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ROFF(7)                Miscellaneous Information Manual                ROFF(7)

NAME
     roff - roff language reference for mandoc

DESCRIPTION
     The roff language is a general purpose text formatting language.  Since
     traditional implementations of the mdoc(7) and man(7) manual formatting
     languages are based on it, many real-world manuals use small numbers of
     roff requests and escape sequences intermixed with their mdoc(7) or
     man(7) code.  To properly format such manuals, the mandoc(1) utility
     supports a tiny subset of roff requests and escapes.  Only these requests
     and escapes supported by mandoc(1) are documented in the present manual,
     together with the basic language syntax shared by roff, mdoc(7), and
     man(7).  For complete roff manuals, consult the SEE ALSO section.

     Input lines beginning with the control character `.' are parsed for
     requests and macros.  Such lines are called "request lines" or "macro
     lines", respectively.  Requests change the processing state and
     manipulate the formatting; some macros also define the document structure
     and produce formatted output.  The single quote ("'") is accepted as an
     alternative control character, treated by mandoc(1) just like `.'

     Lines not beginning with control characters are called "text lines".
     They provide free-form text to be printed; the formatting of the text
     depends on the respective processing context.

LANGUAGE SYNTAX
     roff documents may contain only graphable 7-bit ASCII characters, the
     space character, and, in certain circumstances, the tab character.  The
     backslash character `\' indicates the start of an escape sequence, used
     for example for Comments, Special Characters, Predefined Strings, and
     user-defined strings defined using the ds request.  For a listing of
     escape sequences, consult the ESCAPE SEQUENCE REFERENCE below.

   Comments
     Text following an escaped double-quote `\"', whether in a request, macro,
     or text line, is ignored to the end of the line.  A request line
     beginning with a control character and comment escape `.\"' is also
     ignored.  Furthermore, request lines with only a control character and
     optional trailing whitespace are stripped from input.

     Examples:
           .\" This is a comment line.
           .\" The next line is ignored:
           .
           .Sh EXAMPLES \" This is a comment, too.
           example text \" And so is this.

   Special Characters
     Special characters are used to encode special glyphs and are rendered
     differently across output media.  They may occur in request, macro, and
     text lines.  Sequences begin with the escape character `\' followed by
     either an open-parenthesis `(' for two-character sequences; an open-
     bracket `[' for n-character sequences (terminated at a close-bracket
     `]'); or a single one character sequence.

     Examples:
           \(em    Two-letter em dash escape.
           \e      One-letter backslash escape.

     See mandoc_char(7) for a complete list.

   Text Decoration
     Terms may be text-decorated using the `\f' escape followed by an
     indicator: B (bold), I (italic), R (regular), or P (revert to previous
     mode).  A numerical representation 3, 2, or 1 (bold, italic, and regular,
     respectively) may be used instead.  The indicator or numerical
     representative may be preceded by C (constant-width), which is ignored.

     The two-character indicator `BI' requests a font that is both bold and
     italic.  It may not be portable to old roff implementations.

     Examples:
           \fBbold\fR
                   Write in bold, then switch to regular font mode.
           \fIitalic\fP
                   Write in italic, then return to previous font mode.
           \f(BIbold italic\fP
                   Write in bboolldd iittaalliicc, then return to previous font mode.

     Text decoration is not recommended for mdoc(7), which encourages semantic
     annotation.

   Predefined Strings
     Predefined strings, like Special Characters, mark special output glyphs.
     Predefined strings are escaped with the slash-asterisk, `\*': single-
     character `\*X', two-character `\*(XX', and N-character `\*[N]'.

     Examples:
           \*(Am   Two-letter ampersand predefined string.
           \*q     One-letter double-quote predefined string.

     Predefined strings are not recommended for use, as they differ across
     implementations.  Those supported by mandoc(1) are listed in
     mandoc_char(7).  Manuals using these predefined strings are almost
     certainly not portable.

   Whitespace
     Whitespace consists of the space character.  In text lines, whitespace is
     preserved within a line.  In request and macro lines, whitespace delimits
     arguments and is discarded.

     Unescaped trailing spaces are stripped from text line input unless in a
     literal context.  In general, trailing whitespace on any input line is
     discouraged for reasons of portability.  In the rare case that a blank
     character is needed at the end of an input line, it may be forced by
     `\ \&'.

     Literal space characters can be produced in the output using escape
     sequences.  In macro lines, they can also be included in arguments using
     quotation; see MACRO SYNTAX for details.

     Blank text lines, which may include whitespace, are only permitted within
     literal contexts.  If the first character of a text line is a space, that
     line is printed with a leading newline.

   Scaling Widths
     Many requests and macros support scaled widths for their arguments.  The
     syntax for a scaled width is `[+-]?[0-9]*.[0-9]*[:unit:]', where a
     decimal must be preceded or followed by at least one digit.  Negative
     numbers, while accepted, are truncated to zero.

     The following scaling units are accepted:

           c       centimetre
           i       inch
           P       pica (~1/6 inch)
           p       point (~1/72 inch)
           f       scale `u' by 65536
           v       default vertical span
           m       width of rendered `m' (em) character
           n       width of rendered `n' (en) character
           u       default horizontal span for the terminal
           M       mini-em (~1/100 em)

     Using anything other than `m', `n', or `v' is necessarily non-portable
     across output media.  See COMPATIBILITY.

     If a scaling unit is not provided, the numerical value is interpreted
     under the default rules of `v' for vertical spaces and `u' for horizontal
     ones.

