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MDOC(7)		   FreeBSD Miscellaneous Information Manual	       MDOC(7)

     mdoc -- semantic markup language for formatting manual pages

     The mdoc language supports	authoring of manual pages for the man(1) util-
     ity by allowing semantic annotations of words, phrases, page sections and
     complete manual pages.  Such annotations are used by formatting tools to
     achieve a uniform presentation across all manuals written in mdoc,	and to
     support hyperlinking if supported by the output medium.

     This reference document describes the structure of	manual pages and the
     syntax and	usage of the mdoc language.  The reference implementation of a
     parsing and formatting tool is mandoc(1); the COMPATIBILITY section
     describes compatibility with other	implementations.

     In	an mdoc	document, lines	beginning with the control character `.' are
     called ``macro lines''.  The first	word is	the macro name.	 It consists
     of	two or three letters.  Most macro names	begin with a capital letter.
     For a list	of available macros, see MACRO OVERVIEW.  The words following
     the macro name are	arguments to the macro,	optionally including the names
     of	other, callable	macros;	see MACRO SYNTAX for details.

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

	   .Sh Macro lines change control state.
	   Text	lines are interpreted within the current state.

     Many aspects of the basic syntax of the mdoc language are based on	the
     roff(7) language; see the LANGUAGE	SYNTAX and MACRO SYNTAX	sections in
     the roff(7) manual	for details, in	particular regarding comments, escape
     sequences,	whitespace, and	quoting.  However, using roff(7) requests in
     mdoc documents is discouraged; mandoc(1) supports some of them merely for
     backward compatibility.

     A well-formed mdoc	document consists of a document	prologue followed by
     one or more sections.

     The prologue, which consists of the Dd, Dt, and Os	macros in that order,
     is	required for every document.

     The first section (sections are denoted by	Sh) must be the	NAME section,
     consisting	of at least one	Nm followed by Nd.

     Following that, convention	dictates specifying at least the SYNOPSIS and
     DESCRIPTION sections, although this varies	between	manual sections.

     The following is a	well-formed skeleton mdoc file for a utility

	   .Dd $Mdocdate$
	   .Dt PROGNAME	section
	   .Sh NAME
	   .Nm progname
	   .Nd one line	about what it does
	   .\" .Sh LIBRARY
	   .\" For sections 2, 3, and 9	only.
	   .\" Not used	in OpenBSD.
	   .Nm progname
	   .Op Fl options
	   utility processes files ...
	   .\" .Sh CONTEXT
	   .\" For section 9 functions only.
	   .\" Not used	in OpenBSD.
	   .\" For sections 2, 3, and 9	function return	values only.
	   .\" For sections 1, 6, 7, and 8 only.
	   .\" .Sh FILES
	   .\" .Sh EXIT	STATUS
	   .\" For sections 1, 6, and 8	only.
	   .\" .Sh EXAMPLES
	   .\" For sections 1, 4, 6, 7,	8, and 9 printf/stderr messages	only.
	   .\" .Sh ERRORS
	   .\" For sections 2, 3, 4, and 9 errno settings only.
	   .\" .Sh SEE ALSO
	   .\" .Xr foobar 1
	   .\" .Sh STANDARDS
	   .\" .Sh HISTORY
	   .\" .Sh AUTHORS
	   .\" .Sh CAVEATS
	   .\" .Sh BUGS
	   .\" Not used	in OpenBSD.

     The sections in an	mdoc document are conventionally ordered as they
     appear above.  Sections should be composed	as follows:

	   The name(s) and a one line description of the documented material.
	   The syntax for this as follows:

		 .Nm name0 ,
		 .Nm name1 ,
		 .Nm name2
		 .Nd a one line	description

	   Multiple `Nm' names should be separated by commas.

	   The Nm macro(s) must	precede	the Nd macro.

	   See Nm and Nd.

	   The name of the library containing the documented material, which
	   is assumed to be a function in a section 2, 3, or 9 manual.	The
	   syntax for this is as follows:

		 .Lb libarm

	   See Lb.

	   Documents the utility invocation syntax, function call syntax, or
	   device configuration.

	   For the first, utilities (sections 1, 6, and	8), this is generally
	   structured as follows:

		 .Nm bar
		 .Op Fl	v
		 .Op Fl	o Ar file
		 .Op Ar
		 .Nm foo
		 .Op Fl	v
		 .Op Fl	o Ar file
		 .Op Ar

	   Commands should be ordered alphabetically.

	   For the second, function calls (sections 2, 3, 9):

		 .In header.h
		 .Vt extern const char *global;
		 .Ft "char *"
		 .Fn foo "const	char *src"
		 .Ft "char *"
		 .Fn bar "const	char *src"

	   Ordering of In, Vt, Fn, and Fo macros should	follow C header-file

	   And for the third, configurations (section 4):

		 .Cd "it* at isa? port 0x2e"
		 .Cd "it* at isa? port 0x4e"

	   Manuals not in these	sections generally don't need a	SYNOPSIS.

	   Some	macros are displayed differently in the	SYNOPSIS section, par-
	   ticularly Nm, Cd, Fd, Fn, Fo, In, Vt, and Ft.  All of these macros
	   are output on their own line.  If two such dissimilar macros	are
	   pairwise invoked (except for	Ft before Fo or	Fn), they are sepa-
	   rated by a vertical space, unless in	the case of Fo,	Fn, and	Ft,
	   which are always separated by vertical space.

	   When	text and macros	following an Nm	macro starting an input	line
	   span	multiple output	lines, all output lines	but the	first will be
	   indented to align with the text immediately following the Nm	macro,
	   up to the next Nm, Sh, or Ss	macro or the end of an enclosing
	   block, whichever comes first.

	   This	begins with an expansion of the	brief, one line	description in

		 utility does this, that, and the other.

	   It usually follows with a breakdown of the options (if documenting
	   a command), such as:

		 The arguments are as follows:
		 .Bl -tag -width Ds
		 .It Fl	v
		 Print verbose information.

	   List	the options in alphabetical order, uppercase before lowercase
	   for each letter and with no regard to whether an option takes an
	   argument.  Put digits in ascending order before all letter options.

	   Manuals not documenting a command won't include the above fragment.

	   Since the DESCRIPTION section usually contains most of the text of
	   a manual, longer manuals often use the Ss macro to form subsec-
	   tions.  In very long	manuals, the DESCRIPTION may be	split into
	   multiple sections, each started by an Sh macro followed by a	non-
	   standard section name, and each having several subsections, like in
	   the present mdoc manual.

	   This	section	lists the contexts in which functions can be called in
	   section 9.  The contexts are	autoconf, process, or interrupt.

	   Implementation-specific notes should	be kept	here.  This is useful
	   when	implementing standard functions	that may have side effects or
	   notable algorithmic implications.

	   This	section	documents the return values of functions in sections
	   2, 3, and 9.

	   See Rv.

	   Lists the environment variables used	by the utility,	and explains
	   the syntax and semantics of their values.  The environ(7) manual
	   provides examples of	typical	content	and formatting.

	   See Ev.

	   Documents files used.  It's helpful to document both	the file name
	   and a short description of how the file is used (created, modified,

	   See Pa.

	   This	section	documents the command exit status for section 1, 6,
	   and 8 utilities.  Historically, this	information was	described in
	   DIAGNOSTICS,	a practise that	is now discouraged.

	   See Ex.

	   Example usages.  This often contains	snippets of well-formed, well-
	   tested invocations.	Make sure that examples	work properly!

	   Documents error messages.  In section 4 and 9 manuals, these	are
	   usually messages printed by the kernel to the console and to	the
	   kernel log.	In section 1, 6, 7, and	8, these are usually messages
	   printed by userland programs	to the standard	error output.

	   Historically, this section was used in place	of EXIT	STATUS for
	   manuals in sections 1, 6, and 8; however, this practise is discour-

	   See Bl -diag.

	   Documents errno(2) settings in sections 2, 3, 4, and	9.

	   See Er.

	   References other manuals with related topics.  This section should
	   exist for most manuals.  Cross-references should conventionally be
	   ordered first by section, then alphabetically (ignoring case).

