Ubuntu Manpage: roff - roff language reference for mandoc

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 bold italic, 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 [message]
Abort processing. Currently unsupported.

ad [b | c | l | n | r]
Set line adjustment mode for subsequent text. Currently ignored.

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

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

als newname oldname
Create an alias for a request, string, macro, or diversion.

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

am1 macroname [endmacro]
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 macrostring [endstring]
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 macrostring [endstring]
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 stringname [string]
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 stringname [string]
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 divname
Fully unformat a diversion. Currently unsupported.

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

bd font [curfont] [offset]
Artificially embolden by repeated printing with small shifts. Currently ignored.

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

blm macroname
Set a blank line trap. Currently unsupported.

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

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

bp [+|-]pagenumber
Begin a new page. Currently ignored.

BP source height width position offset flags label
Define a frame and place a picture in it. This is a Heirloom extension and
currently unsupported.

br Break the output line.

break
Break out of a while loop. Currently unsupported.

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

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

c2 [char]
Change the no-break control character. Currently unsupported.

cc [char]
Change the control character. If char is not specified, the control character is
reset to ‘.’. Trailing characters are ignored.

ce [N] Center the next N input lines without filling. N defaults to 1. An argument of 0
or less ends centering. Currently, high level macros abort centering.

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

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

ch macroname [dist]
Change a trap location. Currently ignored.

char glyphname [string]
Define a new glyph. Currently unsupported.

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

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

close streamname
Close an open file. Ignored because insecure.

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

color [1 | 0]
Activate or deactivate colors. This is a groff extension and currently ignored.

composite from to
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 [1 | 0]
Switch roff compatibility mode on or off. Currently ignored.

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

cs font [width [emsize]]
Constant character spacing mode. Currently ignored.

cu [N] Underline next N input lines including whitespace. Currently ignored.

da divname
Append to a diversion. Currently unsupported.

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

de macroname [endmacro]
Define a roff macro. Its syntax can be either

.de macroname
definition
..

.de macroname endmacro
definition
.endmacro

Both forms define or redefine the macro macroname to represent the 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 endmacro macro works in the same way as for ig; namely, the
call to ‘.endmacro’ first ends the 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

.macroname [argument [argument ...]]

Regarding argument parsing, see MACRO SYNTAX above.

The line invoking the macro will be replaced in the input stream by the
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 macroname clobbers the user-defined string macroname, and the 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 macroname [endmacro]
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 newname scheme component ...
Define a color name. This is a groff extension and currently ignored.

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

.de \*[macrostring] [\*[endstring]]

dei1 macrostring [endstring]
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 string ...

devicem stringname
These two requests only make sense with the groff-specific intermediate output
format and are unsupported.

di divname
Begin a diversion. Currently unsupported.

do command [argument ...]
Execute roff request or macro line with compatibility mode disabled. Currently
unsupported.

ds stringname [["]string]
Define a user-defined string. The stringname 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 \*[stringname] for a
stringname of arbitrary length, or \*(NN or \*N if the length of stringname 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 stringname clobbers the macro stringname, and the stringname 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 stringname [["]string]
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 dist macroname
Set a location trap in the current diversion. This is a Heirloom extension and
currently unsupported.

dt [dist macroname]
Set a trap within a diversion. Currently unsupported.

ec [char]
Enable the escape mechanism and change the escape character. The char argument
defaults to the backslash (‘\’).

ecr Restore the escape character. Currently unsupported.

ecs Save the escape character. Currently unsupported.

el body 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 macroname
Set a trap at the end of input. Currently unsupported.

EN End an equation block. See EQ.

eo Disable the escape mechanism completely.

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

ev [envname]
Switch to another environment. Currently unsupported.

evc [envname]
Copy an environment into the current environment. Currently unsupported.

ex Abort processing and exit. Currently unsupported.

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

fam [familyname]
Change the font family. This is a groff extension and currently ignored.

fc [delimchar [padchar]]
Define a delimiting and a padding character for fields. Currently unsupported.

fchar glyphname [string]
Define a fallback glyph. Currently unsupported.

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

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

feature +|-name
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 font minkern
Control the use of kerning tables for a font. This is a Heirloom extension and
currently ignored.

fl Flush output. Currently ignored.

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

fp position font [filename]
Assign font position. Currently ignored.

