It \e(ha Ta \(ha Ta hat (text)
.It \e(ti Ta \(ti Ta tilde (text)
.El
.Pp
Accented letters:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e('A Ta \('A Ta acute A
.It \e('E Ta \('E Ta acute E
.It \e('I Ta \('I Ta acute I
.It \e('O Ta \('O Ta acute O
.It \e('U Ta \('U Ta acute U
.It \e('a Ta \('a Ta acute a
.It \e('e Ta \('e Ta acute e
.It \e('i Ta \('i Ta acute i
.It \e('o Ta \('o Ta acute o
.It \e('u Ta \('u Ta acute u
.It \e(`A Ta \(`A Ta grave A
.It \e(`E Ta \(`E Ta grave E
.It \e(`I Ta \(`I Ta grave I
.It \e(`O Ta \(`O Ta grave O
.It \e(`U Ta \(`U Ta grave U
.It \e(`a Ta \(`a Ta grave a
.It \e(`e Ta \(`e Ta grave e
.It \e(`i Ta \(`i Ta grave i
.It \e(`o Ta \(`i Ta grave o
.It \e(`u Ta \(`u Ta grave u
.It \e(~A Ta \(~A Ta tilde A
.It \e(~N Ta \(~N Ta tilde N
.It \e(~O Ta \(~O Ta tilde O
.It \e(~a Ta \(~a Ta tilde a
.It \e(~n Ta \(~n Ta tilde n
.It \e(~o Ta \(~o Ta tilde o
.It \e(:A Ta \(:A Ta dieresis A
.It \e(:E Ta \(:E Ta dieresis E
.It \e(:I Ta \(:I Ta dieresis I
.It \e(:O Ta \(:O Ta dieresis O
.It \e(:U Ta \(:U Ta dieresis U
.It \e(:a Ta \(:a Ta dieresis a
.It \e(:e Ta \(:e Ta dieresis e
.It \e(:i Ta \(:i Ta dieresis i
.It \e(:o Ta \(:o Ta dieresis o
.It \e(:u Ta \(:u Ta dieresis u
.It \e(:y Ta \(:y Ta dieresis y
.It \e(^A Ta \(^A Ta circumflex A
.It \e(^E Ta \(^E Ta circumflex E
.It \e(^I Ta \(^I Ta circumflex I
.It \e(^O Ta \(^O Ta circumflex O
.It \e(^U Ta \(^U Ta circumflex U
.It \e(^a Ta \(^a Ta circumflex a
.It \e(^e Ta \(^e Ta circumflex e
.It \e(^i Ta \(^i Ta circumflex i
.It \e(^o Ta \(^o Ta circumflex o
.It \e(^u Ta \(^u Ta circumflex u
.It \e(,C Ta \(,C Ta cedilla C
.It \e(,c Ta \(,c Ta cedilla c
.It \e(/L Ta \(/L Ta stroke L
.It \e(/l Ta \(/l Ta stroke l
.It \e(/O Ta \(/O Ta stroke O
.It \e(/o Ta \(/o Ta stroke o
.It \e(oA Ta \(oA Ta ring A
.It \e(oa Ta \(oa Ta ring a
.El
.Pp
Special letters:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(-D Ta \(-D Ta Eth
.It \e(Sd Ta \(Sd Ta eth
.It \e(TP Ta \(TP Ta Thorn
.It \e(Tp Ta \(Tp Ta thorn
.It \e(.i Ta \(.i Ta dotless i
.It \e(.j Ta \(.j Ta dotless j
.El
.Pp
Currency:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(Do Ta \(Do Ta dollar
.It \e(ct Ta \(ct Ta cent
.It \e(Eu Ta \(Eu Ta Euro symbol
.It \e(eu Ta \(eu Ta Euro symbol
.It \e(Ye Ta \(Ye Ta yen
.It \e(Po Ta \(Po Ta pound
.It \e(Cs Ta \(Cs Ta Scandinavian