	   References to other documentation concerning	the topic of the man-
	   ual page, for example authoritative books or	journal	articles, may
	   also	be provided in this section.

	   See Rs and Xr.

	   References any standards implemented	or used.  If not adhering to
	   any standards, the HISTORY section should be	used instead.

	   See St.

	   A brief history of the subject, including where it was first	imple-
	   mented, and when it was ported to or	reimplemented for the operat-
	   ing system at hand.

	   Credits to the person or persons who	wrote the code and/or documen-
	   tation.  Authors should generally be	noted by both name and email

	   See An.

	   Common misuses and misunderstandings	should be explained in this

	   Known bugs, limitations, and	work-arounds should be described in
	   this	section.

	   Documents any security precautions that operators should consider.

     This overview is sorted such that macros of similar purpose are listed
     together, to help find the	best macro for any given purpose.  Deprecated
     macros are	not included in	the overview, but can be found below in	the
     alphabetical MACRO	REFERENCE.

   Document preamble and NAME section macros
     Dd		      document date: $Mdocdate$	| month	day, year
     Dt		      document title: TITLE section [arch]
     Os		      operating	system version:	[system	[version]]
     Nm		      document name (one argument)
     Nd		      document description (one	line)

   Sections and	cross references
     Sh		      section header (one line)
     Ss		      subsection header	(one line)
     Sx		      internal cross reference to a section or subsection
     Xr		      cross reference to another manual	page: name section
     Pp, Lp	      start a text paragraph (no arguments)

   Displays and	lists
     Bd, Ed	      display block: -type [-offset width] [-compact]
     D1		      indented display (one line)
     Dl		      indented literal display (one line)
     Ql		      in-line literal display: `text'
     Bl, El	      list block: -type	[-width	val] [-offset val] [-compact]
     It		      list item	(syntax	depends	on -type)
     Ta		      table cell separator in Bl -column lists
     Rs, %*, Re	      bibliographic block (references)

   Spacing control
     Pf		      prefix, no following horizontal space (one argument)
     Ns		      roman font, no preceding horizontal space	(no arguments)
     Ap		      apostrophe without surrounding whitespace	(no arguments)
     Sm		      switch horizontal	spacing	mode: [on | off]
     Bk, Ek	      keep block: -words

   Semantic markup for command line utilities
     Nm		      start a SYNOPSIS block with the name of a	utility
     Fl		      command line options (flags) (>=0	arguments)
     Cm		      command modifier (>0 arguments)
     Ar		      command arguments	(>=0 arguments)
     Op, Oo, Oc	      optional syntax elements (enclosure)
     Ic		      internal or interactive command (>0 arguments)
     Ev		      environmental variable (>0 arguments)
     Pa		      file system path (>=0 arguments)

   Semantic markup for function	libraries
     Lb		      function library (one argument)
     In		      include file (one	argument)
     Fd		      other preprocessor directive (>0 arguments)
     Ft		      function type (>0	arguments)
     Fo, Fc	      function block: funcname
     Fn		      function name: [functype]	funcname [[argtype] argname]
     Fa		      function argument	(>0 arguments)
     Vt		      variable type (>0	arguments)
     Va		      variable name (>0	arguments)
     Dv		      defined variable or preprocessor constant	(>0 arguments)
     Er		      error constant (>0 arguments)
     Ev		      environmental variable (>0 arguments)

   Various semantic markup
     An		      author name (>0 arguments)
     Lk		      hyperlink: uri [name]
     Mt		      ``mailto'' hyperlink: address
     Cd		      kernel configuration declaration (>0 arguments)
     Ad		      memory address (>0 arguments)
     Ms		      mathematical symbol (>0 arguments)

   Physical markup
     Em		      italic font or underline (emphasis) (>0 arguments)
     Sy		      boldface font (symbolic) (>0 arguments)
     Li		      typewriter font (literal)	(>0 arguments)
     No		      return to	roman font (normal) (no	arguments)
     Bf, Ef	      font block: [-type | Em |	Li | Sy]

   Physical enclosures
     Dq, Do, Dc	      enclose in typographic double quotes: ``text''
     Qq, Qo, Qc	      enclose in typewriter double quotes: "text"
     Sq, So, Sc	      enclose in single	quotes:	`text'
     Pq, Po, Pc	      enclose in parentheses: (text)
     Bq, Bo, Bc	      enclose in square	brackets: [text]
     Brq, Bro, Brc    enclose in curly braces: {text}
     Aq, Ao, Ac	      enclose in angle brackets: <text>
     Eo, Ec	      generic enclosure

   Text	production
     Ex	-std	      standard command exit values: [utility ...]
     Rv	-std	      standard function	return values: [function ...]
     St		      reference	to a standards document	(one argument)
     At		      AT&T UNIX
     Bx		      BSD
     Bsx	      BSD/OS
     Nx		      NetBSD
     Fx		      FreeBSD
     Ox		      OpenBSD
     Dx		      DragonFly

     This section is a canonical reference of all macros, arranged alphabeti-
     cally.  For the scoping of	individual macros, see MACRO SYNTAX.

     Author name of an Rs block.  Multiple authors should each be accorded
     their own %A line.	 Author	names should be	ordered	with full or abbrevi-
     ated forename(s) first, then full surname.

     Book title	of an Rs block.	 This macro may	also be	used in	a non-biblio-
     graphic context when referring to book titles.

     Publication city or location of an	Rs block.

     Publication date of an Rs block.  Recommended formats of arguments	are
     month day,	year or	just year.

     Publisher or issuer name of an Rs block.

     Journal name of an	Rs block.

     Issue number (usually for journals) of an Rs block.

     Optional information of an	Rs block.

     Book or journal page number of an Rs block.

     Institutional author (school, government, etc.) of	an Rs block.  Multiple
     institutional authors should each be accorded their own %Q	line.

     Technical report name of an Rs block.

     Article title of an Rs block.  This macro may also	be used	in a non-bib-
     liographical context when referring to article titles.

     URI of reference document.

     Volume number of an Rs block.

     Close an Ao block.	 Does not have any tail	arguments.

     Memory address.  Do not use this for postal addresses.

	   .Ad [0,$]
	   .Ad 0x00000000

     Author name.  Can be used both for	the authors of the program, function,
     or	driver documented in the manual, or for	the authors of the manual
     itself.  Requires either the name of an author or one of the following

	   -split     Start a new output line before each subsequent invoca-
		      tion of An.
	   -nosplit   The opposite of -split.

     The default is -nosplit.  The effect of selecting either of the -split
     modes ends	at the beginning of the	AUTHORS	section.  In the AUTHORS sec-
     tion, the default is -nosplit for the first author	listing	and -split for
     all other author listings.

	   .An -nosplit
	   .An Kristaps	Dzonsons Aq Mt

     Begin a block enclosed by angle brackets.	Does not have any head argu-

	   .Fl -key= Ns	Ao Ar val Ac

     See also Aq.

     Inserts an	apostrophe without any surrounding whitespace.	This is	gener-
     ally used as a grammatical	device when referring to the verb form of a

	   .Fn execve Ap d

     Encloses its arguments in angle brackets.

	   .Fl -key= Ns	Aq Ar val

     Remarks: this macro is often abused for rendering URIs, which should
     instead use Lk or Mt, or to note pre-processor ``#include'' statements,
     which should use In.

     See also Ao.

     Command arguments.	 If an argument	is not provided, the string ``file
     ...'' is used as a	default.

	   .Fl o Ar file
	   .Ar arg1 , arg2 .

     The arguments to the Ar macro are names and placeholders for command
     arguments;	for fixed strings to be	passed verbatim	as arguments, use Fl
     or	Cm.

     Formats an	AT&T UNIX version.  Accepts one	optional argument:

	   v[1-7] | 32v	  A version of AT&T UNIX.
	   V | V.[1-4]	  A version of AT&T System V UNIX.

     Note that these arguments do not begin with a hyphen.

	   .At III
	   .At V.1

     See also Bsx, Bx, Dx, Fx, Nx, and Ox.

