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version 1.69, 2009/10/24 05:52:13 version 1.169, 2010/12/06 16:37:32
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 .\"     $Id$  .\"     $Id$
 .\"  .\"
 .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@kth.se>  .\" Copyright (c) 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
   .\" Copyright (c) 2010 Ingo Schwarze <schwarze@openbsd.org>
 .\"  .\"
 .\" Permission to use, copy, modify, and distribute this software for any  .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above  .\" purpose with or without fee is hereby granted, provided that the above
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 .Dd $Mdocdate$  .Dd $Mdocdate$
 .Dt MDOC 7  .Dt MDOC 7
 .Os  .Os
 .  
 .  
 .Sh NAME  .Sh NAME
 .Nm mdoc  .Nm mdoc
 .Nd mdoc language reference  .Nd mdoc language reference
 .  
 .  
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm mdoc  .Nm mdoc
 language is used to format  language is used to format
 .Bx  .Bx
 .Ux  .Ux
 manuals.  In this reference document, we describe its syntax, structure,  manuals.
 and usage.  Our reference implementation is  This reference document describes its syntax, structure, and
 .Xr mandoc 1 .  usage.
 The  The reference implementation is
   .Xr mandoc 1 ;
   the
 .Sx COMPATIBILITY  .Sx COMPATIBILITY
 section describes compatibility with  section describes compatibility with other troff \-mdoc implementations.
 .Xr groff 1 .  
 .  
 .Pp  .Pp
 An  An
 .Nm  .Nm
 document follows simple rules:  lines beginning with the control  document follows simple rules: lines beginning with the control
 character  character
 .Sq \.  .Sq \.
 are parsed for macros.  Other lines are interpreted within the scope of  are parsed for macros.
   Other lines are interpreted within the scope of
 prior macros:  prior macros:
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Sh Macro lines change control state.  \&.Sh Macro lines change control state.
 Other lines are interpreted within the current state.  Other lines are interpreted within the current state.
 .Ed  .Ed
 .  
 .  
 .Sh LANGUAGE SYNTAX  .Sh LANGUAGE SYNTAX
 .Nm  .Nm
 documents may contain only graphable 7-bit ASCII characters, the space  documents may contain only graphable 7-bit ASCII characters, the space
 character, and, in certain circumstances, the tab character.  All  character, and, in certain circumstances, the tab character.
 manuals must have  All manuals must have
 .Ux  .Ux
 line terminators.  line terminators.
 .  
 .  
 .Ss Comments  .Ss Comments
 Text following a  Text following a
 .Sq \e" ,  .Sq \e\*q ,
 whether in a macro or free-form text line, is ignored to the end of  whether in a macro or free-form text line, is ignored to the end of
 line.  A macro line with only a control character and comment escape,  line.
 .Sq \&.\e" ,  A macro line with only a control character and comment escape,
 is also ignored.  Macro lines with only a control charater and optionally  .Sq \&.\e\*q ,
 whitespace are stripped from input.  is also ignored.
 .  Macro lines with only a control character and optional whitespace are
 .  stripped from input.
 .Ss Reserved Characters  .Ss Reserved Characters
 Within a macro line, the following characters are reserved:  Within a macro line, the following characters are reserved:
 .Pp  .Pp
Line 98  Within a macro line, the following characters are rese
Line 92  Within a macro line, the following characters are rese
 .It \&|  .It \&|
 .Pq vertical bar  .Pq vertical bar
 .El  .El
 .  
 .Pp  .Pp
 Use of reserved characters is described in  Use of reserved characters is described in
 .Sx MACRO SYNTAX .  .Sx MACRO SYNTAX .
 For general use in macro lines, these characters must either be escaped  For general use in macro lines, these characters can either be escaped
 with a non-breaking space  with a non-breaking space
 .Pq Sq \e&  .Pq Sq \e&
 or, if applicable, an appropriate escape sequence used.  or, if applicable, an appropriate escape sequence can be used.
 .  
 .  