     Examples:
           .Bl -tag -width 2i  two-inch tagged list indentation in mdoc(7)
           .HP 2i              two-inch tagged list indentation in man(7)
           .sp 2v              two vertical spaces

   Sentence Spacing
     Each sentence should terminate at the end of an input line.  By doing
     this, a formatter will be able to apply the proper amount of spacing
     after the end of sentence (unescaped) period, exclamation mark, or
     question mark followed by zero or more non-sentence closing delimiters
     (`)', `]', `'', `"').

     The proper spacing is also intelligently preserved if a sentence ends at
     the boundary of a macro line.

     Examples:
           Do not end sentences mid-line like this.  Instead,
           end a sentence like this.
           A macro would end like this:
           .Xr mandoc 1 .

REQUEST SYNTAX
     A request or macro line consists of:

     1.   the control character `.' or `'' at the beginning of the line,
     2.   optionally an arbitrary amount of whitespace,
     3.   the name of the request or the macro, which is one word of arbitrary
          length, terminated by whitespace,
     4.   and zero or more arguments delimited by whitespace.

     Thus, the following request lines are all equivalent:

           .ig end
           .ig    end
           .   ig end

MACRO SYNTAX
     Macros are provided by the mdoc(7) and man(7) languages and can be
     defined by the de request.  When called, they follow the same syntax as
     requests, except that macro arguments may optionally be quoted by
     enclosing them in double quote characters (`"').  Quoted text, even if it
     contains whitespace or would cause a macro invocation when unquoted, is
     always considered literal text.  Inside quoted text, pairs of double
     quote characters (`""') resolve to single double quote characters.

     To be recognised as the beginning of a quoted argument, the opening quote
     character must be preceded by a space character.  A quoted argument
     extends to the next double quote character that is not part of a pair, or
     to the end of the input line, whichever comes earlier.  Leaving out the
     terminating double quote character at the end of the line is discouraged.
     For clarity, if more arguments follow on the same input line, it is
     recommended to follow the terminating double quote character by a space
     character; in case the next character after the terminating double quote
     character is anything else, it is regarded as the beginning of the next,
     unquoted argument.

     Both in quoted and unquoted arguments, pairs of backslashes (`\\')
     resolve to single backslashes.  In unquoted arguments, space characters
     can alternatively be included by preceding them with a backslash (`\ '),
     but quoting is usually better for clarity.

     Examples:
           .Fn strlen "const char *s"
                   Group arguments "const char *s" into one function argument.
                   If unspecified, "const", "char", and "*s" would be
                   considered separate arguments.
           .Op "Fl a"
                   Consider "Fl a" as literal text instead of a flag macro.

REQUEST REFERENCE
     The mandoc(1) roff parser recognises the following requests.  For
     requests marked as "ignored" or "unsupported", any arguments are ignored,
     and the number of arguments is not checked.

   ab
     Abort processing.  Currently unsupported.

   ad
     Set line adjustment mode.  It takes one argument to select normal, left,
     right, or center adjustment for subsequent text.  Currently ignored.

   af
     Assign an output format to a number register.  Currently ignored.

   aln
     Create an alias for a number register.  Currently unsupported.

   als
     Create an alias for a request, string, macro, or diversion.  Currently
     unsupported.

   am
     Append to a macro definition.  The syntax of this request is the same as
     that of de.

   am1
     Append to a macro definition, switching roff compatibility mode off
     during macro execution (groff extension).  The syntax of this request is
     the same as that of de1.  Since mandoc(1) does not implement roff
     compatibility mode at all, it handles this request as an alias for am.

   ami
     Append to a macro definition, specifying the macro name indirectly (groff
     extension).  The syntax of this request is the same as that of dei.

   ami1
     Append to a macro definition, specifying the macro name indirectly and
     switching roff compatibility mode off during macro execution (groff
     extension).  The syntax of this request is the same as that of dei1.
     Since mandoc(1) does not implement roff compatibility mode at all, it
     handles this request as an alias for ami.

   as
     Append to a user-defined string.  The syntax of this request is the same
     as that of ds.  If a user-defined string with the specified name does not
     yet exist, it is set to the empty string before appending.

   as1
     Append to a user-defined string, switching roff compatibility mode off
     during macro execution (groff extension).  The syntax of this request is
     the same as that of ds1.  Since mandoc(1) does not implement roff
     compatibility mode at all, it handles this request as an alias for as.

   asciify
     Fully unformat a diversion.  Currently unsupported.

   backtrace
     Print a backtrace of the input stack.  This is a groff extension and
     currently ignored.

   bd
     Artificially embolden by repeated printing with small shifts.  Currently
     ignored.

   bleedat
     Set the BleedBox page parameter for PDF generation.  This is a Heirloom
     extension and currently ignored.

   blm
     Set a blank line trap.  Currently unsupported.

   box
     Begin a diversion without including a partially filled line.  Currently
     unsupported.

   boxa
     Add to a diversion without including a partially filled line.  Currently
     unsupported.

   bp
     Begin new page.  Currently ignored.

   BP
     Define a frame and place a picture in it.  This is a Heirloom extension
     and currently unsupported.

   br
     Break the output line.  See man(7) and mdoc(7).

   break
     Break out of a while loop.  Currently unsupported.

   breakchar
     Optional line break characters.  This is a Heirloom extension and
     currently ignored.

   brnl
     Break output line after next N input lines.  This is a Heirloom extension
     and currently ignored.

   brp
     Break and spread output line.  Currently, this is implemented as an alias
     for br.

   brpnl
     Break and spread output line after next N input lines.  This is a
     Heirloom extension and currently ignored.

   c2
     Change the no-break control character.  Currently unsupported.

   cc
     Change the control character.  Its syntax is as follows:

           .cc [c]

     If c is not specified, the control character is reset to `.'.  Trailing
     characters are ignored.

   ce
     Center some lines.  It takes one integer argument, specifying how many
     lines to center.  Currently ignored.

   cf
     Output the contents of a file.  Ignored because insecure.

   cflags
     Set character flags.  This is a groff extension and currently ignored.

   ch
     Change a trap location.  Currently ignored.

   char
     Define a new glyph.  Currently unsupported.

   chop
     Remove the last character from a macro, string, or diversion.  Currently
     unsupported.

   class
     Define a character class.  This is a groff extension and currently
     ignored.

   close
     Close an open file.  Ignored because insecure.