     Close a Bo	block.	Does not have any tail arguments.

     Begin a display block.  Its syntax	is as follows:

	   .Bd -type [-offset width] [-compact]

     Display blocks are	used to	select a different indentation and justifica-
     tion than the one used by the surrounding text.  They may contain both
     macro lines and text lines.  By default, a	display	block is preceded by a
     vertical space.

     The type must be one of the following:

	   -centered	  Produce one output line from each input line,	and
			  center-justify each line.  Using this	display	type
			  is not recommended; many mdoc	implementations	render
			  it poorly.

	   -filled	  Change the positions of line breaks to fill each
			  line,	and left- and right-justify the	resulting

	   -literal	  Produce one output line from each input line,	and do
			  not justify the block	at all.	 Preserve white	space
			  as it	appears	in the input.  Always use a constant-
			  width	font.  Use this	for displaying source code.

	   -ragged	  Change the positions of line breaks to fill each
			  line,	and left-justify the resulting block.

	   -unfilled	  The same as -literal,	but using the same font	as for
			  normal text, which is	a variable width font if sup-
			  ported by the	output device.

     The type must be provided first.  Additional arguments may	follow:

	   -offset width  Indent the display by	the width, which may be	one of
			  the following:

			  One of the pre-defined strings indent, the width of
			  a standard indentation (six constant width charac-
			  ters); indent-two, twice indent; left, which has no
			  effect; right, which justifies to the	right margin;
			  or center, which aligns around an imagined center

			  A macro invocation, which selects a predefined width
			  associated with that macro.  The most	popular	is the
			  imaginary macro Ds, which resolves to	6n.

			  A scaling width as described in roff(7).

			  An arbitrary string, which indents by	the length of
			  this string.

			  When the argument is missing,	-offset	is ignored.

	   -compact	  Do not assert	vertical space before the display.


	   .Bd -literal	-offset	indent -compact
	      Hello	  world.

     See also D1 and Dl.

     Change the	font mode for a	scoped block of	text.  Its syntax is as	fol-

	   .Bf [-emphasis | -literal | -symbolic | Em |	Li | Sy]

     The -emphasis and Em argument are equivalent, as are -symbolic and	Sy,
     and -literal and Li.  Without an argument,	this macro does	nothing.  The
     font mode continues until broken by a new font mode in a nested scope or
     Ef	is encountered.

     See also Li, Ef, Em, and Sy.

     For each macro, keep its output together on the same output line, until
     the end of	the macro or the end of	the input line is reached, whichever
     comes first.  Line	breaks in text lines are unaffected.  The syntax is as

	   .Bk -words

     The -words	argument is required; additional arguments are ignored.

     The following example will	not break within each Op macro line:

	   .Bk -words
	   .Op Fl f Ar flags
	   .Op Fl o Ar output

     Be	careful	in using over-long lines within	a keep block!  Doing so	will
     clobber the right margin.

     Begin a list.  Lists consist of items specified using the It macro, con-
     taining a head or a body or both.	The list syntax	is as follows:

	   .Bl -type [-width val] [-offset val]	[-compact] [HEAD ...]

     The list type is mandatory	and must be specified first.  The -width and
     -offset arguments accept macro names as described for Bd -offset, scaling
     widths as described in roff(7), or	use the	length of the given string.
     The -offset is a global indentation for the whole list, affecting both
     item heads	and bodies.  For those list types supporting it, the -width
     argument requests an additional indentation of item bodies, to be added
     to	the -offset.  Unless the -compact argument is specified, list entries
     are separated by vertical space.

     A list must specify one of	the following list types:

	   -bullet	 No item heads can be specified, but a bullet will be
			 printed at the	head of	each item.  Item bodies	start
			 on the	same output line as the	bullet and are
			 indented according to the -width argument.

	   -column	 A columnated list.  The -width	argument has no
			 effect; instead, the string length of each argument
			 specifies the width of	one column.  If	the first line
			 of the	body of	a -column list is not an It macro
			 line, It contexts spanning one	input line each	are
			 implied until an It macro line	is encountered,	at
			 which point items start being interpreted as
			 described in the It documentation.

	   -dash	 Like -bullet, except that dashes are used in place of

	   -diag	 Like -inset, except that item heads are not parsed
			 for macro invocations.	 Most often used in the
			 DIAGNOSTICS section with error	constants in the item

	   -enum	 A numbered list.  No item heads can be	specified.
			 Formatted like	-bullet, except	that cardinal numbers
			 are used in place of bullets, starting	at 1.

	   -hang	 Like -tag, except that	the first lines	of item	bodies
			 are not indented, but follow the item heads like in
			 -inset	lists.

	   -hyphen	 Synonym for -dash.

	   -inset	 Item bodies follow items heads	on the same line,
			 using normal inter-word spacing.  Bodies are not
			 indented, and the -width argument is ignored.

	   -item	 No item heads can be specified, and none are printed.
			 Bodies	are not	indented, and the -width argument is

	   -ohang	 Item bodies start on the line following item heads
			 and are not indented.	The -width argument is

	   -tag		 Item bodies are indented according to the -width
			 argument.  When an item head fits inside the indenta-
			 tion, the item	body follows this head on the same
			 output	line.  Otherwise, the body starts on the out-
			 put line following the	head.

     Lists may be nested within	lists and displays.  Nesting of	-column	and
     -enum lists may not be portable.

     See also El and It.

     Begin a block enclosed by square brackets.	 Does not have any head	argu-

	   .Bo 1 ,
	   .Dv BUFSIZ Bc

     See also Bq.

     Encloses its arguments in square brackets.

	   .Bq 1, Dv BUFSIZ

     Remarks: this macro is sometimes abused to	emulate	optional arguments for
     commands; the correct macros to use for this purpose are Op, Oo, and Oc.

     See also Bo.

     Close a Bro block.	 Does not have any tail	arguments.

     Begin a block enclosed by curly braces.  Does not have any	head argu-

	   .Bro	1 , ...	,
	   .Va n Brc

     See also Brq.

     Encloses its arguments in curly braces.

	   .Brq	1, ...,	Va n

     See also Bro.

     Format the	BSD/OS version provided	as an argument,	or a default value if
     no	argument is provided.

	   .Bsx	1.0

     See also At, Bx, Dx, Fx, Nx, and Ox.

     Supported only for	compatibility, do not use this in new manuals.	Prints
     ``is currently in beta test.''

     Format the	BSD version provided as	an argument, or	a default value	if no
     argument is provided.

	   .Bx 4.3 Tahoe
	   .Bx 4.4

     See also At, Bsx, Dx, Fx, Nx, and Ox.

     Kernel configuration declaration.	This denotes strings accepted by
     config(8).	 It is most often used in section 4 manual pages.

	   .Cd device le0 at scode?

     Remarks: this macro is commonly abused by using quoted literals to	retain
     whitespace	and align consecutive Cd declarations.	This practise is dis-

     Command modifiers.	 Typically used	for fixed strings passed as arguments,
     unless Fl is more appropriate.  Also useful when specifying configuration
     options or	keys.

	   .Nm mt Fl f Ar device Cm rewind
	   .Nm ps Fl o Cm pid ,	Ns Cm command
	   .Nm dd Cm if= Ns Ar file1 Cm	of= Ns Ar file2
	   .Cm IdentityFile Pa ~/.ssh/id_rsa
	   .Cm LogLevel	Dv DEBUG

     One-line indented display.	 This is formatted by the default rules	and is
     useful for	simple indented	statements.  It	is followed by a newline.

	   .D1 Fl abcdefgh

     See also Bd and Dl.

     This macro	is obsolete.  No replacement is	needed.	 It is ignored by
     mandoc(1) and groff including its arguments.  It was formerly used	to
     toggle a debugging	mode.

     Close a Do	block.	Does not have any tail arguments.

     Document date for display in the page footer.  This is the	mandatory
     first macro of any	mdoc manual.  Its syntax is as follows:

	   .Dd month day, year

     The month is the full English month name, the day is an optionally	zero-
     padded numeral, and the year is the full four-digit year.