.It \e(Fn Ta \(Fn Ta florin
.El
.Pp
Units:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(de Ta \(de Ta degree
.It \e(%0 Ta \(%0 Ta per-thousand
.It \e(fm Ta \(fm Ta minute
.It \e(sd Ta \(sd Ta second
.It \e(mc Ta \(mc Ta micro
.El
.Pp
Greek letters:
.Bl -column "Input" "Rendered" "Description" -offset indent -compact
.It Em Input Ta Em Rendered Ta Em Description
.It \e(*A Ta \(*A Ta Alpha
.It \e(*B Ta \(*B Ta Beta
.It \e(*G Ta \(*G Ta Gamma
.It \e(*D Ta \(*D Ta Delta
.It \e(*E Ta \(*E Ta Epsilon
.It \e(*Z Ta \(*Z Ta Zeta
.It \e(*Y Ta \(*Y Ta Eta
.It \e(*H Ta \(*H Ta Theta
.It \e(*I Ta \(*I Ta Iota
.It \e(*K Ta \(*K Ta Kappa
.It \e(*L Ta \(*L Ta Lambda
.It \e(*M Ta \(*M Ta Mu
.It \e(*N Ta \(*N Ta Nu
.It \e(*C Ta \(*C Ta Xi
.It \e(*O Ta \(*O Ta Omicron
.It \e(*P Ta \(*P Ta Pi
.It \e(*R Ta \(*R Ta Rho
.It \e(*S Ta \(*S Ta Sigma
.It \e(*T Ta \(*T Ta Tau
.It \e(*U Ta \(*U Ta Upsilon
.It \e(*F Ta \(*F Ta Phi
.It \e(*X Ta \(*X Ta Chi
.It \e(*Q Ta \(*Q Ta Psi
.It \e(*W Ta \(*W Ta Omega
.It \e(*a Ta \(*a Ta alpha
.It \e(*b Ta \(*b Ta beta
.It \e(*g Ta \(*g Ta gamma
.It \e(*d Ta \(*d Ta delta
.It \e(*e Ta \(*e Ta epsilon
.It \e(*z Ta \(*z Ta zeta
.It \e(*y Ta \(*y Ta eta
.It \e(*h Ta \(*h Ta theta
.It \e(*i Ta \(*i Ta iota
.It \e(*k Ta \(*k Ta kappa
.It \e(*l Ta \(*l Ta lambda
.It \e(*m Ta \(*m Ta mu
.It \e(*n Ta \(*n Ta nu
.It \e(*c Ta \(*c Ta xi
.It \e(*o Ta \(*o Ta omicron
.It \e(*p Ta \(*p Ta pi
.It \e(*r Ta \(*r Ta rho
.It \e(*s Ta \(*s Ta sigma
.It \e(*t Ta \(*t Ta tau
.It \e(*u Ta \(*u Ta upsilon
.It \e(*f Ta \(*f Ta phi
.It \e(*x Ta \(*x Ta chi
.It \e(*q Ta \(*q Ta psi
.It \e(*w Ta \(*w Ta omega
.It \e(+h Ta \(+h Ta theta variant
.It \e(+f Ta \(+f Ta phi variant
.It \e(+p Ta \(+p Ta pi variant
.It \e(+e Ta \(+e Ta epsilon variant
.It \e(ts Ta \(ts Ta sigma terminal
.El
.Sh PREDEFINED STRINGS
Predefined strings are inherited from the macro packages of historical
troff implementations.
They are
.Em not recommended
for use, as they differ across implementations.
Manuals using these predefined strings are almost certainly not
portable.
.Pp
Their syntax is similar to special characters, using
.Sq \e*X
.Pq for a one-character escape ,
.Sq \e*(XX
.Pq two-character ,
and
.Sq \e*[N]
.Pq N-character .
For details, see the
.Em Predefined Strings
subsection of the
.Xr roff 7
manual.
