1 MANDOC_CHAR(5)        Standards, Environments, and Macros       MANDOC_CHAR(5)
   2 
   3 NAME
   4      mandoc_char - mandoc special characters
   5 
   6 DESCRIPTION
   7      This page documents the mandoc_roff(5) escape sequences accepted by
   8      mandoc(1) to represent special characters in mdoc(5) and man(5)
   9      documents.
  10 
  11      The rendering depends on the mandoc(1) output mode; it can be inspected
  12      by calling man(1) on the mandoc_char manual page with different -T
  13      arguments.  In ASCII output, the rendering of some characters may be hard
  14      to interpret for the reader.  Many are rendered as descriptive strings
  15      like "<integral>",   "<degree>", or "<Gamma>", which     may look ugly, and
  16      many are replaced by similar ASCII characters.  In particular, accented
  17      characters are usually shown without the accent.  For that reason, try to
  18      avoid using any of the special characters documented here except those
  19      discussed in the DESCRIPTION, unless they are essential for explaining
  20      the subject matter at hand, for example when documenting complicated
  21      mathematical functions.
  22 
  23      In particular, in English manual pages, do not use special-character
  24      escape sequences to represent national language characters in author
  25      names; instead, provide ASCII transcriptions of the names.
  26 
  27    Dashes and Hyphens
  28      In typography there are different types of dashes of various width: the
  29      hyphen (-), the en-dash (-), the em-dash (--), and the mathematical minus
  30      sign (-).
  31 
  32      Hyphens are used for adjectives; to separate the two parts of a compound
  33      word; or to separate a word across two successive lines of text.  The
  34      hyphen does not need to be escaped:
  35 
  36            blue-eyed
  37            lorry-driver
  38 
  39      The en-dash is used to separate the two elements of a range, or can be
  40      used the same way as an em-dash.  It should be written as `\(en':
  41 
  42            pp. 95\(en97.
  43            Go away \(en or else!
  44 
  45      The em-dash can be used to show an interruption or can be used the same
  46      way as colons, semi-colons, or parentheses.  It should be written as
  47      `\(em':
  48 
  49            Three things \(em apples, oranges, and bananas.
  50            This is not that \(em rather, this is that.
  51 
  52      In mandoc_roff(5) documents, the minus sign is normally written as `\-'.
  53      In manual pages, some style guides recommend to also use `\-' if an ASCII
  54      0x2d "hyphen-minus" output glyph that can be copied and pasted is desired
  55      in output modes supporting it, for example in -T utf8 and -T html.  But
  56      currently, no practically relevant manual page formatter actually
  57      requires that subtlety, so in manual pages just write plain `-' to
  58      represent hyphen, minus, and hyphen-minus.
  59 
  60      If a word on a text input line contains a hyphen, a formatter may decide
  61      to insert an output line break after the hyphen if that helps filling the
  62      current output line, but the whole word would overflow the line.  If it
  63      is important that the word is not broken across lines in this way, a
  64      zero-width space (`\&') can be inserted before or after the hyphen.
  65      While mandoc(1) never breaks the output line after hyphens adjacent to a
  66      zero-width space, after any of the other dash- or hyphen-like characters
  67      represented by escape sequences, or after hyphens inside words in macro
  68      arguments, other software may not respect these rules and may break the
  69      line even in such cases.
  70 
  71      Some mandoc_roff(5) implementations contains dictionaries allowing to
  72      break the line at syllable boundaries even inside words that contain no
  73      hyphens.  Such automatic hyphenation is not supported by mandoc(1), which
  74      only breaks the line at whitespace, and inside words only after existing
  75      hyphens.
  76 
  77    Spaces
  78      To separate words in normal text, for indenting and alignment in literal
  79      context, and when none of the following special cases apply, just use the
  80      normal space character (` ').