     Other arguments are not portable; the mandoc(1) utility handles them as
	-   To have the	date automatically filled in by	the OpenBSD version of
	    cvs(1), the	special	string ``$Mdocdate$'' can be given as an argu-
	-   The	traditional, purely numeric man(7) format year-month-day is
	    accepted, too.
	-   If a date string cannot be parsed, it is used verbatim.
	-   If no date string is given,	the current date is used.

	   .Dd $Mdocdate$
	   .Dd $Mdocdate: July 21 2007$
	   .Dd July 21,	2007

     See also Dt and Os.

     One-line indented display.	 This is formatted as literal text and is use-
     ful for commands and invocations.	It is followed by a newline.

	   .Dl % mandoc	mdoc.7 \(ba less

     See also Ql, Bd -literal, and D1.

     Begin a block enclosed by double quotes.  Does not	have any head argu-

	   April is the	cruellest month
	   \(em	T.S. Eliot

     See also Dq.

     Encloses its arguments in ``typographic'' double-quotes.

	   .Dq April is	the cruellest month
	   \(em	T.S. Eliot

     See also Qq, Sq, and Do.

     Document title for	display	in the page header.  This is the mandatory
     second macro of any mdoc file.  Its syntax	is as follows:

	   .Dt TITLE section [arch]

     Its arguments are as follows:

       TITLE	The document's title (name), defaulting	to ``UNTITLED''	if
		unspecified.  To achieve a uniform appearance of page header
		lines, it should by convention be all caps.

       section	The manual section.  This may be one of	1 (General Commands),
		2 (System Calls), 3 (Library Functions), 3p (Perl Library), 4
		(Device	Drivers), 5 (File Formats), 6 (Games), 7
		(Miscellaneous Information), 8 (System Manager's Manual), or 9
		(Kernel	Developer's Manual).  It should	correspond to the man-
		ual's filename suffix and defaults to the empty	string if

       arch	This specifies the machine architecture	a manual page applies
		to, where relevant, for	example	alpha, amd64, i386, or
		sparc64.  The list of valid architectures varies by operating

	   .Dt FOO 1
	   .Dt FOO 9 i386

     See also Dd and Os.

     Defined variables such as preprocessor constants, constant	symbols, enu-
     meration values, and so on.

	   .Dv NULL
	   .Dv BUFSIZ

     See also Er and Ev	for special-purpose constants, Va for variable sym-
     bols, and Fd for listing preprocessor variable definitions	in the

     Format the	DragonFly version provided as an argument, or a	default	value
     if	no argument is provided.

	   .Dx 2.4.1

     See also At, Bsx, Bx, Fx, Nx, and Ox.

     Close a scope started by Eo.  Its syntax is as follows:

	   .Ec [TERM]

     The TERM argument is used as the enclosure	tail, for example, specifying
     \(rq will emulate Dc.

     End a display context started by Bd.

     End a font	mode context started by	Bf.

     End a keep	context	started	by Bk.

     End a list	context	started	by Bl.

     See also Bl and It.

     Request an	italic font.  If the output device does	not provide that,

     This is most often	used for stress	emphasis (not to be confused with
     importance, see Sy).  In the rare cases where none	of the semantic	markup
     macros fit, it can	also be	used for technical terms and placeholders,
     except that for syntax elements, Sy and Ar	are preferred, respectively.

	   Selected lines are those
	   .Em not
	   matching any	of the specified patterns.
	   Some	of the functions use a
	   .Em hold space
	   to save the pattern space for subsequent retrieval.

     See also Bf, Li, No, and Sy.

     This macro	is obsolete.  Use Eo or	any of the other enclosure macros.

     It	encloses its argument in the delimiters	specified by the last Es

     An	arbitrary enclosure.  Its syntax is as follows:

	   .Eo [TERM]

     The TERM argument is used as the enclosure	head, for example, specifying
     \(lq will emulate Do.

     Error constants for definitions of	the errno libc global variable.	 This
     is	most often used	in section 2 and 3 manual pages.

	   .Er EPERM
	   .Er ENOENT

     See also Dv for general constants.

     This macro	is obsolete.  Use Eo or	any of the other enclosure macros.

     It	takes two arguments, defining the delimiters to	be used	by subsequent
     En	macros.

     Environmental variables such as those specified in	environ(7).

	   .Ev PATH

     See also Dv for general constants.

     Insert a standard sentence	regarding command exit values of 0 on success
     and >0 on failure.	 This is most often used in section 1, 6, and 8	manual
     pages.  Its syntax	is as follows:

	   .Ex -std [utility ...]

     If	utility	is not specified, the document's name set by Nm	is used.  Mul-
     tiple utility arguments are treated as separate utilities.

     See also Rv.

     Function argument or parameter.  Its syntax is as follows:

	   .Fa "[argtype] [argname]" ...

     Each argument may be a name and a type (recommended for the SYNOPSIS sec-
     tion), a name alone (for function invocations), or	a type alone (for
     function prototypes).  If both a type and a name are given	or if the type
     consists of multiple words, all words belonging to	the same function
     argument have to be given in a single argument to the Fa macro.

     This macro	is also	used to	specify	the field name of a structure.

     Most often, the Fa	macro is used in the SYNOPSIS within Fo	blocks when
     documenting multi-line function prototypes.  If invoked with multiple
     arguments,	the arguments are separated by a comma.	 Furthermore, if the
     following macro is	another	Fa, the	last argument will also	have a trail-
     ing comma.

	   .Fa "const char *p"
	   .Fa "int a" "int b" "int c"
	   .Fa "char *"	size_t

     See also Fo.

     End a function context started by Fo.

     Preprocessor directive, in	particular for listing it in the SYNOPSIS.
     Historically, it was also used to document	include	files.	The latter
     usage has been deprecated in favour of In.

     Its syntax	is as follows:

	   .Fd #directive [argument ...]

	   .Fd #define sa_handler __sigaction_u.__sa_handler
	   .Fd #define SIO_MAXNFDS
	   .Fd #ifdef FS_DEBUG
	   .Ft void
	   .Fn dbg_open	"const char *"
	   .Fd #endif

     See also MANUAL STRUCTURE,	In, and	Dv.

     Command-line flag or option.  Used	when listing arguments to command-line
     utilities.	 Prints	a fixed-width hyphen `-' directly followed by each
     argument.	If no arguments	are provided, a	hyphen is printed followed by
     a space.  If the argument is a macro, a hyphen is prefixed	to the subse-
     quent macro output.

	   .Fl R Op Fl H | L | P
	   .Op Fl 1AaCcdFfgHhikLlmnopqRrSsTtux
	   .Fl type Cm d Fl name Pa CVS
	   .Fl Ar signal_number
	   .Fl o Fl

     See also Cm.

     A function	name.  Its syntax is as	follows:

	   .Fn [functype] funcname [[argtype] argname]

     Function arguments	are surrounded in parenthesis and are delimited	by
     commas.  If no arguments are specified, blank parenthesis are output.  In
     the SYNOPSIS section, this	macro starts a new output line,	and a blank
     line is automatically inserted between function definitions.

	   .Fn "int funcname" "int arg0" "int arg1"
	   .Fn funcname	"int arg0"
	   .Fn funcname	arg0

	   .Ft functype
	   .Fn funcname

     When referring to a function documented in	another	manual page, use Xr
     instead.  See also	MANUAL STRUCTURE, Fo, and Ft.

     Begin a function block.  This is a	multi-line version of Fn.  Its syntax
     is	as follows:

	   .Fo funcname

     Invocations usually occur in the following	context:

	   .Ft functype
	   .Fo funcname
	   .Fa "argtype	argname"

     A Fo scope	is closed by Fc.

     See also MANUAL STRUCTURE,	Fa, Fc,	and Ft.

     This macro	is obsolete.  No replacement markup is needed.

     It	was used to show numerical function return values in an	italic font.

     A function	type.  Its syntax is as	follows:

	   .Ft functype

     In	the SYNOPSIS section, a	new output line	is started after this macro.

	   .Ft int
	   .Ft functype
	   .Fn funcname

     See also MANUAL STRUCTURE,	Fn, and	Fo.