   CL
     Print text in color.  This is a Heirloom extension and currently
     unsupported.

   color
     Activate or deactivate colors.  This is a groff extension and currently
     ignored.

   composite
     Define a name component for composite glyph names.  This is a groff
     extension and currently unsupported.

   continue
     Immediately start the next iteration of a while loop.  Currently
     unsupported.

   cp
     Switch roff compatibility mode on or off.  Currently ignored.

   cropat
     Set the CropBox page parameter for PDF generation.  This is a Heirloom
     extension and currently ignored.

   cs
     Constant character spacing mode.  Currently ignored.

   cu
     Underline including whitespace.  Currently ignored.

   da
     Append to a diversion.  Currently unsupported.

   dch
     Change a trap location in the current diversion.  This is a Heirloom
     extension and currently unsupported.

   de
     Define a roff macro.  Its syntax can be either

           .de name
           macro definition
           ..

     or

           .de name end
           macro definition
           .end

     Both forms define or redefine the macro name to represent the macro
     definition, which may consist of one or more input lines, including the
     newline characters terminating each line, optionally containing calls to
     roff requests, roff macros or high-level macros like man(7) or mdoc(7)
     macros, whichever applies to the document in question.

     Specifying a custom end macro works in the same way as for ig; namely,
     the call to `.end' first ends the macro definition, and after that, it is
     also evaluated as a roff request or roff macro, but not as a high-level
     macro.

     The macro can be invoked later using the syntax

           .name [argument [argument ...]]

     Regarding argument parsing, see MACRO SYNTAX above.

     The line invoking the macro will be replaced in the input stream by the
     macro definition, replacing all occurrences of \\$N, where N is a digit,
     by the Nth argument.  For example,

           .de ZN
           \fI\^\\$1\^\fP\\$2
           ..
           .ZN XtFree .

     produces

           \fI\^XtFree\^\fP.

     in the input stream, and thus in the output: XtFree.  Each occurrence of
     \\$* is replaced with all the arguments, joined together with single
     blank characters.

     Since macros and user-defined strings share a common string table,
     defining a macro name clobbers the user-defined string name, and the
     macro definition can also be printed using the `\*' string interpolation
     syntax described below ds, but this is rarely useful because every macro
     definition contains at least one explicit newline character.

     In order to prevent endless recursion, both groff and mandoc(1) limit the
     stack depth for expanding macros and strings to a large, but finite
     number, and mandoc(1) also limits the length of the expanded input line.
     Do not rely on the exact values of these limits.

   de1
     Define a roff macro that will be executed with roff compatibility mode
     switched off during macro execution.  This is a groff extension.  Since
     mandoc(1) does not implement roff compatibility mode at all, it handles
     this request as an alias for de.

   defcolor
     Define a color name.  This is a groff extension and currently ignored.

   dei
     Define a roff macro, specifying the macro name indirectly (groff
     extension).  The syntax of this request is the same as that of de.  The
     request

           .dei name [end]

     has the same effect as:

           .de \*[name] [\*[end]]

   dei1
     Define a roff macro that will be executed with roff compatibility mode
     switched off during macro execution, specifying the macro name indirectly
     (groff extension).  Since mandoc(1) does not implement roff compatibility
     mode at all, it handles this request as an alias for dei.

   device
     This request only makes sense with the groff-specific intermediate output
     format and is unsupported.

   devicem
     This request only makes sense with the groff-specific intermediate output
     format and is unsupported.

   di
     Begin a diversion.  Currently unsupported.

   do
     Execute roff request or macro line with compatibility mode disabled.
     Currently unsupported.

   ds
     Define a user-defined string.  Its syntax is as follows:

           .ds name ["]string

     The name and string arguments are space-separated.  If the string begins
     with a double-quote character, that character will not be part of the
     string.  All remaining characters on the input line form the string,
     including whitespace and double-quote characters, even trailing ones.

     The string can be interpolated into subsequent text by using \*[name] for
     a name of arbitrary length, or \*(NN or \*N if the length of name is two
     or one characters, respectively.  Interpolation can be prevented by
     escaping the leading backslash; that is, an asterisk preceded by an even
     number of backslashes does not trigger string interpolation.

     Since user-defined strings and macros share a common string table,
     defining a string name clobbers the macro name, and the name used for
     defining a string can also be invoked as a macro, in which case the
     following input line will be appended to the string, forming a new input
     line passed to the roff parser.  For example,

           .ds badidea .S
           .badidea
           H SYNOPSIS

     invokes the SH macro when used in a man(7) document.  Such abuse is of
     course strongly discouraged.

   ds1
     Define a user-defined string that will be expanded with roff
     compatibility mode switched off during string expansion.  This is a groff
     extension.  Since mandoc(1) does not implement roff compatibility mode at
     all, it handles this request as an alias for ds.

   dwh
     Set a location trap in the current diversion.  This is a Heirloom
     extension and currently unsupported.

   dt
     Set a trap within a diversion.  Currently unsupported.

   ec
     Change the escape character.  Currently unsupported.

   ecs
     Restore the escape character.  Currently unsupported.

   ecr
     Save the escape character.  Currently unsupported.

   el
     The "else" half of an if/else conditional.  Pops a result off the stack
     of conditional evaluations pushed by ie and uses it as its conditional.
     If no stack entries are present (e.g., due to no prior ie calls) then
     false is assumed.  The syntax of this request is similar to if except
     that the conditional is missing.

   em
     Set a trap at the end of input.  Currently unsupported.