  81 
  82      When filling text, output lines may be broken between words, i.e. at
  83      space characters.  To prevent a line break between two particular words,
  84      use the unpaddable non-breaking space escape sequence (`\ ') instead of
  85      the normal space character.  For example, the input string "number\ 1"
  86      will be kept together as "number 1" on the same output line.
  87 
  88      On request and macro lines, the normal space character serves as an
  89      argument delimiter.  To include whitespace into arguments, quoting is
  90      usually the best choice; see the MACRO SYNTAX section in mandoc_roff(5).
  91      In some cases, using the non-breaking space escape sequence (`\ ') may be
  92      preferable.
  93 
  94      To escape macro names and to protect whitespace at the end of input
  95      lines, the zero-width space (`\&')     is often useful.  For example, in
  96      mdoc(5), a normal space character can be displayed in single quotes in
  97      either of the following ways:
  98 
  99            .Sq " "
 100            .Sq \ \&
 101 
 102    Quotes
 103      On request and macro lines, the double-quote character (`"') is handled
 104      specially to allow quoting.  One way to prevent this special handling is
 105      by using the `\(dq' escape sequence.
 106 
 107      Note that on text lines, literal double-quote characters can be used
 108      verbatim.  All other quote-like characters can be used verbatim as well,
 109      even on request and macro lines.
 110 
 111    Accents
 112      In output modes supporting such special output characters, for example -T
 113      pdf, and sometimes less consistently in -T utf8, some mandoc_roff(5)
 114      formatters convert the following ASCII input characters to the following
 115      Unicode special output characters:
 116 
 117            `       U+2018    left single quotation mark
 118            '       U+2019    right single quotation mark
 119            ~       U+02DC    small tilde
 120            ^       U+02C6    modifier letter circumflex
 121 
 122      In prose, this automatic substitution is often desirable; but when these
 123      characters have to be displayed as plain ASCII characters, for example in
 124      source code samples, they require escaping to render as follows:
 125 
 126            \(ga    U+0060    grave accent
 127            \(aq    U+0027    apostrophe
 128            \(ti    U+007E    tilde
 129            \(ha    U+005E    circumflex accent
 130 
 131    Periods
 132      The period (`.') is handled specially at the beginning of an input line,
 133      where it introduces a mandoc_roff(5) request or a macro, and when
 134      appearing alone as a macro argument in mdoc(5).  In such situations,
 135      prepend a zero-width space (`\&.')     to make it behave like normal text.
 136 
 137      Do not use the `\.' escape sequence.  It does not prevent special
 138      handling of the period.
 139 
 140    Backslashes
 141      To include a literal backslash (`\') into the output, use the (`\e')
 142      escape sequence.
 143 
 144      Note that doubling it (`\\') is not the right way to output a backslash.
 145      Because mandoc(1) does not implement full mandoc_roff(5) functionality,
 146      it may work with mandoc(1), but it may have weird effects on complete
 147      mandoc_roff(5) implementations.