     Format the	FreeBSD	version	provided as an argument, or a default value if
     no	argument is provided.

	   .Fx 7.1

     See also At, Bsx, Bx, Dx, Nx, and Ox.

     This macro	is not implemented in mandoc(1).

     It	was used to include the	contents of a (header) file literally.	The
     syntax was:

	   .Hf filename

     Designate an internal or interactive command.  This is similar to Cm but
     used for instructions rather than values.

	   .Ic :wq
	   .Ic hash
	   .Ic alias

     Note that using Bd	-literal or D1 is preferred for	displaying code; the
     Ic	macro is used when referring to	specific instructions.

     The name of an include file.  This	macro is most often used in section 2,
     3,	and 9 manual pages.

     When invoked as the first macro on	an input line in the SYNOPSIS section,
     the argument is displayed in angle	brackets and preceded by "#include",
     and a blank line is inserted in front if there is a preceding function
     declaration.  In other sections, it only encloses its argument in angle
     brackets and causes no line break.

	   .In sys/types.h


     A list item.  The syntax of this macro depends on the list	type.

     Lists of type -hang, -ohang, -inset, and -diag have the following syntax:

	   .It args

     Lists of type -bullet, -dash, -enum, -hyphen and -item have the following


     with subsequent lines interpreted within the scope	of the It until	either
     a closing El or another It.

     The -tag list has the following syntax:

	   .It [args]

     Subsequent	lines are interpreted as with -bullet and family.  The line
     arguments correspond to the list's	left-hand side;	body arguments corre-
     spond to the list's contents.

     The -column list is the most complicated.	Its syntax is as follows:

	   .It cell [Ta	cell ...]
	   .It cell [<TAB> cell	...]

     The arguments consist of one or more lines	of text	and macros represent-
     ing a complete table line.	 Cells within the line are delimited by	the
     special Ta	block macro or by literal tab characters.

     Using literal tabs	is strongly discouraged	because	they are very hard to
     use correctly and mdoc code using them is very hard to read.  In particu-
     lar, a blank character is syntactically significant before	and after the
     literal tab character.  If	a word precedes	or follows the tab without an
     intervening blank,	that word is never interpreted as a macro call,	but
     always output literally.

     The tab cell delimiter may	only be	used within the	It line	itself;	on
     following lines, only the Ta macro	can be used to delimit cells, and
     portability requires that Ta is called by other macros: some parsers do
     not recognize it when it appears as the first macro on a line.

     Note that quoted strings may span tab-delimited cells on an It line.  For

	   .It "col1 , <TAB> col2 ," ;

     will preserve the whitespace before both commas, but not the whitespace
     before the	semicolon.

     See also Bl.

     Specify a library.	 The syntax is as follows:

	   .Lb library

     The library parameter may be a system library, such as libz or libpam, in
     which case	a small	library	description is printed next to the linker
     invocation; or a custom library, in which case the	library	name is
     printed in	quotes.	 This is most commonly used in the SYNOPSIS section as
     described in MANUAL STRUCTURE.

	   .Lb libz
	   .Lb libmandoc

     Denotes text that should be in a literal font mode.  Note that this is a
     presentation term and should not be used for stylistically	decorating
     technical terms.

     On	terminal output	devices, this is often indistinguishable from normal

     See also Bf, Em, No, and Sy.

     Format a hyperlink.  Its syntax is	as follows:

	   .Lk uri [name]

	   .Lk "The Project"

     See also Mt.

     Synonym for Pp.

     Display a mathematical symbol.  Its syntax	is as follows:

	   .Ms symbol

	   .Ms sigma
	   .Ms aleph

     Format a ``mailto:'' hyperlink.  Its syntax is as follows:

	   .Mt address

	   .An Kristaps	Dzonsons Aq Mt

     A one line	description of the manual's content.  This is the mandatory
     last macro	of the NAME section and	not appropriate	for other sections.

	   .Nd mdoc language reference
	   .Nd format and display UNIX manuals

     The Nd macro technically accepts child macros and terminates with a sub-
     sequent Sh	invocation.  Do	not assume this	behaviour: some	whatis(1)
     database generators are not smart enough to parse more than the line
     arguments and will	display	macros verbatim.

     See also Nm.

     The name of the manual page, or --	in particular in section 1, 6, and 8
     pages -- of an additional command or feature documented in	the manual
     page.  When first invoked,	the Nm macro expects a single argument,	the
     name of the manual	page.  Usually,	the first invocation happens in	the
     NAME section of the page.	The specified name will	be remembered and used
     whenever the macro	is called again	without	arguments later	in the page.
     The Nm macro uses Block full-implicit semantics when invoked as the first
     macro on an input line in the SYNOPSIS section; otherwise,	it uses	ordi-
     nary In-line semantics.


	   .Nm cat
	   .Op Fl benstuv
	   .Op Ar

     In	the SYNOPSIS of	section	2, 3 and 9 manual pages, use the Fn macro
     rather than Nm to mark up the name	of the manual page.

     Normal text.  Closes the scope of any preceding in-line macro.  When used
     after physical formatting macros like Em or Sy, switches back to the
     standard font face	and weight.  Can also be used to embed plain text
     strings in	macro lines using semantic annotation macros.

	   .Em italic ,	Sy bold	, No and roman

	   .Sm off
	   .Cm :C No / Ar pattern No / Ar replacement No /
	   .Sm on

     See also Em, Li, and Sy.

     Suppress a	space between the output of the	preceding macro	and the	fol-
     lowing text or macro.  Following invocation, input	is interpreted as nor-
     mal text just like	after an No macro.

     This has no effect	when invoked at	the start of a macro line.

	   .Ar name Ns = Ns Ar value
	   .Cm :M Ns Ar	pattern
	   .Fl o Ns Ar output

     See also No and Sm.

     Format the	NetBSD version provided	as an argument,	or a default value if
     no	argument is provided.

	   .Nx 5.01

     See also At, Bsx, Bx, Dx, Fx, and Ox.

     Close multi-line Oo context.

     Multi-line	version	of Op.

	   .Op Fl flag Ns Ar value

     Optional part of a	command	line.  Prints the argument(s) in brackets.
     This is most often	used in	the SYNOPSIS section of	section	1 and 8	manual

	   .Op Fl a Ar b
	   .Op Ar a | b

     See also Oo.

     Operating system version for display in the page footer.  This is the
     mandatory third macro of any mdoc file.  Its syntax is as follows:

	   .Os [system [version]]

     The optional system parameter specifies the relevant operating system or
     environment.  It is suggested to leave it unspecified, in which case
     mandoc(1) uses its	-Ios argument or, if that isn't	specified either,
     sysname and release as returned by	uname(3).

	   .Os BSD 4.3

     See also Dd and Dt.

     This macro	is obsolete.  Use Ft instead; with mandoc(1), both have	the
     same effect.

     Historical	mdoc packages described	it as ``old function type (FORTRAN)''.

     Format the	OpenBSD	version	provided as an argument, or a default value if
     no	argument is provided.

	   .Ox 4.5

     See also At, Bsx, Bx, Dx, Fx, and Nx.

     An	absolute or relative file system path, or a file or directory name.
     If	an argument is not provided, the character `~' is used as a default.

	   .Pa /usr/bin/mandoc
	   .Pa /usr/share/man/man7/mdoc.7

     See also Lk.

     Close parenthesised context opened	by Po.

     Removes the space between its argument and	the following macro.  Its syn-
     tax is as follows:

	   .Pf prefix macro arguments ...

     This is equivalent	to:

	   .No \&prefix	Ns macro arguments ...

     The prefix	argument is not	parsed for macro names or delimiters, but used
     verbatim as if it were escaped.

	   .Pf $ Ar variable_name
	   .Pf . Ar macro_name
	   .Pf 0x Ar hex_digits

     See also Ns and Sm.

     Multi-line	version	of Pq.

     Break a paragraph.	 This will assert vertical space between prior and
     subsequent	macros and/or text.

     Paragraph breaks are not needed before or after Sh	or Ss macros or	before
     displays (Bd) or lists (Bl) unless	the -compact flag is given.