.Bl -column "Input" "Rendered" "Description" -offset indent
.It Em Input Ta Em Rendered Ta Em Description
.It \e*(Ba Ta \*(Ba Ta vertical bar
.It \e*(Ne Ta \*(Ne Ta not equal
.It \e*(Ge Ta \*(Ge Ta greater-than-equal
.It \e*(Le Ta \*(Le Ta less-than-equal
.It \e*(Gt Ta \*(Gt Ta greater-than
.It \e*(Lt Ta \*(Lt Ta less-than
.It \e*(Pm Ta \*(Pm Ta plus-minus
.It \e*(If Ta \*(If Ta infinity
.It \e*(Pi Ta \*(Pi Ta pi
.It \e*(Na Ta \*(Na Ta NaN
.It \e*(Am Ta \*(Am Ta ampersand
.It \e*R Ta \*R Ta restricted mark
.It \e*(Tm Ta \*(Tm Ta trade mark
.It \e*q Ta \*q Ta double-quote
.It \e*(Rq Ta \*(Rq Ta right-double-quote
.It \e*(Lq Ta \*(Lq Ta left-double-quote
.It \e*(lp Ta \*(lp Ta right-parenthesis
.It \e*(rp Ta \*(rp Ta left-parenthesis
.It \e*(lq Ta \*(lq Ta left double-quote
.It \e*(rq Ta \*(rq Ta right double-quote
.It \e*(ua Ta \*(ua Ta up arrow
.It \e*(va Ta \*(va Ta up-down arrow
.It \e*(<= Ta \*(<= Ta less-than-equal
.It \e*(>= Ta \*(>= Ta greater-than-equal
.It \e*(aa Ta \*(aa Ta acute
.It \e*(ga Ta \*(ga Ta grave
.It \e*(Px Ta \*(Px Ta POSIX standard name
.It \e*(Ai Ta \*(Ai Ta ANSI standard name
.El
.Sh UNICODE CHARACTERS
The escape sequences
.Pp
.Dl \e[uXXXX] and \eC'uXXXX'
.Pp
are interpreted as Unicode codepoints.
The codepoint must be in the range above U+0080 and less than U+10FFFF.
For compatibility, the hexadecimal digits
.Sq A
to
.Sq F
must be given as uppercase characters,
and points must be zero-padded to four characters; if
greater than four characters, no zero padding is allowed.
Unicode surrogates are not allowed.
.\" .Pp
.\" Unicode glyphs attenuate to the
.\" .Sq \&?
.\" character if invalid or not rendered by current output media.
.Sh NUMBERED CHARACTERS
For backward compatibility with existing manuals,
.Xr mandoc 1
also supports the
.Pp
.Dl \eN\(aq Ns Ar number Ns \(aq
.Pp
escape sequence, inserting the character
.Ar number
from the current character set into the output.
Of course, this is inherently non-portable and is already marked
as deprecated in the Heirloom roff manual.
For example, do not use \eN'34', use \e(dq, or even the plain
.Sq \(dq
character where possible.
.Sh COMPATIBILITY
This section documents compatibility between mandoc and other
troff implementations, at this time limited to GNU troff
.Pq Qq groff .
.Pp
.Bl -dash -compact
.It
The \eN\(aq\(aq escape sequence is limited to printable characters; in
groff, it accepts arbitrary character numbers.
.It
In
.Fl T Ns Cm ascii ,
the
\e(ss, \e(nm, \e(nb, \e(nc, \e(ib, \e(ip, \e(pp, \e[sum], \e[product],
\e[coproduct], \e(gr, \e(\-h, and \e(a. special characters render
differently between mandoc and groff.
.It
In
.Fl T Ns Cm html
and
.Fl T Ns Cm xhtml ,
the \e(~=, \e(nb, and \e(nc special characters render differently
between mandoc and groff.
.It
The
.Fl T Ns Cm ps
and
.Fl T Ns Cm pdf
modes format like
.Fl T Ns Cm ascii
instead of rendering glyphs as in groff.
.It
The \e[radicalex], \e[sqrtex], and \e(ru special characters have been omitted
from mandoc either because they are poorly documented or they have no
known representation.
.El
.Sh SEE ALSO
.Xr mandoc 1 ,
.Xr man 7 ,
.Xr mdoc 7 ,
.Xr roff 7
.Sh AUTHORS
The
.Nm
manual page was written by
.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .
.Sh CAVEATS
The predefined string
.Sq \e*(Ba
mimics the behaviour of the
.Sq \&|
character in
.Xr mdoc 7 ;
thus, if you wish to render a vertical bar with no side effects, use
the
.Sq \e(ba
escape.