 148 
 149 SPECIAL CHARACTERS
 150      Special characters are encoded as `\X' (for a one-character escape),
 151      `\(XX' (two-character), and `\[N]' (N-character).  For details, see the
 152      Special Characters subsection of the mandoc_roff(5) manual.
 153 
 154      Spacing:
 155            Input    Description
 156            `\ '     unpaddable non-breaking space
 157            \~       paddable non-breaking space
 158            \0       unpaddable, breaking digit-width space
 159            \|       one-sixth \(em narrow space, zero width in nroff mode
 160            \^       one-twelfth \(em half-narrow space, zero width in nroff
 161            \&           zero-width space
 162            \%       zero-width space allowing hyphenation
 163 
 164      Lines:
 165            Input    Rendered    Description
 166            \(ba     |           bar
 167            \(br     |           box rule
 168            \(ul     _           underscore
 169            \(ru     _           underscore (width 0.5m)
 170            \(rn     -           overline
 171            \(bb     |           broken bar
 172            \(sl     /           forward slash
 173            \(rs     \           backward slash
 174 
 175      Text markers:
 176            Input    Rendered    Description
 177            \(ci     O           circle
 178            \(bu     o           bullet
 179            \(dd     <**>  double dagger
 180            \(dg     <*>           dagger
 181            \(lz     <>            lozenge
 182            \(sq     []          white square
 183            \(ps     <paragraph>   paragraph
 184            \(sc     <section>     section
 185            \(lh     <=               left hand
 186            \(rh     =>               right hand
 187            \(at     @           at
 188            \(sh     #           hash (pound)
 189            \(CR     <cr>  carriage return
 190            \(OK     \/          check mark
 191            \(CL     <club>        club suit
 192            \(SP     <spade>       spade suit
 193            \(HE     <heart>       heart suit
 194            \(DI     <diamond>     diamond suit
 195 
 196      Legal symbols:
 197            Input    Rendered    Description
 198            \(co     (C)         copyright
 199            \(rg     (R)         registered
 200            \(tm     tm          trademarked
 201 
 202      Punctuation:
 203            Input    Rendered    Description
 204            \(em     --          em-dash
 205            \(en     -           en-dash
 206            \(hy     -           hyphen
 207            \e       \           back-slash
 208            \.       .           period
 209            \(r!     !           upside-down exclamation
 210            \(r?     ?           upside-down question
 211 
 212      Quotes:
 213            Input    Rendered    Description
 214            \(Bq     ,,          right low double-quote
 215            \(bq     ,           right low single-quote
 216            \(lq     "           left double-quote
 217            \(rq     "           right double-quote
 218            \(oq     `           left single-quote
 219            \(cq     '           right single-quote
 220            \(aq     '           apostrophe quote (ASCII character)
 221            \(dq     "           double quote (ASCII character)
 222            \(Fo     <<            left guillemet
 223            \(Fc     >>            right guillemet
 224            \(fo     <                left single guillemet
 225            \(fc     >                right single guillemet
 226 
 227      Brackets:
 228            Input                Rendered    Description
 229            \(lB                 [           left bracket
 230            \(rB                 ]           right bracket
 231            \(lC                 {           left brace
 232            \(rC                 }           right brace
 233            \(la                 <        left angle
 234            \(ra                 >        right angle
 235            \(bv                 |           brace extension (special font)
 236            \[braceex]           |           brace extension
 237            \[bracketlefttp]     |           top-left hooked bracket
 238            \[bracketleftbt]     |           bottom-left hooked bracket
 239            \[bracketleftex]     |           left hooked bracket extension
 240            \[bracketrighttp]    |           top-right hooked bracket
 241            \[bracketrightbt]    |           bottom-right hooked bracket
 242            \[bracketrightex]    |           right hooked bracket extension
 243            \(lt                 ,-          top-left hooked brace
 244            \[bracelefttp]       ,-          top-left hooked brace
 245            \(lk                 {           mid-left hooked brace
 246            \[braceleftmid]      {           mid-left hooked brace
 247            \(lb                 `-          bottom-left hooked brace
 248            \[braceleftbt]       `-          bottom-left hooked brace
 249            \[braceleftex]       |           left hooked brace extension
