roff.7

   1 .\"     $Id: roff.7,v 1.6 2010/05/24 22:25:58 schwarze Exp $
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   3 .\" Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
   4 .\"
   5 .\" Permission to use, copy, modify, and distribute this software for any
   6 .\" purpose with or without fee is hereby granted, provided that the above
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  17 .Dd $Mdocdate: May 24 2010 $
  18 .Dt ROFF 7
  19 .Os
  20 .Sh NAME
  21 .Nm roff
  22 .Nd roff language reference
  23 .Sh DESCRIPTION
  24 The
  25 .Nm roff
  26 language is a general-purpose text-formatting language.  The purpose of
  27 this document is to consistently describe those language constructs
  28 accepted by the
  29 .Xr mandoc 1
  30 utility.  It is a work in progress.
  31 .Pp
  32 An
  33 .Nm
  34 document follows simple rules:  lines beginning with the control
  35 characters
  36 .Sq \.
  37 or
  38 .Sq \(aq
  39 are parsed for macros.  Other lines are interpreted within the scope of
  40 prior macros:
  41 .Bd -literal -offset indent
  42 \&.xx Macro lines change control state.
  43 Other lines are interpreted within the current state.
  44 .Ed
  45 .Sh LANGUAGE SYNTAX
  46 .Nm
  47 documents may contain only graphable 7-bit ASCII characters, the space
  48 character, and, in certain circumstances, the tab character.  All
  49 manuals must have
  50 .Ux
  51 line terminators.
  52 .Sh MACRO SYNTAX
  53 Macros are arbitrary in length and begin with a control character ,
  54 .Sq \.
  55 or
  56 .Sq \(aq ,
  57 at the beginning of the line.
  58 An arbitrary amount of whitespace may sit between the control character
  59 and the macro name.
  60 Thus, the following are equivalent:
  61 .Bd -literal -offset indent
  62 \&.if
  63 \&.\ \ \ \&if
  64 .Ed
  65 .Sh REFERENCE
  66 This section is a canonical reference of all macros, arranged
  67 alphabetically.
  68 .Ss \&am
  69 The syntax of this macro is the same as that of
  70 .Sx \&ig ,
  71 except that a leading argument must be specified.
  72 It is ignored, as are its children.
  73 .Ss \&ami
  74 The syntax of this macro is the same as that of
  75 .Sx \&ig ,
  76 except that a leading argument must be specified.
  77 It is ignored, as are its children.
  78 .Ss \&am1
  79 The syntax of this macro is the same as that of
  80 .Sx \&ig ,
  81 except that a leading argument must be specified.
  82 It is ignored, as are its children.
  83 .Ss \&de
  84 The syntax of this macro is the same as that of
  85 .Sx \&ig ,
  86 except that a leading argument must be specified.
  87 It is ignored, as are its children.
  88 .Ss \&dei
  89 The syntax of this macro is the same as that of
  90 .Sx \&ig ,
  91 except that a leading argument must be specified.
  92 It is ignored, as are its children.
  93 .Ss \&ds
  94 Define a string.
  95 This macro is intended to have two arguments,
  96 the name of the string to define and its content.
  97 Currently, it is ignored including its arguments,
  98 and the number of arguments is not checked.
  99 .Ss \&de1
 100 The syntax of this macro is the same as that of
 101 .Sx \&ig ,
 102 except that a leading argument must be specified.
 103 It is ignored, as are its children.
 104 .Ss \&el
 105 The
 106 .Qq else
 107 half of an if/else conditional.
 108 Pops a result off the stack of conditional evaluations pushed by
 109 .Sx \&ie
 110 and uses it as its conditional.
 111 If no stack entries are present (e.g., due to no prior
 112 .Sx \&ie
 113 calls)
 114 then false is assumed.
 115 The syntax of this macro is similar to
 116 .Sx \&if
 117 except that the conditional is missing.
 118 .Ss \&ie
 119 The
 120 .Qq if
 121 half of an if/else conditional.
 122 The result of the conditional is pushed into a stack used by subsequent
 123 invocations of
 124 .Sx \&el ,
 125 which may be separated by any intervening input (or not exist at all).
 126 Its syntax is equivalent to
 127 .Sx \&if .
 128 .Ss \&if
 129 Begins a conditional that always evaluates to false.
 130 If a conditional is false, its children are not processed, but are
 131 syntactically interpreted to preserve the integrity of the input
 132 document.
 133 Thus,
 134 .Pp
 135 .D1 \&.if t \e .ig
 136 .Pp
 137 will discard the
 138 .Sq \&.ig ,
 139 which may lead to interesting results, but
 140 .Pp
 141 .D1 \&.if t \e .if t \e{\e
 142 .Pp
 143 will continue to syntactically interpret to the block close of the final
 144 conditional.