     Parenthesised enclosure.

     See also Po.

     Close quoted context opened by Qo.

     In-line literal display.  This can	for example be used for	complete com-
     mand invocations and for multi-word code fragments	when more specific
     markup is not appropriate and an indented display is not desired.	While
     mandoc(1) always encloses the arguments in	single quotes, other format-
     ters usually omit the quotes on non-terminal output devices when the
     arguments have three or more characters.

     See also Dl and Bd	-literal.

     Multi-line	version	of Qq.

     Encloses its arguments in "typewriter" double-quotes.  Consider using Dq.

     See also Dq, Sq, and Qo.

     Close an Rs block.	 Does not have any tail	arguments.

     Begin a bibliographic (``reference'') block.  Does	not have any head
     arguments.	 The block macro may only contain %A, %B, %C, %D, %I, %J, %N,
     %O, %P, %Q, %R, %T, %U, and %V child macros (at least one must be speci-

	   .%A J. E. Hopcroft
	   .%A J. D. Ullman
	   .%B Introduction to Automata	Theory,	Languages, and Computation
	   .%I Addison-Wesley
	   .%C Reading,	Massachusetts
	   .%D 1979

     If	an Rs block is used within a SEE ALSO section, a vertical space	is
     asserted before the rendered output, else the block continues on the cur-
     rent line.

     Insert a standard sentence	regarding a function call's return value of 0
     on	success	and -1 on error, with the errno	libc global variable set on
     error.  Its syntax	is as follows:

	   .Rv -std [function ...]

     If	function is not	specified, the document's name set by Nm is used.
     Multiple function arguments are treated as	separate functions.

     See also Ex.

     Close single-quoted context opened	by So.

     Begin a new section.  For a list of conventional manual sections, see
     MANUAL STRUCTURE.	These sections should be used unless it's absolutely
     necessary that custom sections be used.

     Section names should be unique so that they may be	keyed by Sx.  Although
     this macro	is parsed, it should not consist of child node or it may not
     be	linked with Sx.

     See also Pp, Ss, and Sx.

     Switches the spacing mode for output generated from macros.  Its syntax
     is	as follows:

	   .Sm [on | off]

     By	default, spacing is on.	 When switched off, no white space is inserted
     between macro arguments and between the output generated from adjacent
     macros, but text lines still get normal spacing between words and sen-

     When called without an argument, the Sm macro toggles the spacing mode.
     Using this	is not recommended because it makes the	code harder to read.

     Multi-line	version	of Sq.

     Encloses its arguments in `typewriter' single-quotes.

     See also Dq, Qq, and So.

     Begin a new subsection.  Unlike with Sh, there is no convention for the
     naming of subsections.  Except DESCRIPTION, the conventional sections
     described in MANUAL STRUCTURE rarely have subsections.

     Sub-section names should be unique	so that	they may be keyed by Sx.
     Although this macro is parsed, it should not consist of child node	or it
     may not be	linked with Sx.

     See also Pp, Sh, and Sx.

     Replace an	abbreviation for a standard with the full form.	 The following
     standards are recognised.	Where multiple lines are given without a blank
     line in between, they all refer to	the same standard, and using the first
     form is recommended.

     C language	standards

	-ansiC		ANSI X3.159-1989 (``ANSI C89'')
	-ansiC-89	ANSI X3.159-1989 (``ANSI C89'')
	-isoC		ISO/IEC	9899:1990 (``ISO C90'')
	-isoC-90	ISO/IEC	9899:1990 (``ISO C90'')
			The original C standard.

	-isoC-amd1	ISO/IEC	9899/AMD1:1995 (``ISO C90, Amendment 1'')

	-isoC-tcor1	ISO/IEC	9899/TCOR1:1994	(``ISO C90, Technical
			Corrigendum 1'')

	-isoC-tcor2	ISO/IEC	9899/TCOR2:1995	(``ISO C90, Technical
			Corrigendum 2'')

	-isoC-99	ISO/IEC	9899:1999 (``ISO C99'')
			The second major version of the	C language standard.

	-isoC-2011	ISO/IEC	9899:2011 (``ISO C11'')
			The third major	version	of the C language standard.

     POSIX.1 before the	Single UNIX Specification

	-p1003.1-88	IEEE Std 1003.1-1988 (``POSIX.1'')
	-p1003.1	IEEE Std 1003.1	(``POSIX.1'')
			The original POSIX standard, based on ANSI C.

	-p1003.1-90	ISO/IEC	9945-1:1990 (``POSIX.1'')
	-iso9945-1-90	ISO/IEC	9945-1:1990 (``POSIX.1'')
			The first update of POSIX.1.

	-p1003.1b-93	IEEE Std 1003.1b-1993 (``POSIX.1'')
	-p1003.1b	IEEE Std 1003.1b (``POSIX.1'')
			Real-time extensions.

	-p1003.1c-95	IEEE Std 1003.1c-1995 (``POSIX.1'')
			POSIX thread interfaces.

	-p1003.1i-95	IEEE Std 1003.1i-1995 (``POSIX.1'')
			Technical Corrigendum.

	-p1003.1-96	ISO/IEC	9945-1:1996 (``POSIX.1'')
	-iso9945-1-96	ISO/IEC	9945-1:1996 (``POSIX.1'')
			Includes POSIX.1-1990, 1b, 1c, and 1i.

     X/Open Portability	Guide version 4	and related standards

	-xpg3		X/Open Portability Guide Issue 3 (``XPG3'')
			An XPG4	precursor, published in	1989.

	-p1003.2	IEEE Std 1003.2	(``POSIX.2'')
	-p1003.2-92	IEEE Std 1003.2-1992 (``POSIX.2'')
	-iso9945-2-93	ISO/IEC	9945-2:1993 (``POSIX.2'')
			An XCU4	precursor.

	-p1003.2a-92	IEEE Std 1003.2a-1992 (``POSIX.2'')
			Updates	to POSIX.2.

	-xpg4		X/Open Portability Guide Issue 4 (``XPG4'')
			Based on POSIX.1 and POSIX.2, published	in 1992.

     Single UNIX Specification version 1 and related standards

	-xpg4.2		X/Open Portability Guide Issue 4, Version 2
			This standard was published in 1994.  It was used as
			the basis for UNIX 95 certification.  The following
			three refer to parts of	it.


	-xcurses4.2	X/Open Curses Issue 4, Version 2 (``XCURSES4.2'')

	-p1003.1g-2000	IEEE Std 1003.1g-2000 (``POSIX.1'')
			Networking APIs, including sockets.

	-svid4		System V Interface Definition, Fourth Edition
			Published in 1995.

     Single UNIX Specification version 2 and related standards

	-susv2		Version	2 of the Single	UNIX Specification (``SUSv2'')
			This Standard was published in 1997 and	is also	called
			X/Open Portability Guide version 5.  It	was used as
			the basis for UNIX 98 certification.  The following
			refer to parts of it.

	-xbd5		X/Open Base Definitions	Issue 5	(``XBD5'')

	-xsh5		X/Open System Interfaces and Headers Issue 5

	-xcu5		X/Open Commands	and Utilities Issue 5 (``XCU5'')

	-xns5		X/Open Networking Services Issue 5 (``XNS5'')
	-xns5.2		X/Open Networking Services Issue 5.2 (``XNS5.2'')

     Single UNIX Specification version 3

	-p1003.1-2001  IEEE Std	1003.1-2001 (``POSIX.1'')
	-susv3	       Version 3 of the	Single UNIX Specification (``SUSv3'')
		       This standard is	based on C99, SUSv2, POSIX.1-1996, 1d,
		       and 1j.	It is also called X/Open Portability Guide
		       version 6.  It is used as the basis for UNIX 03 certi-

	-p1003.1-2004  IEEE Std	1003.1-2004 (``POSIX.1'')
		       The second and last Technical Corrigendum.

     Single UNIX Specification version 4

	-p1003.1-2008	IEEE Std 1003.1-2008 (``POSIX.1'')
	-susv4		Version	4 of the Single	UNIX Specification (``SUSv4'')
			This standard is also called X/Open Portability	Guide
			version	7.