   EN
     End an equation block.  See EQ.

   eo
     Disable the escape mechanism completely.  Currently unsupported.

   EP
     End a picture started by BP.  This is a Heirloom extension and currently
     unsupported.

   EQ
     Begin an equation block.  See eqn(7) for a description of the equation
     language.

   errprint
     Print a string like an error message.  This is a Heirloom extension and
     currently ignored.

   ev
     Switch to another environment.  Currently unsupported.

   evc
     Copy an environment into the current environment.  Currently unsupported.

   ex
     Abort processing and exit.  Currently unsupported.

   fallback
     Select the fallback sequence for a font.  This is a Heirloom extension
     and currently ignored.

   fam
     Change the font family.  Takes one argument specifying the font family to
     be selected.  It is a groff extension and currently ignored.

   fc
     Define a delimiting and a padding character for fields.  Currently
     unsupported.

   fchar
     Define a fallback glyph.  Currently unsupported.

   fcolor
     Set the fill color for \D objects.  This is a groff extension and
     currently ignored.

   fdeferlig
     Defer ligature building.  This is a Heirloom extension and currently
     ignored.

   feature
     Enable or disable an OpenType feature.  This is a Heirloom extension and
     currently ignored.

   fi
     Switch to fill mode.  See man(7).  Ignored in mdoc(7).

   fkern
     Control the use of kerning tables for a font.  This is a Heirloom
     extension and currently ignored.

   fl
     Flush output.  Currently ignored.

   flig
     Define ligatures.  This is a Heirloom extension and currently ignored.

   fp
     Assign font position.  Currently ignored.

   fps
     Mount a font with a special character map.  This is a Heirloom extension
     and currently ignored.

   fschar
     Define a font-specific fallback glyph.  This is a groff extension and
     currently unsupported.

   fspacewidth
     Set a font-specific width for the space character.  This is a Heirloom
     extension and currently ignored.

   fspecial
     Conditionally define a special font.  This is a groff extension and
     currently ignored.

   ft
     Change the font.  Its syntax is as follows:

           .ft [font]

     The following font arguments are supported:

           B, BI, 3, 4
                 switches to bold font

           I, 2  switches to underlined font

           R, CW, 1
                 switches to normal font

           P or no argument
                 switches back to the previous font

     This request takes effect only locally, may be overridden by macros and
     escape sequences, and is only supported in man(7) for now.

   ftr
     Translate font name.  This is a groff extension and currently ignored.

   fzoom
     Zoom font size.  Currently ignored.

   gcolor
     Set glyph color.  This is a groff extension and currently ignored.

   hc
     Set the hyphenation character.  Currently ignored.

   hcode
     Set hyphenation codes of characters.  Currently ignored.

   hidechar
     Hide characters in a font.  This is a Heirloom extension and currently
     ignored.

   hla
     Set hyphenation language.  This is a groff extension and currently
     ignored.

   hlm
     Set maximum number of consecutive hyphenated lines.  Currently ignored.

   hpf
     Load hyphenation pattern file.  This is a groff extension and currently
     ignored.

   hpfa
     Load hyphenation pattern file, appending to the current patterns.  This
     is a groff extension and currently ignored.

   hpfcode
     Define mapping values for character codes in hyphenation patterns.  This
     is a groff extension and currently ignored.

   hw
     Specify hyphenation points in words.  Currently ignored.

   hy
     Set automatic hyphenation mode.  Currently ignored.

   hylang
     Set hyphenation language.  This is a Heirloom extension and currently
     ignored.

   hylen
     Minimum word length for hyphenation.  This is a Heirloom extension and
     currently ignored.

   hym
     Set hyphenation margin.  This is a groff extension and currently ignored.

   hypp
     Define hyphenation penalties.  This is a Heirloom extension and currently
     ignored.

   hys
     Set hyphenation space.  This is a groff extension and currently ignored.

   ie
     The "if" half of an if/else conditional.  The result of the conditional
     is pushed into a stack used by subsequent invocations of el, which may be
     separated by any intervening input (or not exist at all).  Its syntax is
     equivalent to if.

   if
     Begins a conditional.  This request has the following syntax:

           .if COND BODY

           .if COND \{BODY
           BODY...\}

           .if COND \{\
           BODY...
           .\}

     COND is a conditional statement.  Currently, mandoc(1) supports the
     following subset of roff conditionals:

        If `!' is prefixed to COND, the condition is logically inverted.

        If the first character of COND is `n' (nroff mode) or `o' (odd page),
         COND evaluates to true.

        If the first character of COND is `c' (character available), `d'
         (string defined), `e' (even page), `t' (troff mode), or `v' (vroff
         mode), COND evaluates to false.

        If the first character of COND is `r', it evaluates to true if the
         rest of COND is the name of an existing number register; otherwise,
         it evaluates to false.

        If COND starts with a parenthesis or with an optionally signed
         integer number, it is evaluated according to the rules of Numerical
         expressions explained below.  It evaluates to true if the result is
         positive, or to false if the result is zero or negative.

        Otherwise, the first character of COND is regarded as a delimiter and
         COND evaluates to true if the string extending from its first to its
         second occurrence is equal to the string extending from its second to
         its third occurrence.

        If COND cannot be parsed, it evaluates to false.

     If a conditional is false, its children are not processed, but are
     syntactically interpreted to preserve the integrity of the input
     document.  Thus,

           .if t .ig

     will discard the `.ig', which may lead to interesting results, but

           .if t .if t \{\

     will continue to syntactically interpret to the block close of the final
     conditional.  Sub-conditionals, in this case, obviously inherit the truth
     value of the parent.