 .Ss Special Characters  .Ss Special Characters
 Special characters may occur in both macro and free-form lines.  Special characters may occur in both macro and free-form lines.
 Sequences begin with the escape character  Sequences begin with the escape character
Line 118  for two-character sequences; an open-bracket
Line 109  for two-character sequences; an open-bracket
 .Sq \&[  .Sq \&[
 for n-character sequences (terminated at a close-bracket  for n-character sequences (terminated at a close-bracket
 .Sq \&] ) ;  .Sq \&] ) ;
 or a single one-character sequence.  See  or a single one character sequence.
   See
 .Xr mandoc_char 7  .Xr mandoc_char 7
 for a complete list.  Examples include  for a complete list.
   Examples include
 .Sq \e(em  .Sq \e(em
 .Pq em-dash  .Pq em-dash
 and  and
 .Sq \ee  .Sq \ee
 .Pq back-slash .  .Pq back-slash .
 .  
 .  
 .Ss Text Decoration  .Ss Text Decoration
 Terms may be text-decorated using the  Terms may be text-decorated using the
 .Sq \ef  .Sq \ef
 escape followed by an indicator: B (bold), I, (italic), or P and R  escape followed by an indicator: B (bold), I (italic), R (Roman), or P
 (Roman, or reset).  This form is not recommended for  (revert to previous mode):
   .Pp
   .D1 \efBbold\efR \efIitalic\efP
   .Pp
   A numerical representation 3, 2, or 1 (bold, italic, and Roman,
   respectively) may be used instead.
   A text decoration is valid within
   the current font scope only: if a macro opens a font scope alongside
   its own scope, such as
   .Sx \&Bf
   .Cm \&Sy ,
   in-scope invocations of
   .Sq \ef
   are only valid within the font scope of the macro.
   If
   .Sq \ef
   is specified outside of any font scope, such as in unenclosed, free-form
   text, it will affect the remainder of the document.
   .Pp
   Note this form is
   .Em not
   recommended for
 .Nm ,  .Nm ,
 which encourages semantic, not presentation, annotation.  which encourages semantic annotation.
 .  
 .  
 .Ss Predefined Strings  .Ss Predefined Strings
 Historically,  Historically,
 .Xr groff 1  troff
 also defined a set of package-specific  also defined a set of package-specific
 .Dq predefined strings ,  .Dq predefined strings ,
 which, like  which, like
 .Sx Special Characters ,  .Sx Special Characters ,
 demark special output characters and strings by way of input codes.  mark special output characters and strings by way of input codes.
 Predefined strings are escaped with the slash-asterisk,  Predefined strings are escaped with the slash-asterisk,
 .Sq \e* :  .Sq \e* :
 single-character  single-character
Line 155  and N-character
Line 165  and N-character
 .Sq \e*[N] .  .Sq \e*[N] .
 See  See
 .Xr mandoc_char 7  .Xr mandoc_char 7
 for a complete list.  Examples include  for a complete list.
   Examples include
 .Sq \e*(Am  .Sq \e*(Am
 .Pq ampersand  .Pq ampersand
 and  and
 .Sq \e*(Ba  .Sq \e*(Ba
 .Pq vertical bar .  .Pq vertical bar .
 .  
 .  
 .Ss Whitespace  .Ss Whitespace
 In non-literal free-form lines, consecutive blocks of whitespace are  Whitespace consists of the space character.
 pruned from input and added later in the output filter, if applicable:  In free-form lines, whitespace is preserved within a line; unescaped
 .Bd -literal -offset indent  trailing spaces are stripped from input (unless in a literal context).
 These     spaces   are    pruned       from    input.  Blank free-form lines, which may include whitespace, are only permitted
 \&.Bd \-literal  within literal contexts.
 These         are              not.  
 \&.Ed  
 .Ed  
 .  
 .Pp  .Pp
 In macro lines, whitespace delimits arguments and is discarded.  If  In macro lines, whitespace delimits arguments and is discarded.
 arguments are quoted, whitespace within the quotes is retained.  If arguments are quoted, whitespace within the quotes is retained.
 .  