 250            \(rt                 -.          top-left hooked brace
 251            \[bracerighttp]      -.          top-right hooked brace
 252            \(rk                 }           mid-right hooked brace
 253            \[bracerightmid]     }           mid-right hooked brace
 254            \(rb                 -'          bottom-right hooked brace
 255            \[bracerightbt]      -'          bottom-right hooked brace
 256            \[bracerightex]      |           right hooked brace extension
 257            \[parenlefttp]       /           top-left hooked parenthesis
 258            \[parenleftbt]       \           bottom-left hooked parenthesis
 259            \[parenleftex]       |           left hooked parenthesis extension
 260            \[parenrighttp]      \           top-right hooked parenthesis
 261            \[parenrightbt]      /           bottom-right hooked parenthesis
 262            \[parenrightex]      |           right hooked parenthesis extension
 263 
 264      Arrows:
 265            Input    Rendered    Description
 266            \(<-          <-               left arrow
 267            \(->          ->               right arrow
 268            \(<>       <->           left-right arrow
 269            \(da     v           down arrow
 270            \(ua     ^           up arrow
 271            \(va     ^v          up-down arrow
 272            \(lA     <=               left double-arrow
 273            \(rA     =>               right double-arrow
 274            \(hA     <=>           left-right double-arrow
 275            \(uA     ^           up double-arrow
 276            \(dA     v           down double-arrow
 277            \(vA     ^=v         up-down double-arrow
 278            \(an     -           horizontal arrow extension
 279 
 280      Logical:
 281            Input    Rendered    Description
 282            \(AN     ^           logical and
 283            \(OR     v           logical or
 284            \[tno]   ~           logical not (text font)
 285            \(no     ~           logical not (special font)
 286            \(te     <there exists>
 287                                 existential quantifier
 288            \(fa     <for all>     universal quantifier
 289            \(st     <such that>   such that
 290            \(tf     <therefore>   therefore
 291            \(3d     <therefore>   therefore
 292            \(or     |           bitwise or
 293 
 294      Mathematical:
 295            Input            Rendered    Description
 296            \-               -           minus (text font)
 297            \(mi             -           minus (special font)
 298            +                +           plus (text font)
 299            \(pl             +           plus (special font)
 300            \(-+             -+          minus-plus
 301            \[t+-]           +-          plus-minus (text font)
 302            \(+-             +-          plus-minus (special font)
 303            \(pc             .           center-dot
 304            \[tmu]           x           multiply (text font)
 305            \(mu             x           multiply (special font)
 306            \(c*             x           circle-multiply
 307            \(c+             +           circle-plus
 308            \[tdi]           /           divide (text font)
 309            \(di             /           divide (special font)
 310            \(f/             /           fraction
 311            \(**             *           asterisk
 312            \(<=                  <=               less-than-equal
 313            \(>=                  >=               greater-than-equal
 314            \(<<               <<            much less
 315            \(>>               >>            much greater
 316            \(eq             =           equal
 317            \(!=             !=          not equal
 318            \(==             ==          equivalent
 319            \(ne             !==         not equivalent
 320            \(ap             ~           tilde operator
 321            \(|=             -~          asymptotically equal
 322            \(=~             =~          approximately equal
 323            \(~~             ~~          almost equal
 324            \(~=             ~=          almost equal
 325            \(pt             <proportional to>
 326                                         proportionate
 327            \(es             {}          empty set
 328            \(mo             <element of>
 329                                         element
 330            \(nm             <not element of>
 331                                         not element
 332            \(sb             <proper subset>
 333                                         proper subset
 334            \(nb             <not subset>
 335                                         not subset
 336            \(sp             <proper superset>
 337                                         proper superset
 338            \(nc             <not superset>
 339                                         not superset
 340            \(ib             <subset or equal>
 341                                         reflexive subset