 145 Sub-conditionals, in this case, obviously inherit the truth value of
 146 the parent.
 147 This macro has the following syntax:
 148 .Pp
 149 .Bd -literal -offset indent -compact
 150 \&.if COND \e{\e
 151 BODY...
 152 \&.\e}
 153 .Ed
 154 .Bd -literal -offset indent -compact
 155 \&.if COND \e{ BODY
 156 BODY... \e}
 157 .Ed
 158 .Bd -literal -offset indent -compact
 159 \&.if COND \e{ BODY
 160 BODY...
 161 \&.\e}
 162 .Ed
 163 .Bd -literal -offset indent -compact
 164 \&.if COND \e
 165 BODY
 166 .Ed
 167 .Pp
 168 COND is a conditional (for the time being, this always evaluates to
 169 false).
 170 .Pp
 171 If the BODY section is begun by an escaped brace
 172 .Sq \e{ ,
 173 scope continues until a closing-brace macro
 174 .Sq \.\e} .
 175 If the BODY is not enclosed in braces, scope continues until the next
 176 macro or word.
 177 If the COND is followed by a BODY on the same line, whether after a
 178 brace or not, then macros
 179 .Em must
 180 begin with a control character.
 181 It is generally more intuitive, in this case, to write
 182 .Bd -literal -offset indent
 183 \&.if COND \e{\e
 184 \&.foo
 185 bar
 186 \&.\e}
 187 .Ed
 188 .Pp
 189 than having the macro follow as
 190 .Pp
 191 .D1 \&.if COND \e{ .foo
 192 .Pp
 193 The scope of a conditional is always parsed, but only executed if the
 194 conditional evaluates to true.
 195 .Pp
 196 Note that text subsequent a
 197 .Sq \&.\e}
 198 macro is discarded.
 199 Furthermore, if an explicit closing sequence
 200 .Sq \e}
 201 is specified in a free-form line, the entire line is accepted within the
 202 scope of the prior macro, not only the text preceding the close.
 203 .Ss \&ig
 204 Ignore input.
 205 Accepts the following syntax:
 206 .Pp
 207 .Bd -literal -offset indent -compact
 208 \&.ig
 209 BODY...
 210 \&..
 211 .Ed
 212 .Bd -literal -offset indent -compact
 213 \&.ig END
 214 BODY...
 215 \&.END
 216 .Ed
 217 .Pp
 218 In the first case, input is ignored until a
 219 .Sq \&..
 220 macro is encountered on its own line.
 221 In the second case, input is ignored until a
 222 .Sq \&.END
 223 is encountered.
 224 Text subsequent the
 225 .Sq \&.END
 226 or
 227 .Sq \&..
 228 is discarded.
 229 .Pp
 230 Do not use the escape
 231 .Sq \e
 232 anywhere in the definition of END.
 233 It causes very strange behaviour.
 234 Furthermore, if you redefine a
 235 .Nm
 236 macro, such as
 237 .Pp
 238 .D1 \&.ig if
 239 .Pp
 240 the subsequent invocation of
 241 .Sx \&if
 242 will first signify the end of comment, then be invoked as a macro.
 243 This behaviour really shouldn't be counted upon.
 244 .Ss \&rm
 245 Remove a request, macro or string.
 246 This macro is intended to have one argument,
 247 the name of the request, macro or string to be undefined.
 248 Currently, it is ignored including its arguments,
 249 and the number of arguments is not checked.
 250 .Ss \&tr
 251 Output character translation.
 252 This macro is intended to have one argument,
 253 consisting of an even number of characters.
 254 Currently, it is ignored including its arguments,
 255 and the number of arguments is not checked.
 256 .Sh COMPATIBILITY
 257 This section documents compatibility between mandoc and other other
 258 troff implementations, at this time limited to GNU troff
 259 .Pq Qq groff .
 260 The term
 261 .Qq historic groff
 262 refers to groff versions before the
 263 .Pa doc.tmac
 264 file re-write
 265 .Pq somewhere between 1.15 and 1.19 .
 266 .Pp
 267 .Bl -dash -compact
 268 .It
 269 Historic groff did not accept white-space buffering the custom END tag
 270 for the
 271 .Sx \&ig
 272 macro.
 273 .It
 274 The
 275 .Sx \&if
 276 and family would print funny white-spaces with historic groff when
 277 depending on next-line syntax.
 278 .El
 279 .Sh AUTHORS
 280 The
 281 .Nm
 282 reference was written by
 283 .An Kristaps Dzonsons Aq kristaps@bsd.lv .