 .Pp  
 Blank lines are only permitted within literal contexts, as are lines  
 containing only whitespace.  Tab characters are only acceptable when  
 delimiting  
 .Sq \&Bl \-column  
 or when in a literal context.  
 .  
 .  
 .Ss Quotation  .Ss Quotation
 Macro arguments may be quoted with a double-quote to group  Macro arguments may be quoted with double-quotes to group
 space-delimited terms or to retain blocks of whitespace.  A quoted  space-delimited terms or to retain blocks of whitespace.
 argument begins with a double-quote preceded by whitespace.  The next  A quoted argument begins with a double-quote preceded by whitespace.
 double-quote not pair-wise adjacent to another double-quote terminates  The next double-quote not pairwise adjacent to another double-quote
 the literal, regardless of surrounding whitespace.  terminates the literal, regardless of surrounding whitespace.
 .  
 .Pp  .Pp
 This produces tokens  Note that any quoted text, even if it would cause a macro invocation
 .Sq a" ,  when unquoted, is considered literal text.
 .Sq b c ,  Thus, the following produces
 .Sq de ,  .Sq Op "Fl a" :
 and  
 .Sq fg" .  
 Note that any quoted term, be it argument or macro, is indiscriminately  
 considered literal text.  Thus, the following produces  
 .Sq \&Em a :  
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Em "Em a"  \&.Op "Fl a"
 .Ed  .Ed
 .  
 .Pp  .Pp
 In free-form mode, quotes are regarded as opaque text.  In free-form mode, quotes are regarded as opaque text.
 .  
 .Ss Dates  .Ss Dates
 There are several macros in  There are several macros in
 .Nm  .Nm
 that require a date argument.  The  that require a date argument.
 .Em canonical form  The canonical form for dates is the American format:
 for dates is the American format:  
 .Pp  .Pp
 .D1 Cm Month Day , Year  .D1 Cm Month Day , Year
 .Pp  .Pp
 The  The
 .Cm Day  .Cm Day
 value is an optionally zero-padded numeral.  The  value is an optionally zero-padded numeral.
   The
 .Cm Month  .Cm Month
 value is the full month name.  The  value is the full month name.
   The
 .Cm Year  .Cm Year
 value is the full four-digit year.  value is the full four-digit year.
 .Pp  .Pp
 The  Reduced form dates are broken-down canonical form dates:
 .Em non-canonical form  
 is the same as the canonical form, but without the comma between the  
 .Cm Day  
 and  
 .Cm Year  
 field.  
 .Pp  .Pp
 Lastly,  .D1 Cm Month , Year
 .Em reduced form  .D1 Cm Year
 dates range from only a  
 .Cm Year  
 to the full canonical or non-canonical form.  
 .Pp  .Pp
 Some examples of valid dates follow:  Some examples of valid dates follow:
 .Pp  .Pp
 .D1 "May, 2009" Pq reduced form  .D1 "May, 2009" Pq reduced form
 .D1 "2009" Pq reduced form  .D1 "2009" Pq reduced form
 .D1 "May 20, 2009" Pq canonical form  .D1 "May 20, 2009" Pq canonical form
 .D1 "May 20 2009" Pq non-canonical form  
 .  
 .Ss Scaling Widths  .Ss Scaling Widths
 Many macros support scaled widths for their arguments, such as  Many macros support scaled widths for their arguments, such as
 stipulating a two-inch list indentation with the following:  stipulating a two-inch list indentation with the following:
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Bl -tag -width 2i  \&.Bl -tag -width 2i
 .Ed  .Ed
 .  
 .Pp  .Pp
 The syntax for scaled widths is  The syntax for scaled widths is
 .Sq Li [+-]?[0-9]*.[0-9]*[:unit:] ,  .Sq Li [+-]?[0-9]*.[0-9]*[:unit:] ,
 where a decimal must be preceded or proceeded by at least one digit.  where a decimal must be preceded or proceeded by at least one digit.