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

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

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

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

ft [font]
Change the 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 and may be overridden by macros and escape
sequences.

ftr newname [oldname]
Translate font name. This is a groff extension and currently ignored.

fzoom font [permille]
Zoom font size. Currently ignored.

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

hc [char]
Set the hyphenation character. Currently ignored.

hcode char code ...
Set hyphenation codes of characters. Currently ignored.

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

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

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

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

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

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

hw word ...
Specify hyphenation points in words. Currently ignored.

hy [mode]
Set automatic hyphenation mode. Currently ignored.

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

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

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

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

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

ie condition body
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 condition body
Begin a conditional. This request can also be written as follows:

.if condition \{body
body ...\}

.if condition \{\
body ...
.\}

The condition is a boolean expression. Currently, mandoc(1) supports the
following subset of roff conditionals:

• If ‘!’ is prefixed to condition, it is logically inverted.

• If the first character of condition is ‘n’ (nroff mode) or ‘o’ (odd page), it
evaluates to true.

• If the first character of condition is ‘c’ (character available), ‘e’ (even
page), ‘t’ (troff mode), or ‘v’ (vroff mode), it evaluates to false.

• If the first character of condition is ‘d’, it evaluates to true if the rest
of condition is the name of an existing user defined macro or string;
otherwise, it evaluates to false.

• If the first character of condition is ‘r’, it evaluates to true if the rest
of condition is the name of an existing number register; otherwise, it
evaluates to false.

• If the condition 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 condition is regarded as a delimiter and it
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 condition 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 condition 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 condition \{\
.request
.\}

than having the request or macro follow as

.if condition \{.request

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 [endmacro]
Ignore input. Its syntax can be either

.ig
ignored text
..

.ig endmacro
ignored text
.endmacro

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 ‘.endmacro’ is
encountered. Do not use the escape character ‘\’ anywhere in the definition of
endmacro; it would cause very strange behaviour.

When the endmacro 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 [[+|-]width]
Change indentation. See man(7). Ignored in mdoc(7).

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

it expression macro
Set an input line trap. 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.

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

IX class keystring
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 [1 | 0]
Switch kerning on or off. Currently ignored.

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

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

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

lc [glyph]
Define a leader repetition character. Currently unsupported.

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

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

length register string
Count the number of input characters in a string. Currently unsupported.

letadj lspmin lshmin letss lspmax lshmax
Dynamic letter spacing and reshaping. This is a Heirloom extension and currently
ignored.

lf lineno [filename]
Change the line number for error messages. Ignored because insecure.

lg [1 | 0]
Switch the ligature mechanism on or off. Currently ignored.

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

linetabs [1 | 0]
Enable or disable line-tabs mode. This is a groff extension and currently
unsupported.

ll [[+|-]width]
Change the output line length. 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 register [+|-]value [increment]
Set local number register. This is a Heirloom extension and currently
unsupported.

lnrf register [+|-]value [increment]
Set local floating-point register. This is a Heirloom extension and currently
unsupported.

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

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

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

lt [[+|-]width]
Set title line length. Currently ignored.

mc glyph [dist]
Print margin character in the right margin. The dist is currently ignored;
instead, 1n is used.

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

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

mk [register]
Mark vertical position. Currently ignored.

mso filename
Load a macro file using the search path. Ignored because insecure.

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

ne [height]
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 char ...
Define hyphenation-inhibiting characters. This is a Heirloom extension and
currently ignored.

nm [start [inc [space [indent]]]]
Print line numbers. Currently unsupported.

nn [number]
Temporarily turn off line numbering. Currently unsupported.

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

nr register [+|-]expression
Define or change a register. A register is an arbitrary string value that defines
some sort of state, which influences parsing and/or formatting. 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 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 register [+|-]expression
[increment] 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 [filename]
Abort processing of the current input file and process another one. Ignored
because insecure.

open stream file
Open a file for writing. Ignored because insecure.

opena stream file
Open a file for appending. Ignored because insecure.

os Output saved vertical space. Currently ignored.

output string
Output directly to intermediate output. Not supported.

padj [1 | 0]
Globally control paragraph-at-once adjustment. This is a Heirloom extension and
currently ignored.

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

pc [char]
Change the page number character. Currently ignored.