 342            \(ip             <superset or equal>
 343                                         reflexive superset
 344            \(ca             <intersection>
 345                                         intersection
 346            \(cu             <union>       union
 347            \(/_             <angle>       angle
 348            \(pp             <perpendicular>
 349                                         perpendicular
 350            \(is             <integral>    integral
 351            \[integral]      <integral>    integral
 352            \[sum]           <sum> summation
 353            \[product]       <product>     product
 354            \[coproduct]     <coproduct>   coproduct
 355            \(gr             <nabla>       gradient
 356            \(sr             <sqrt>        square root
 357            \[sqrt]          <sqrt>        square root
 358            \(lc             |~          left-ceiling
 359            \(rc             ~|          right-ceiling
 360            \(lf             |_          left-floor
 361            \(rf             _|          right-floor
 362            \(if             <infinity>    infinity
 363            \(Ah             <Aleph>       aleph
 364            \(Im             <Im>  imaginary
 365            \(Re             <Re>  real
 366            \(wp             P           Weierstrass p
 367            \(pd             <del> partial differential
 368            \(-h             /h          Planck constant over 2<pi>
 369            \[hbar]          /h          Planck constant over 2<pi>
 370            \(12             1/2         one-half
 371            \(14             1/4         one-fourth
 372            \(34             3/4         three-fourths
 373            \(18             1/8         one-eighth
 374            \(38             3/8         three-eighths
 375            \(58             5/8         five-eighths
 376            \(78             7/8         seven-eighths
 377            \(S1             ^1          superscript 1
 378            \(S2             ^2          superscript 2
 379            \(S3             ^3          superscript 3
 380 
 381      Ligatures:
 382            Input    Rendered    Description
 383            \(ff     ff          ff ligature
 384            \(fi     fi          fi ligature
 385            \(fl     fl          fl ligature
 386            \(Fi     ffi         ffi ligature
 387            \(Fl     ffl         ffl ligature
 388            \(AE     AE          AE
 389            \(ae     ae          ae
 390            \(OE     OE          OE
 391            \(oe     oe          oe
 392            \(ss     ss          German eszett
 393            \(IJ     IJ          IJ ligature
 394            \(ij     ij          ij ligature
 395 
 396      Accents:
 397            Input    Rendered    Description
 398            \(a"     "           Hungarian umlaut
 399            \(a-     -           macron
 400            \(a.     .           dotted
 401            \(a^     ^           circumflex
 402            \(aa     '           acute
 403            \'       '           acute
 404            \(ga     `           grave
 405            \`       `           grave
 406            \(ab     `           breve
 407            \(ac     ,           cedilla
 408            \(ad     "           dieresis
 409            \(ah     v           caron
 410            \(ao     o           ring
 411            \(a~     ~           tilde
 412            \(ho     ,           ogonek
 413            \(ha     ^           hat (ASCII character)
 414            \(ti     ~           tilde (ASCII character)
 415 
 416      Accented letters:
 417            Input    Rendered    Description
 418            \('A     A           acute A
 419            \('E     E           acute E
 420            \('I     I           acute I
 421            \('O     O           acute O
 422            \('U     U           acute U
 423            \('a     a           acute a
 424            \('e     e           acute e
 425            \('i     i           acute i
 426            \('o     o           acute o
 427            \('u     u           acute u
 428            \(`A     A           grave A
 429            \(`E     E           grave E
 430            \(`I     I           grave I
 431            \(`O     O           grave O
 432            \(`U     U           grave U
 433            \(`a     a           grave a
 434            \(`e     e           grave e
 435            \(`i     i           grave i
 436            \(`o     i           grave o
 437            \(`u     u           grave u
 438            \(~A     A           tilde A
 439            \(~N     N           tilde N
 440            \(~O     O           tilde O
 441            \(~a     a           tilde a
 442            \(~n     n           tilde n
 443            \(~o     o           tilde o
 444            \(:A     A           dieresis A
 445            \(:E     E           dieresis E
 446            \(:I     I           dieresis I
 447            \(:O     O           dieresis O
 448            \(:U     U           dieresis U
 449            \(:a     a           dieresis a