 Negative numbers, while accepted, are truncated to zero.  The following  Negative numbers, while accepted, are truncated to zero.
 scaling units are accepted:  The following scaling units are accepted:
 .Pp  .Pp
 .Bl -tag -width Ds -offset indent -compact  .Bl -tag -width Ds -offset indent -compact
 .It c  .It c
Line 297  Using anything other than
Line 274  Using anything other than
 .Sq u ,  .Sq u ,
 or  or
 .Sq v  .Sq v
 is necessarily non-portable across output media.  See  is necessarily non-portable across output media.
   See
 .Sx COMPATIBILITY .  .Sx COMPATIBILITY .
 .  .Ss Sentence Spacing
 .  When composing a manual, make sure that sentences end at the end of
   a line.
   By doing so, front-ends 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 (
   .Ns Sq \&) ,
   .Sq \&] ,
   .Sq \&' ,
   .Sq \&" ) .
   .Pp
   The proper spacing is also intelligently preserved if a sentence ends at
   the boundary of a macro line.
   For example:
   .Pp
   .D1 \&Xr mandoc 1 \.
   .D1 \&Fl T \&Ns \&Cm ascii \.
 .Sh MANUAL STRUCTURE  .Sh MANUAL STRUCTURE
 A well-formed  A well-formed
 .Nm  .Nm
 document consists of a document prologue followed by one or more  document consists of a document prologue followed by one or more
 sections.  sections.
 .Pp  .Pp
 The prologue, which consists of (in order) the  The prologue, which consists of the
 .Sx \&Dd ,  .Sx \&Dd ,
 .Sx \&Dt ,  .Sx \&Dt ,
 and  and
 .Sx \&Os  .Sx \&Os
 macros, is required for every document.  macros in that order, is required for every document.
 .Pp  .Pp
 The first section (sections are denoted by  The first section (sections are denoted by
 .Sx \&Sh )  .Sx \&Sh )
 must be the NAME section, consisting of at least one  must be the NAME section, consisting of at least one
 .Sx \&Nm  .Sx \&Nm
 followed by  followed by
 .Sx \&Nd .  .Sx \&Nd .
 .Pp  .Pp
 Following that, convention dictates specifying at least the SYNOPSIS and  Following that, convention dictates specifying at least the
 DESCRIPTION sections, although this varies between manual sections.  .Em SYNOPSIS
   and
   .Em DESCRIPTION
   sections, although this varies between manual sections.
 .Pp  .Pp
 The following is a well-formed skeleton  The following is a well-formed skeleton
 .Nm  .Nm
Line 331  file:
Line 328  file:
 \&.Dd $\&Mdocdate$  \&.Dd $\&Mdocdate$
 \&.Dt mdoc 7  \&.Dt mdoc 7
 \&.Os  \&.Os
 \&.  
 \&.Sh NAME  \&.Sh NAME
 \&.Nm foo  \&.Nm foo
 \&.Nd a description goes here  \&.Nd a description goes here
 \&.\e\*q The next is for sections 2 & 3 only.  
 \&.\e\*q .Sh LIBRARY  \&.\e\*q .Sh LIBRARY
 \&.  \&.\e\*q For sections 2, 3, & 9 only.
   \&.\e\*q Not used in OpenBSD.
 \&.Sh SYNOPSIS  \&.Sh SYNOPSIS
 \&.Nm foo  \&.Nm foo
 \&.Op Fl options  \&.Op Fl options
 \&.Ar  \&.Ar
 \&.  
 \&.Sh DESCRIPTION  \&.Sh DESCRIPTION
 The  The
 \&.Nm  \&.Nm
 utility processes files ...  utility processes files ...
 \&.\e\*q .Sh IMPLEMENTATION NOTES  \&.\e\*q .Sh IMPLEMENTATION NOTES
 \&.\e\*q The next is for sections 1 & 8 only.  \&.\e\*q Not used in OpenBSD.
 \&.\e\*q .Sh EXIT STATUS  
 \&.\e\*q The next is for sections 2, 3, & 9 only.  