     If the BODY section is begun by an escaped brace `\{', scope continues
     until the end of the input line containing the matching closing-brace
     escape sequence `\}'.  If the BODY is not enclosed in braces, scope
     continues until the end of the line.  If the COND is followed by a BODY
     on the same line, whether after a brace or not, then requests and macros
     must begin with a control character.  It is generally more intuitive, in
     this case, to write

           .if COND \{\
           .foo
           bar
           .\}

     than having the request or macro follow as

           .if COND \{ .foo

     The scope of a conditional is always parsed, but only executed if the
     conditional evaluates to true.

     Note that the `\}' is converted into a zero-width escape sequence if not
     passed as a standalone macro `.\}'.  For example,

           .Fl a \} b

     will result in `\}' being considered an argument of the `Fl' macro.

   ig
     Ignore input.  Its syntax can be either

           .ig
           ignored text
           ..

     or

           .ig end
           ignored text
           .end

     In the first case, input is ignored until a `..' request is encountered
     on its own line.  In the second case, input is ignored until the
     specified `.end' macro is encountered.  Do not use the escape character
     `\' anywhere in the definition of end; it would cause very strange
     behaviour.

     When the end macro is a roff request or a roff macro, like in

           .ig if

     the subsequent invocation of if will first terminate the ignored text,
     then be invoked as usual.  Otherwise, it only terminates the ignored
     text, and arguments following it or the `..' request are discarded.

   in
     Change indentation.  See man(7).  Ignored in mdoc(7).

   index
     Find a substring in a string.  This is a Heirloom extension and currently
     unsupported.

   it
     Set an input line trap.  Its syntax is as follows:

           .it expression macro

     The named macro will be invoked after processing the number of input text
     lines specified by the numerical expression.  While evaluating the
     expression, the unit suffixes described below Scaling Widths are ignored.

   itc
     Set an input line trap, not counting lines ending with \c.  Currently
     unsupported.

   IX
     To support the generation of a table of contents, pod2man(1) emits this
     user-defined macro, usually without defining it.  To avoid reporting
     large numbers of spurious errors, mandoc(1) ignores it.

   kern
     Switch kerning on or off.  Currently ignored.

   kernafter
     Increase kerning after some characters.  This is a Heirloom extension and
     currently ignored.

   kernbefore
     Increase kerning before some characters.  This is a Heirloom extension
     and currently ignored.

   kernpair
     Add a kerning pair to the kerning table.  This is a Heirloom extension
     and currently ignored.

   lc
     Define a leader repetition character.  Currently unsupported.

   lc_ctype
     Set the LC_CTYPE locale.  This is a Heirloom extension and currently
     unsupported.

   lds
     Define a local string.  This is a Heirloom extension and currently
     unsupported.

   length
     Count the number of input characters in a user-defined string.  Currently
     unsupported.

   letadj
     Dynamic letter spacing and reshaping.  This is a Heirloom extension and
     currently ignored.

   lf
     Change the line number for error messages.  Ignored because insecure.

   lg
     Switch the ligature mechanism on or off.  Currently ignored.

   lhang
     Hang characters at left margin.  This is a Heirloom extension and
     currently ignored.

   linetabs
     Enable or disable line-tabs mode.  This is a groff extension and
     currently unsupported.

   ll
     Change the output line length.  Its syntax is as follows:

           .ll [[+|-]width]

     If the width argument is omitted, the line length is reset to its
     previous value.  The default setting for terminal output is 78n.  If a
     sign is given, the line length is added to or subtracted from; otherwise,
     it is set to the provided value.  Using this request in new manuals is
     discouraged for several reasons, among others because it overrides the
     mandoc(1) -O width command line option.

   lnr
     Set local number register.  This is a Heirloom extension and currently
     unsupported.

   lnrf
     Set local floating-point register.  This is a Heirloom extension and
     currently unsupported.

   lpfx
     Set a line prefix.  This is a Heirloom extension and currently
     unsupported.

   ls
     Set line spacing.  It takes one integer argument specifying the vertical
     distance of subsequent output text lines measured in v units.  Currently
     ignored.

   lsm
     Set a leading spaces trap.  This is a groff extension and currently
     unsupported.

   lt
     Set title line length.  Currently ignored.

   mc
     Print margin character in the right margin.  Currently ignored.

   mediasize
     Set the device media size.  This is a Heirloom extension and currently
     ignored.

   minss
     Set minimum word space.  This is a Heirloom extension and currently
     ignored.

   mk
     Mark vertical position.  Currently ignored.

   mso
     Load a macro file.  Ignored because insecure.

   na
     Disable adjusting without changing the adjustment mode.  Currently
     ignored.

   ne
     Declare the need for the specified minimum vertical space before the next
     trap or the bottom of the page.  Currently ignored.

   nf
     Switch to no-fill mode.  See man(7).  Ignored by mdoc(7).

   nh
     Turn off automatic hyphenation mode.  Currently ignored.

   nhychar
     Define hyphenation-inhibiting characters.  This is a Heirloom extension
     and currently ignored.

   nm
     Print line numbers.  Currently unsupported.

   nn
     Temporarily turn off line numbering.  Currently unsupported.

   nop
     Execute the rest of the input line as a request or macro line.  Currently
     unsupported.

   nr
     Define or change a register.  A register is an arbitrary string value
     that defines some sort of state, which influences parsing and/or
     formatting.  Its syntax is as follows:

           .nr name [+|-]expression

     For the syntax of expression, see Numerical expressions below.  If it is
     prefixed by a sign, the register will be incremented or decremented
     instead of assigned to.