 450            \(:e     e           dieresis e
 451            \(:i     i           dieresis i
 452            \(:o     o           dieresis o
 453            \(:u     u           dieresis u
 454            \(:y     y           dieresis y
 455            \(^A     A           circumflex A
 456            \(^E     E           circumflex E
 457            \(^I     I           circumflex I
 458            \(^O     O           circumflex O
 459            \(^U     U           circumflex U
 460            \(^a     a           circumflex a
 461            \(^e     e           circumflex e
 462            \(^i     i           circumflex i
 463            \(^o     o           circumflex o
 464            \(^u     u           circumflex u
 465            \(,C     C           cedilla C
 466            \(,c     c           cedilla c
 467            \(/L     L           stroke L
 468            \(/l     l           stroke l
 469            \(/O     O           stroke O
 470            \(/o     o           stroke o
 471            \(oA     A           ring A
 472            \(oa     a           ring a
 473 
 474      Special letters:
 475            Input    Rendered    Description
 476            \(-D     Dh          Eth
 477            \(Sd     dh          eth
 478            \(TP     Th          Thorn
 479            \(Tp     th          thorn
 480            \(.i     i           dotless i
 481            \(.j     j           dotless j
 482 
 483      Currency:
 484            Input    Rendered    Description
 485            \(Do     $           dollar
 486            \(ct     c           cent
 487            \(Eu     EUR         Euro symbol
 488            \(eu     EUR         Euro symbol
 489            \(Ye     Y           yen
 490            \(Po     GBP         pound
 491            \(Cs     x           Scandinavian
 492            \(Fn     f           florin
 493 
 494      Units:
 495            Input    Rendered    Description
 496            \(de     <degree>      degree
 497            \(%0     <permille>    per-thousand
 498            \(fm     '           minute
 499            \(sd     ''          second
 500            \(mc     <micro>       micro
 501            \(Of     a           Spanish female ordinal
 502            \(Om     o           Spanish masculine ordinal
 503 
 504      Greek letters:
 505            Input    Rendered    Description
 506            \(*A     A           Alpha
 507            \(*B     B           Beta
 508            \(*G     <Gamma>       Gamma
 509            \(*D     <Delta>       Delta
 510            \(*E     E           Epsilon
 511            \(*Z     Z           Zeta
 512            \(*Y     H           Eta
 513            \(*H     <Theta>       Theta
 514            \(*I     I           Iota
 515            \(*K     K           Kappa
 516            \(*L     <Lambda>      Lambda
 517            \(*M     M           Mu
 518            \(*N     N           Nu
 519            \(*C     <Xi>  Xi
 520            \(*O     O           Omicron
 521            \(*P     <Pi>  Pi
 522            \(*R     P           Rho
 523            \(*S     <Sigma>       Sigma
 524            \(*T     T           Tau
 525            \(*U     Y           Upsilon
 526            \(*F     <Phi> Phi
 527            \(*X     X           Chi
 528            \(*Q     <Psi> Psi
 529            \(*W     <Omega>       Omega
 530            \(*a     <alpha>       alpha
 531            \(*b     <beta>        beta
 532            \(*g     <gamma>       gamma
 533            \(*d     <delta>       delta
 534            \(*e     <epsilon>     epsilon
 535            \(*z     <zeta>        zeta
 536            \(*y     <eta> eta
 537            \(*h     <theta>       theta
 538            \(*i     <iota>        iota
 539            \(*k     <kappa>       kappa
 540            \(*l     <lambda>      lambda
 541            \(*m     <mu>  mu
 542            \(*n     <nu>  nu
 543            \(*c     <xi>  xi
 544            \(*o     o           omicron
 545            \(*p     <pi>  pi
 546            \(*r     <rho> rho
 547            \(*s     <sigma>       sigma
 548            \(*t     <tau> tau
 549            \(*u     <upsilon>     upsilon
 550            \(*f     <phi> phi
 551            \(*x     <chi> chi
 552            \(*q     <psi> psi
 553            \(*w     <omega>       omega
 554            \(+h     <theta>       theta variant
 555            \(+f     <phi> phi variant
 556            \(+p     <pi>  pi variant
 557            \(+e     <epsilon>     epsilon variant
 558            \(ts     <sigma>       sigma terminal
 559 
 560 PREDEFINED STRINGS
 561      Predefined strings are inherited from the macro packages of historical
 562      troff implementations.  They are not recommended for use, as they differ
 563      across implementations.  Manuals using these predefined strings are
 564      almost certainly not portable.
 565 
 566      Their syntax is similar to special characters, using `\*X' (for a
 567      one-character escape), `\*(XX' (two-character), and `\*[N]'
 568      (N-character).  For details, see the Predefined Strings subsection of the
 569      mandoc_roff(5) manual.