			The 2013 edition incorporates Technical	Corrigendum 1.

			The 2016 edition incorporates Technical	Corrigendum 1
			and Technical Corrigendum 2.

     Other standards

	-ieee754	IEEE Std 754-1985
			Floating-point arithmetic.

			Representation of dates	and times, published in	1988.

	-iso8802-3	ISO/IEC	8802-3:1989
			Ethernet local area networks.

	-ieee1275-94	IEEE Std 1275-1994 (``Open Firmware'')

     Reference a section or subsection in the same manual page.	 The refer-
     enced section or subsection name must be identical	to the enclosed	argu-
     ment, including whitespace.


     See also Sh and Ss.

     Request a boldface	font.

     This is most often	used to	indicate importance or seriousness (not	to be
     confused with stress emphasis, see	Em).  When none	of the semantic	macros
     fit, it is	also adequate for syntax elements that have to be given	or
     that appear verbatim.

	   .Sy Warning :
	   .Sy s
	   appears in the owner	permissions, set-user-ID mode is set.
	   This	utility	replaces the former
	   .Sy dumpdir

     See also Bf, Em, Li, and No.

     Table cell	separator in Bl	-column	lists; can only	be used	below It.

     Supported only for	compatibility, do not use this in new manuals.	Even
     though the	macro name (``tradename'') suggests a semantic function, his-
     toric usage is inconsistent, mostly using it as a presentation-level
     macro to request a	small caps font.

     Supported only for	compatibility, do not use this in new manuals.	Prints
     out ``currently under development.''

     Supported only for	compatibility, do not use this in new manuals.	Prints
     out ``UNIX''.

     A variable	name.

	   .Va foo
	   .Va const char *bar;

     For function arguments and	parameters, use	Fa instead.  For declarations
     of	global variables in the	SYNOPSIS section, use Vt.

     A variable	type.

     This is also used for indicating global variables in the SYNOPSIS sec-
     tion, in which case a variable name is also specified.  Note that it
     accepts Block partial-implicit syntax when	invoked	as the first macro on
     an	input line in the SYNOPSIS section, else it accepts ordinary In-line
     syntax.  In the former case, this macro starts a new output line, and a
     blank line	is inserted in front if	there is a preceding function defini-
     tion or include directive.

	   .Vt unsigned	char
	   .Vt extern const char * const sys_signame[] ;

     For parameters in function	prototypes, use	Fa instead, for	function
     return types Ft, and for variable names outside the SYNOPSIS section Va,
     even when including a type	with the name.	See also MANUAL	STRUCTURE.

     Close a scope opened by Xo.

     Extend the	header of an It	macro or the body of a partial-implicit	block
     macro beyond the end of the input line.  This macro originally existed to
     work around the 9-argument	limit of historic roff(7).

     Link to another manual ("cross-reference").  Its syntax is	as follows:

	   .Xr name section

     Cross reference the name and section number of another man	page.

	   .Xr mandoc 1
	   .Xr mandoc 1	;
	   .Xr mandoc 1	Ns s behaviour

     The syntax	of a macro depends on its classification.  In this section,
     `-arg' refers to macro arguments, which may be followed by	zero or	more
     `parm' parameters;	`Yo' opens the scope of	a macro; and if	specified,
     `Yc' closes it out.

     The Callable column indicates that	the macro may also be called by	pass-
     ing its name as an	argument to another macro.  For	example, `.Op Fl O Ar
     file' produces `[-O file]'.  To prevent a macro call and render the macro
     name literally, escape it by prepending a zero-width space, `\&'.	For
     example, `Op \&Fl O' produces `[Fl	O]'.  If a macro is not	callable but
     its name appears as an argument to	another	macro, it is interpreted as
     opaque text.  For example,	`.Fl Sh' produces `-Sh'.

     The Parsed	column indicates whether the macro may call other macros by
     receiving their names as arguments.  If a macro is	not parsed but the
     name of another macro appears as an argument, it is interpreted as	opaque

     The Scope column, if applicable, describes	closure	rules.

   Block full-explicit
     Multi-line	scope closed by	an explicit closing macro.  All	macros con-
     tains bodies; only	Bf and (optionally) Bl contain a head.

	   .Yo [-arg [parm...]]	[head...]

	   Macro     Callable	  Parsed     Scope
	   Bd	     No		  No	     closed by Ed
	   Bf	     No		  No	     closed by Ef
	   Bk	     No		  No	     closed by Ek
	   Bl	     No		  No	     closed by El
	   Ed	     No		  No	     opened by Bd
	   Ef	     No		  No	     opened by Bf
	   Ek	     No		  No	     opened by Bk
	   El	     No		  No	     opened by Bl

   Block full-implicit
     Multi-line	scope closed by	end-of-file or implicitly by another macro.
     All macros	have bodies; some (It -bullet, -hyphen,	-dash, -enum, -item)
     don't have	heads; only one	(It in Bl -column) has multiple	heads.

	   .Yo [-arg [parm...]]	[head... [Ta head...]]

	   Macro     Callable	  Parsed     Scope
	   It	     No		  Yes	     closed by It, El
	   Nd	     No		  No	     closed by Sh
	   Nm	     No		  Yes	     closed by Nm, Sh, Ss
	   Sh	     No		  Yes	     closed by Sh
	   Ss	     No		  Yes	     closed by Sh, Ss

     Note that the Nm macro is a Block full-implicit macro only	when invoked
     as	the first macro	in a SYNOPSIS section line, else it is In-line.

   Block partial-explicit
     Like block	full-explicit, but also	with single-line scope.	 Each has at
     least a body and, in limited circumstances, a head	(Fo, Eo) and/or	tail

	   .Yo [-arg [parm...]]	[head...]
	   .Yc [tail...]

	   .Yo [-arg [parm...]]	[head...] [body...] Yc [tail...]

	   Macro     Callable	  Parsed     Scope
	   Ac	     Yes	  Yes	     opened by Ao
	   Ao	     Yes	  Yes	     closed by Ac
	   Bc	     Yes	  Yes	     closed by Bo
	   Bo	     Yes	  Yes	     opened by Bc
	   Brc	     Yes	  Yes	     opened by Bro
	   Bro	     Yes	  Yes	     closed by Brc
	   Dc	     Yes	  Yes	     opened by Do
	   Do	     Yes	  Yes	     closed by Dc
	   Ec	     Yes	  Yes	     opened by Eo
	   Eo	     Yes	  Yes	     closed by Ec
	   Fc	     Yes	  Yes	     opened by Fo
	   Fo	     No		  No	     closed by Fc
	   Oc	     Yes	  Yes	     closed by Oo
	   Oo	     Yes	  Yes	     opened by Oc
	   Pc	     Yes	  Yes	     closed by Po
	   Po	     Yes	  Yes	     opened by Pc
	   Qc	     Yes	  Yes	     opened by Oo
	   Qo	     Yes	  Yes	     closed by Oc
	   Re	     No		  No	     opened by Rs
	   Rs	     No		  No	     closed by Re
	   Sc	     Yes	  Yes	     opened by So
	   So	     Yes	  Yes	     closed by Sc
	   Xc	     Yes	  Yes	     opened by Xo
	   Xo	     Yes	  Yes	     closed by Xc

   Block partial-implicit
     Like block	full-implicit, but with	single-line scope closed by the	end of
     the line.

	   .Yo [-arg [val...]] [body...] [res...]

	   Macro     Callable	  Parsed
	   Aq	     Yes	  Yes
	   Bq	     Yes	  Yes
	   Brq	     Yes	  Yes
	   D1	     No		  Yes
	   Dl	     No		  Yes
	   Dq	     Yes	  Yes
	   En	     Yes	  Yes
	   Op	     Yes	  Yes
	   Pq	     Yes	  Yes
	   Ql	     Yes	  Yes
	   Qq	     Yes	  Yes
	   Sq	     Yes	  Yes
	   Vt	     Yes	  Yes

     Note that the Vt macro is a Block partial-implicit	only when invoked as
     the first macro in	a SYNOPSIS section line, else it is In-line.