     The following register name is handled specially:

     nS      If set to a positive integer value, certain mdoc(7) macros will
             behave in the same way as in the SYNOPSIS section.  If set to 0,
             these macros will behave in the same way as outside the SYNOPSIS
             section, even when called within the SYNOPSIS section itself.
             Note that starting a new mdoc(7) section with the Sh macro will
             reset this register.

   nrf
     Define or change a floating-point register.  This is a Heirloom extension
     and currently unsupported.

   nroff
     Force nroff mode.  This is a groff extension and currently ignored.

   ns
     Turn on no-space mode.  Currently ignored.

   nx
     Abort processing of the current input file and process another one.
     Ignored because insecure.

   open
     Open a file for writing.  Ignored because insecure.

   opena
     Open a file for appending.  Ignored because insecure.

   os
     Output saved vertical space.  Currently ignored.

   output
     Output directly to intermediate output.  Not supported.

   padj
     Globally control paragraph-at-once adjustment.  This is a Heirloom
     extension and currently ignored.

   papersize
     Set the paper size.  This is a Heirloom extension and currently ignored.

   pc
     Change the page number character.  Currently ignored.

   pev
     Print environments.  This is a groff extension and currently ignored.

   pi
     Pipe output to a shell command.  Ignored because insecure.

   PI
     Low-level request used by BP.  This is a Heirloom extension and currently
     unsupported.

   pl
     Change page length.  Takes one height argument.  Currently ignored.

   pm
     Print names and sizes of macros, strings, and diversions.  Currently
     ignored.

   pn
     Change page number of the next page.  Currently ignored.

   pnr
     Print all number registers.  Currently ignored.

   po
     Set horizontal page offset.  Currently ignored.

   ps
     Change point size.  Takes one numerical argument.  Currently ignored.

   psbb
     Retrieve the bounding box of a PostScript file.  Currently unsupported.

   pshape
     Set a special shape for the current paragraph.  This is a Heirloom
     extension and currently unsupported.

   pso
     Include output of a shell command.  Ignored because insecure.

   ptr
     Print the names and positions of all traps.  This is a groff extension
     and currently ignored.

   pvs
     Change post-vertical spacing.  This is a groff extension and currently
     ignored.

   rchar
     Remove glyph definitions.  Currently unsupported.

   rd
     Read from standard input.  Currently ignored.

   recursionlimit
     Set the maximum stack depth for recursive macros.  This is a Heirloom
     extension and currently ignored.

   return
     Exit a macro and return to the caller.  Currently unsupported.

   rfschar
     Remove font-specific fallback glyph definitions.  Currently unsupported.

   rhang
     Hang characters at right margin.  This is a Heirloom extension and
     currently ignored.

   rj
     Justify unfilled text to the right margin.  Currently ignored.

   rm
     Remove a request, macro or string.  Its syntax is as follows:

           .rm name

   rn
     Rename a request, macro, diversion, or string.  Currently unsupported.

   rnn
     Rename a number register.  Currently unsupported.

   rr
     Remove a register.  Its syntax is as follows:

           .rr name

   rs
     End no-space mode.  Currently ignored.

   rt
     Return to marked vertical position.  Currently ignored.

   schar
     Define global fallback glyph.  This is a groff extension and currently
     unsupported.

   sentchar
     Define sentence-ending characters.  This is a Heirloom extension and
     currently ignored.

   shc
     Change the soft hyphen character.  Currently ignored.

   shift
     Shift macro arguments.  Currently unsupported.

   sizes
     Define permissible point sizes.  This is a groff extension and currently
     ignored.

   so
     Include a source file.  Its syntax is as follows:

           .so file

     The file will be read and its contents processed as input in place of the
     `.so' request line.  To avoid inadvertent inclusion of unrelated files,
     mandoc(1) only accepts relative paths not containing the strings "../"
     and "/..".

     This request requires man(1) to change to the right directory before
     calling mandoc(1), per convention to the root of the manual tree.
     Typical usage looks like:

           .so man3/Xcursor.3

     As the whole concept is rather fragile, the use of so is discouraged.
     Use ln(1) instead.

   spacewidth
     Set the space width from the font metrics file.  This is a Heirloom
     extension and currently ignored.

   special
     Define a special font.  This is a groff extension and currently ignored.

   spreadwarn
     Warn about wide spacing between words.  Currently ignored.

   ss
     Set space character size.  Currently ignored.

   sty
     Associate style with a font position.  This is a groff extension and
     currently ignored.

   substring
     Replace a user-defined string with a substring.  Currently unsupported.

   sv
     Save vertical space.  Currently ignored.

   sy
     Execute shell command.  Ignored because insecure.

   T&
     Re-start a table layout, retaining the options of the prior table
     invocation.  See TS.

   ta
     Set tab stops.  Takes an arbitrary number of arguments.  Currently
     unsupported.

   tc
     Change tab repetition character.  Currently unsupported.

   TE
     End a table context.  See TS.

   ti
     Temporary indent.  Currently unsupported.

   tkf
     Enable track kerning for a font.  Currently ignored.

   tl
     Print a title line.  Currently unsupported.

   tm
     Print to standard error output.  Currently ignored.

   tm1
     Print to standard error output, allowing leading blanks.  This is a groff
     extension and currently ignored.

   tmc
     Print to standard error output without a trailing newline.  This is a
     groff extension and currently ignored.

   tr
     Output character translation.  Its syntax is as follows:

           .tr [ab]+

     Pairs of ab characters are replaced (a for b).  Replacement (or origin)
     characters may also be character escapes; thus,

           tr \(xx\(yy

     replaces all invocations of \(xx with \(yy.

   track
     Static letter space tracking.  This is a Heirloom extension and currently
     ignored.

   transchar
     Define transparent characters for sentence-ending.  This is a Heirloom
     extension and currently ignored.

   trf
     Output the contents of a file, disallowing invalid characters.  This is a
     groff extension and ignored because insecure.

   trimat
     Set the TrimBox page parameter for PDF generation.  This is a Heirloom
     extension and currently ignored.

   trin
     Output character translation, ignored by asciify.  Currently unsupported.

   trnt
     Output character translation, ignored by \!.  Currently unsupported.

   troff
     Force troff mode.  This is a groff extension and currently ignored.