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

pi command
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 [[+|-]height]
Change page length. Currently ignored.

pm Print names and sizes of macros, strings, and diversions to standard error output.
Currently ignored.

pn [+|-]number
Change the page number of the next page. Currently ignored.

pnr Print all number registers on standard error output. Currently ignored.

po [[+|-]offset]
Set a horizontal page offset. If no argument is specified, the page offset is
reverted to its previous value. If a sign is specified, the new page offset is
calculated relative to the current one; otherwise, it is absolute. The argument
follows the syntax of Scaling Widths and the default scaling unit is m.

ps [[+|-]size]
Change point size. Currently ignored.

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

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

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

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

pvs [[+|-]height]
Change post-vertical spacing. This is a groff extension and currently ignored.

rchar glyph ...
Remove glyph definitions. Currently unsupported.

rd [prompt [agument ...]]
Read from standard input. Currently ignored.

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

return [twice]
Exit a macro and return to the caller. Currently unsupported.

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

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

rj [N] Justify the next N input lines to the right margin without filling. N defaults to
1. An argument of 0 or less ends right adjustment.

rm macroname
Remove a request, macro or string.

rn oldname newname
Rename a request, macro, diversion, or string. In mandoc(1), user-defined macros,
mdoc(7) and man(7) macros, and user-defined strings can be renamed, but renaming
of predefined strings and of roff requests is not supported, and diversions are
not implemented at all.

rnn oldname newname
Rename a number register. Currently unsupported.

rr register
Remove a register.

rs End no-space mode. Currently ignored.

rt [dist]
Return to marked vertical position. Currently ignored.

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

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

shc [glyph]
Change the soft hyphen character. Currently ignored.

shift [number]
Shift macro arguments. Currently unsupported.

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

so filename
Include a source file. The file is 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.

sp [height]
Break the output line and emit vertical space. The argument follows the syntax of
Scaling Widths and defaults to one blank line (1v).

spacewidth [1 | 0]
Set the space width from the font metrics file. This is a Heirloom extension and
currently ignored.

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

spreadwarn [width]
Warn about wide spacing between words. Currently ignored.

ss wordspace [sentencespace]
Set space character size. Currently ignored.

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

substring stringname startpos [endpos]
Replace a user-defined string with a substring. Currently unsupported.

sv [height]
Save vertical space. Currently ignored.

sy command
Execute shell command. Ignored because insecure.

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

ta [width ... [T width ...]]
Set tab stops. Each width argument follows the syntax of Scaling Widths. If
prefixed by a plus sign, it is relative to the previous tab stop. The arguments
after the T marker are used repeatedly as often as needed; for each reuse, they
are taken relative to the last previously established tab stop. When ta is called
without arguments, all tab stops are cleared.

tc [glyph]
Change tab repetition character. Currently unsupported.

TE End a table context. See TS.

ti [+|-]width
Break the output line and indent the next output line by width. If a sign is
specified, the temporary indentation is calculated relative to the current
indentation; otherwise, it is absolute. The argument follows the syntax of
Scaling Widths and the default scaling unit is m.

tkf font minps width1 maxps width2
Enable track kerning for a font. Currently ignored.

tl 'left'center'right'Print a title line.
Currently unsupported.

tm string
Print to standard error output. Currently ignored.

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

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

tr glyph glyph ...
Output character translation. The first glyph in each pair is replaced by the
second one. Character escapes can be used; for example,

tr \(xx\(yy

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

track font minps width1 maxps width2
Static letter space tracking. This is a Heirloom extension and currently ignored.

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

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

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

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

trnt glyph glyph ...
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 font Globally set the underline font. Currently ignored.

ul [N] Underline next N input lines. Currently ignored.

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

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

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

vpt [1 | 0]
Enable or disable vertical position traps. This is a groff extension and
currently ignored.

vs [[+|-]height]
Change vertical spacing. Currently ignored.

warn flags
Set warning level. Currently ignored.

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

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

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

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

wh dist [macroname]
Set a page location trap. Currently unsupported.

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

write ["]string
Write to an open file. Ignored because insecure.

writec ["]string
Write to an open file without appending a newline. Ignored because insecure.

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

xflag level
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 parentheses. 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'[|]width'
       Horizontal motion.  If the vertical bar is given, the motion is relative to the current
       indentation.  Otherwise, it is relative to the current position.  The default scaling unit
       is m.

   \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'width[c]'
       Draw a horizontal line of width using the glyph c.

   \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.

   \p
       Break the output line at the end of the current word.

   \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.

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>.