 570 
 571            Input    Rendered    Description
 572            \*(Ba    |           vertical bar
 573            \*(Ne    !=          not equal
 574            \*(Ge    >=               greater-than-equal
 575            \*(Le    <=               less-than-equal
 576            \*(Gt    >                greater-than
 577            \*(Lt    <                less-than
 578            \*(Pm    +-          plus-minus
 579            \*(If    infinity    infinity
 580            \*(Pi    pi          pi
 581            \*(Na    NaN         NaN
 582            \*(Am    &               ampersand
 583            \*R      (R)         restricted mark
 584            \*(Tm    (Tm)        trade mark
 585            \*q      "           double-quote
 586            \*(Rq    "           right-double-quote
 587            \*(Lq    "           left-double-quote
 588            \*(lp    (           right-parenthesis
 589            \*(rp    )           left-parenthesis
 590            \*(lq    "           left double-quote
 591            \*(rq    "           right double-quote
 592            \*(ua    ^           up arrow
 593            \*(va    ^v          up-down arrow
 594            \*(<=    <=            less-than-equal
 595            \*(>=    >=            greater-than-equal
 596            \*(aa    '           acute
 597            \*(ga    `           grave
 598            \*(Px    POSIX       POSIX standard name
 599            \*(Ai    ANSI        ANSI standard name
 600 
 601 UNICODE CHARACTERS
 602      The escape sequences
 603 
 604            \[uXXXX] and \C'uXXXX'
 605 
 606      are interpreted as Unicode codepoints.  The codepoint must be in the
 607      range above U+0080 and less than U+10FFFF.  For compatibility, the
 608      hexadecimal digits `A' to `F' must be given as uppercase characters, and
 609      points must be zero-padded to four characters; if greater than four
 610      characters, no zero padding is allowed.  Unicode surrogates are not
 611      allowed.
 612 
 613 NUMBERED CHARACTERS
 614      For backward compatibility with existing manuals, mandoc(1) also supports
 615      the
 616 
 617            \N'number'
 618 
 619      escape sequence, inserting the character number from the current
 620      character set into the output.  Of course, this is inherently non-
 621      portable and is already marked as deprecated in the Heirloom roff manual.
 622      For example, do not use \N'34', use \(dq, or even the plain `"' character
 623      where possible.
 624 
 625 COMPATIBILITY
 626      This section documents compatibility between mandoc and other troff
 627      implementations, at this time limited to GNU troff ("groff").
 628 
 629      -   The \N'' escape sequence is limited to printable characters; in
 630          groff, it accepts arbitrary character numbers.
 631      -   In -Tascii, the \(ss, \(nm, \(nb, \(nc, \(ib, \(ip, \(pp, \[sum],
 632          \[product], \[coproduct], \(gr, \(-h, and \(a. special characters
 633          render differently between mandoc and groff.
 634      -   In -Thtml, the \(~=, \(nb, and \(nc special characters render
 635          differently between mandoc and groff.
 636      -   The -Tps and -Tpdf modes format like -Tascii instead of rendering
 637          glyphs as in groff.
 638      -   The \[radicalex], \[sqrtex], and \(ru special characters have been
 639          omitted from mandoc either because they are poorly documented or they
 640          have no known representation.
 641 
 642 SEE ALSO
 643      mandoc(1), man(5), mandoc_roff(5), mdoc(5)
 644 
 645 AUTHORS
 646      The mandoc_char manual page was written by Kristaps Dzonsons
 647      <kristaps@bsd.lv>.
 648 
 649 CAVEATS
 650      The predefined string `\*(Ba' mimics the behaviour of the `|' character
 651      in mdoc(5); thus, if you wish to render a vertical bar with no side
 652      effects, use the `\(ba' escape.
 653 
 654 illumos                         August 8, 2018                         illumos