   TS
     Begin a table, which formats input in aligned rows and columns.  See
     tbl(7) for a description of the tbl language.

   uf
     Globally set the underline font.  Currently ignored.

   ul
     Underline.  Currently ignored.

   unformat
     Unformat spaces and tabs in a diversion.  Currently unsupported.

   unwatch
     Disable notification for string or macro.  This is a Heirloom extension
     and currently ignored.

   unwatchn
     Disable notification for register.  This is a Heirloom extension and
     currently ignored.

   vpt
     Enable or disable vertical position traps.  This is a groff extension and
     currently ignored.

   vs
     Change vertical spacing.  Currently ignored.

   warn
     Set warning level.  Currently ignored.

   warnscale
     Set the scaling indicator used in warnings.  This is a groff extension
     and currently ignored.

   watch
     Notify on change of string or macro.  This is a Heirloom extension and
     currently ignored.

   watchlength
     On change, report the contents of macros and strings up to the specified
     length.  This is a Heirloom extension and currently ignored.

   watchn
     Notify on change of register.  This is a Heirloom extension and currently
     ignored.

   wh
     Set a page location trap.  Currently unsupported.

   while
     Repeated execution while a condition is true.  Currently unsupported.

   write
     Write to an open file.  Ignored because insecure.

   writec
     Write to an open file without appending a newline.  Ignored because
     insecure.

   writem
     Write macro or string to an open file.  Ignored because insecure.

   xflag
     Set the extension level.  This is a Heirloom extension and currently
     ignored.

   Numerical expressions
     The nr, if, and ie requests accept integer numerical expressions as
     arguments.  These are always evaluated using the C int type; integer
     overflow works the same way as in the C language.  Numbers consist of an
     arbitrary number of digits `0' to `9' prefixed by an optional sign `+' or
     `-'.  Each number may be followed by one optional scaling unit described
     below Scaling Widths.  The following equations hold:

           1i = 6v = 6P = 10m = 10n = 72p = 1000M = 240u = 240
           254c = 100i = 24000u = 24000
           1f = 65536u = 65536

     The following binary operators are implemented.  Unless otherwise stated,
     they behave as in the C language:

     +   addition
     -   subtraction
     *   multiplication
     /   division
     %   remainder of division
     <   less than
     >   greater than
     ==  equal to
     =   equal to, same effect as == (this differs from C)
     <=  less than or equal to
     >=  greater than or equal to
     <>  not equal to (corresponds to C !=; this one is of limited
         portability, it is supported by Heirloom roff, but not by groff)
     &   logical and (corresponds to C &&)
     :   logical or (corresponds to C ||)
     <?  minimum (not available in C)
     >?  maximum (not available in C)

     There is no concept of precedence; evaluation proceeds from left to
     right, except when subexpressions are enclosed in parantheses.  Inside
     parentheses, whitespace is ignored.

ESCAPE SEQUENCE REFERENCE
     The mandoc(1) roff parser recognises the following escape sequences.
     Note that the roff language defines more escape sequences not implemented
     in mandoc(1).  In mdoc(7) and man(7) documents, using escape sequences is
     discouraged except for those described in the LANGUAGE SYNTAX section
     above.

     A backslash followed by any character not listed here simply prints that
     character itself.

   \<newline>
     A backslash at the end of an input line can be used to continue the
     logical input line on the next physical input line, joining the text on
     both lines together as if it were on a single input line.

   \<space>
     The escape sequence backslash-space (`\ ') is an unpaddable space-sized
     non-breaking space character; see Whitespace.

   \"
     The rest of the input line is treated as Comments.

   \%
     Hyphenation allowed at this point of the word; ignored by mandoc(1).

   \&
     Non-printing zero-width character; see Whitespace.

   \'
     Acute accent special character; use `\(aa' instead.

   \(cc
     Special Characters with two-letter names, see mandoc_char(7).

   \*[name]
     Interpolate the string with the name; see Predefined Strings and ds.  For
     short names, there are variants \*c and \*(cc.

   \,
     Left italic correction (groff extension); ignored by mandoc(1).

   \-
     Special character "mathematical minus sign".

   \/
     Right italic correction (groff extension); ignored by mandoc(1).

   \[name]
     Special Characters with names of arbitrary length, see mandoc_char(7).

   \^
     One-twelfth em half-narrow space character, effectively zero-width in
     mandoc(1).

   \`
     Grave accent special character; use `\(ga' instead.

   \{
     Begin conditional input; see if.

   \|
     One-sixth em narrow space character, effectively zero-width in mandoc(1).

   \}
     End conditional input; see if.

   \~
     Paddable non-breaking space character.

   \0
     Digit width space character.

   \A'string'
     Anchor definition; ignored by mandoc(1).

   \B'string'
     Interpolate `1' if string conforms to the syntax of Numerical expressions
     explained above and `0' otherwise.

   \b'string'
     Bracket building function; ignored by mandoc(1).

   \C'name'
     Special Characters with names of arbitrary length.

   \c
     When encountered at the end of an input text line, the next input text
     line is considered to continue that line, even if there are request or
     macro lines in between.  No whitespace is inserted.

   \D'string'
     Draw graphics function; ignored by mandoc(1).