   Special block macro
     The Ta macro can only be used below It in Bl -column lists.  It delimits
     blocks representing table cells; these blocks have	bodies,	but no heads.

	   Macro     Callable	  Parsed     Scope
	   Ta	     Yes	  Yes	     closed by Ta, It

     Closed by the end of the line, fixed argument lengths, and/or subsequent
     macros.  In-line macros have only text children.  If a number (or
     inequality) of arguments is (n), then the macro accepts an	arbitrary num-
     ber of arguments.

	   .Yo [-arg [val...]] [args...] [res...]

	   .Yo [-arg [val...]] [args...] Yc...

	   .Yo [-arg [val...]] arg0 arg1 argN

	   Macro     Callable	  Parsed     Arguments
	   %A	     No		  No	     >0
	   %B	     No		  No	     >0
	   %C	     No		  No	     >0
	   %D	     No		  No	     >0
	   %I	     No		  No	     >0
	   %J	     No		  No	     >0
	   %N	     No		  No	     >0
	   %O	     No		  No	     >0
	   %P	     No		  No	     >0
	   %Q	     No		  No	     >0
	   %R	     No		  No	     >0
	   %T	     No		  No	     >0
	   %U	     No		  No	     >0
	   %V	     No		  No	     >0
	   Ad	     Yes	  Yes	     >0
	   An	     Yes	  Yes	     >0
	   Ap	     Yes	  Yes	     0
	   Ar	     Yes	  Yes	     n
	   At	     Yes	  Yes	     1
	   Bsx	     Yes	  Yes	     n
	   Bt	     No		  No	     0
	   Bx	     Yes	  Yes	     n
	   Cd	     Yes	  Yes	     >0
	   Cm	     Yes	  Yes	     >0
	   Db	     No		  No	     1
	   Dd	     No		  No	     n
	   Dt	     No		  No	     n
	   Dv	     Yes	  Yes	     >0
	   Dx	     Yes	  Yes	     n
	   Em	     Yes	  Yes	     >0
	   Er	     Yes	  Yes	     >0
	   Es	     Yes	  Yes	     2
	   Ev	     Yes	  Yes	     >0
	   Ex	     No		  No	     n
	   Fa	     Yes	  Yes	     >0
	   Fd	     No		  No	     >0
	   Fl	     Yes	  Yes	     n
	   Fn	     Yes	  Yes	     >0
	   Fr	     Yes	  Yes	     >0
	   Ft	     Yes	  Yes	     >0
	   Fx	     Yes	  Yes	     n
	   Hf	     No		  No	     n
	   Ic	     Yes	  Yes	     >0
	   In	     No		  No	     1
	   Lb	     No		  No	     1
	   Li	     Yes	  Yes	     >0
	   Lk	     Yes	  Yes	     >0
	   Lp	     No		  No	     0
	   Ms	     Yes	  Yes	     >0
	   Mt	     Yes	  Yes	     >0
	   Nm	     Yes	  Yes	     n
	   No	     Yes	  Yes	     0
	   Ns	     Yes	  Yes	     0
	   Nx	     Yes	  Yes	     n
	   Os	     No		  No	     n
	   Ot	     Yes	  Yes	     >0
	   Ox	     Yes	  Yes	     n
	   Pa	     Yes	  Yes	     n
	   Pf	     Yes	  Yes	     1
	   Pp	     No		  No	     0
	   Rv	     No		  No	     n
	   Sm	     No		  No	     <2
	   St	     No		  Yes	     1
	   Sx	     Yes	  Yes	     >0
	   Sy	     Yes	  Yes	     >0
	   Tn	     Yes	  Yes	     >0
	   Ud	     No		  No	     0
	   Ux	     Yes	  Yes	     n
	   Va	     Yes	  Yes	     n
	   Vt	     Yes	  Yes	     >0
	   Xr	     Yes	  Yes	     2

     When a macro argument consists of one single input	character considered
     as	a delimiter, the argument gets special handling.  This does not	apply
     when delimiters appear in arguments containing more than one character.
     Consequently, to prevent special handling and just	handle it like any
     other argument, a delimiter can be	escaped	by prepending a	zero-width
     space (`\&').  In text lines, delimiters never need escaping, but may be
     used as normal punctuation.

     For many macros, when the leading arguments are opening delimiters, these
     delimiters	are put	before the macro scope,	and when the trailing argu-
     ments are closing delimiters, these delimiters are	put after the macro
     scope.  Spacing is	suppressed after opening delimiters and	before closing
     delimiters.  For example,

	   .Aq ( [ word	] ) .

     renders as:


     Opening delimiters	are:

	   (	   left	parenthesis
	   [	   left	bracket

     Closing delimiters	are:

	   .	   period
	   ,	   comma
	   :	   colon
	   ;	   semicolon
	   )	   right parenthesis
	   ]	   right bracket
	   ?	   question mark
	   !	   exclamation mark

     Note that even a period preceded by a backslash (`\.') gets this special
     handling; use `\&.' to prevent that.

     Many in-line macros interrupt their scope when they encounter delimiters,
     and resume	their scope when more arguments	follow that are	not delim-
     iters.  For example,

	   .Fl a ( b | c \*(Ba d ) e

     renders as:

	   -a (-b | -c | -d) -e

     This applies to both opening and closing delimiters, and also to the mid-
     dle delimiter, which does not suppress spacing:

	   |	   vertical bar

     As	a special case,	the predefined string \*(Ba is handled and rendered in
     the same way as a plain `|' character.  Using this	predefined string is
     not recommended in	new manuals.

   Font	handling
     In	mdoc documents,	usage of semantic markup is recommended	in order to
     have proper fonts automatically selected; only when no fitting semantic
     markup is available, consider falling back	to Physical markup macros.
     Whenever any mdoc macro switches the roff(7) font mode, it	will automati-
     cally restore the previous	font when exiting its scope.  Manually switch-
     ing the font using	the roff(7) `\f' font escape sequences is never

     This section provides an incomplete list of compatibility issues between
     mandoc and	GNU troff ("groff").

     The following problematic behaviour is found in groff:

     -	 Dd with non-standard arguments	behaves	very strangely.	 When there
	 are three arguments, they are printed verbatim.  Any other number of
	 arguments is replaced by the current date, but	without	any arguments
	 the string ``Epoch'' is printed.
     -	 Lk only accepts a single link-name argument; the remainder is misfor-
     -	 Pa does not format its	arguments when used in the FILES section under
	 certain list types.
     -	 Ta can	only be	called by other	macros,	but not	at the beginning of a
     -	 %C is not implemented (up to and including groff-1.22.2).
     -	 `\f' (font face) and `\F' (font family	face) Text Decoration escapes
	 behave	irregularly when specified within line-macro scopes.
     -	 Negative scaling units	return to prior	lines.	Instead, mandoc	trun-
	 cates them to zero.

     The following features are	unimplemented in mandoc:

     -	 Bd -file file is unsupported for security reasons.
     -	 Bd -filled does not adjust the	right margin, but is an	alias for Bd
     -	 Bd -literal does not use a literal font, but is an alias for Bd
     -	 Bd -offset center and -offset right don't work.  Groff	does not
	 implement centered and	flush-right rendering either, but produces
	 large indentations.

     man(1), mandoc(1),	eqn(7),	man(7),	mandoc_char(7),	roff(7), tbl(7)

     The web page extended documentation for the mdoc language:
     provides a	few tutorial-style pages for beginners,	an extensive style
     guide for advanced	authors, and an	alphabetic index helping to choose the
     best macros for various kinds of content.

     The mdoc language first appeared as a troff macro package in 4.4BSD.  It
     was later significantly updated by	Werner Lemberg and Ruslan Ermilov in
     groff-1.17.  The standalone implementation	that is	part of	the mandoc(1)
     utility written by	Kristaps Dzonsons appeared in OpenBSD 4.6.

     The mdoc reference	was written by Kristaps	Dzonsons <>.

FreeBSD	11.2			 July 19, 2018			  FreeBSD 11.2


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