   \d
     Move down by half a line; ignored by mandoc(1).

   \e
     Backslash special character.

   \F[name]
     Switch font family (groff extension); ignored by mandoc(1).  For short
     names, there are variants \Fc and \F(cc.

   \f[name]
     Switch to the font name, see Text Decoration.  For short names, there are
     variants \fc and \f(cc.

   \g[name]
     Interpolate the format of a number register; ignored by mandoc(1).  For
     short names, there are variants \gc and \g(cc.

   \H'[+|-]number'
     Set the height of the current font; ignored by mandoc(1).

   \h'number'
     Horizontal motion; ignored by mandoc(1).

   \k[name]
     Mark horizontal input place in register; ignored by mandoc(1).  For short
     names, there are variants \kc and \k(cc.

   \L'number[c]'
     Vertical line drawing function; ignored by mandoc(1).

   \l'number[c]'
     Horizontal line drawing function; ignored by mandoc(1).

   \M[name]
     Set fill (background) color (groff extension); ignored by mandoc(1).  For
     short names, there are variants \Mc and \M(cc.

   \m[name]
     Set glyph drawing color (groff extension); ignored by mandoc(1).  For
     short names, there are variants \mc and \m(cc.

   \N'number'
     Character number on the current font.

   \n[name]
     Interpolate the number register name.  For short names, there are
     variants \nc and \n(cc.

   \o'string'
     Overstrike, writing all the characters contained in the string to the
     same output position.  In terminal and HTML output modes, only the last
     one of the characters is visible.

   \R'name [+|-]number'
     Set number register; ignored by mandoc(1).

   \S'number'
     Slant output; ignored by mandoc(1).

   \s'[+|-]number'
     Change point size; ignored by mandoc(1).  Alternative forms \s[+|-]n,
     \s[+|-]'number', \s[[+|-]number], and \s[+|-][number] are also parsed and
     ignored.

   \t
     Horizontal tab; ignored by mandoc(1).

   \u
     Move up by half a line; ignored by mandoc(1).

   \V[name]
     Interpolate an environment variable; ignored by mandoc(1).  For short
     names, there are variants \Vc and \V(cc.

   \v'number'
     Vertical motion; ignored by mandoc(1).

   \w'string'
     Interpolate the width of the string.  The mandoc(1) implementation
     assumes that after expansion of user-defined strings, the string only
     contains normal characters, no escape sequences, and that each character
     has a width of 24 basic units.

   \X'string'
     Output string as device control function; ignored in nroff mode and by
     mandoc(1).

   \x'number'
     Extra line space function; ignored by mandoc(1).

   \Y[name]
     Output a string as a device control function; ignored in nroff mode and
     by mandoc(1).  For short names, there are variants \Yc and \Y(cc.

   \Z'string'
     Print string with zero width and height; ignored by mandoc(1).

   \z
     Output the next character without advancing the cursor position.

COMPATIBILITY
     The mandoc(1) implementation of the roff language is intentionally
     incomplete.  Unimplemented features include:

     -   For security reasons, mandoc(1) never reads or writes external files
         except via so requests with safe relative paths.
     -   There is no automatic hyphenation, no adjustment to the right margin,
         and no centering; the output is always set flush-left.
     -   Support for setting tabulator positions and tabulator and leader
         characters is missing, and support for manually changing indentation
         is limited.
     -   The `u' scaling unit is the default terminal unit.  In traditional
         troff systems, this unit changes depending on the output media.
     -   Width measurements are implemented in a crude way and often yield
         wrong results.  Explicit movement requests and escapes are ignored.
     -   There is no concept of output pages, no support for floats, graphics
         drawing, and picture inclusion; terminal output is always continuous.
     -   Requests regarding color, font families, and glyph manipulation are
         ignored.  Font support is very limited.  Kerning is not implemented,
         and no ligatures are produced.
     -   The "'" macro control character does not suppress output line breaks.
     -   Diversions are not implemented, and support for traps is very
         incomplete.
     -   While recursion is supported, while loops are not.

     The special semantics of the nS number register is an idiosyncracy of
     OpenBSD manuals and not supported by other mdoc(7) implementations.

SEE ALSO
     mandoc(1), eqn(7), man(7), mandoc_char(7), mdoc(7), tbl(7)

     Joseph F. Ossanna and Brian W. Kernighan, Troff User's Manual, AT&T Bell
     Laboratories, Computing Science Technical Report, 54,
     http://www.kohala.com/start/troff/cstr54.ps, Murray Hill, New Jersey,
     1976 and 1992.

     Joseph F. Ossanna, Brian W. Kernighan, and Gunnar Ritter, Heirloom
     Documentation Tools Nroff/Troff User's Manual,
     http://heirloom.sourceforge.net/doctools/troff.pdf, September 17, 2007.

HISTORY
     The RUNOFF typesetting system, whose input forms the basis for roff, was
     written in MAD and FAP for the CTSS operating system by Jerome E.
     Saltzer in 1964.  Doug McIlroy rewrote it in BCPL in 1969, renaming it
     roff.  Dennis M. Ritchie rewrote McIlroy's roff in PDP-11 assembly for
     Version 1 AT&T UNIX, Joseph F. Ossanna improved roff and renamed it nroff
     for Version 2 AT&T UNIX, then ported nroff to C as troff, which Brian W.
     Kernighan released with Version 7 AT&T UNIX.  In 1989, James Clarke re-
     implemented troff in C++, naming it groff.

AUTHORS
     This roff reference was written by Kristaps Dzonsons <kristaps@bsd.lv>
     and Ingo Schwarze <schwarze@openbsd.org>.

NetBSD 8.0                    September 24, 2015                    NetBSD 8.0