 \&.\e\*q .Sh RETURN VALUES  \&.\e\*q .Sh RETURN VALUES
 \&.\e\*q The next is for sections 1, 6, 7, & 8 only.  \&.\e\*q For sections 2, 3, & 9 only.
 \&.\e\*q .Sh ENVIRONMENT  \&.\e\*q .Sh ENVIRONMENT
   \&.\e\*q For sections 1, 6, 7, & 8 only.
 \&.\e\*q .Sh FILES  \&.\e\*q .Sh FILES
   \&.\e\*q .Sh EXIT STATUS
   \&.\e\*q For sections 1, 6, & 8 only.
 \&.\e\*q .Sh EXAMPLES  \&.\e\*q .Sh EXAMPLES
 \&.\e\*q The next is for sections 1, 4, 6, 7, & 8 only.  
 \&.\e\*q .Sh DIAGNOSTICS  \&.\e\*q .Sh DIAGNOSTICS
 \&.\e\*q The next is for sections 2, 3, & 9 only.  \&.\e\*q For sections 1, 4, 6, 7, & 8 only.
 \&.\e\*q .Sh ERRORS  \&.\e\*q .Sh ERRORS
   \&.\e\*q For sections 2, 3, & 9 only.
 \&.\e\*q .Sh SEE ALSO  \&.\e\*q .Sh SEE ALSO
 \&.\e\*q .Xr foobar 1  \&.\e\*q .Xr foobar 1
 \&.\e\*q .Sh STANDARDS  \&.\e\*q .Sh STANDARDS
Line 368  utility processes files ...
Line 364  utility processes files ...
 \&.\e\*q .Sh CAVEATS  \&.\e\*q .Sh CAVEATS
 \&.\e\*q .Sh BUGS  \&.\e\*q .Sh BUGS
 \&.\e\*q .Sh SECURITY CONSIDERATIONS  \&.\e\*q .Sh SECURITY CONSIDERATIONS
   \&.\e\*q Not used in OpenBSD.
 .Ed  .Ed
 .Pp  .Pp
 The sections in a  The sections in an
 .Nm  .Nm
 document are conventionally ordered as they appear above.  Sections  document are conventionally ordered as they appear above.
 should be composed as follows:  Sections should be composed as follows:
 .Bl -tag -width Ds -offset Ds  .Bl -ohang -offset Ds
 .It NAME  .It Em NAME
 Must contain at least one  The name(s) and a one line description of the documented material.
   The syntax for this as follows:
   .Bd -literal -offset indent
   \&.Nm name0 ,
   \&.Nm name1 ,
   \&.Nm name2
   \&.Nd a one line description
   .Ed
   .Pp
   The
 .Sx \&Nm  .Sx \&Nm
 followed by  macro(s) must precede the
   .Sx \&Nd
   macro.
   .Pp
   See
   .Sx \&Nm
   and
 .Sx \&Nd .  .Sx \&Nd .
 The name needs re-stating since one  .It Em LIBRARY
 .Nm  The name of the library containing the documented material, which is
 documents can be used for more than one utility or function, such as  assumed to be a function in a section 2, 3, or 9 manual.
 .Xr grep 1  The syntax for this is as follows:
 also being referenced as  .Bd -literal -offset indent
 .Xr egrep 1  \&.Lb libarm
   .Ed
   .Pp
   See
   .Sx \&Lb .
   .It Em SYNOPSIS
   Documents the utility invocation syntax, function call syntax, or device
   configuration.
   .Pp
   For the first, utilities (sections 1, 6, and 8), this is
   generally structured as follows:
   .Bd -literal -offset indent
   \&.Nm foo
   \&.Op Fl v
   \&.Op Fl o Ar file
   \&.Op Ar
   \&.Nm bar
   \&.Op Fl v
   \&.Op Fl o Ar file
   \&.Op Ar
   .Ed
   .Pp
   For the second, function calls (sections 2, 3, 9):
   .Bd -literal -offset indent
   \&.In header.h
   \&.Vt extern const char *global;
   \&.Ft "char *"
   \&.Fn foo "const char *src"
   \&.Ft "char *"
   \&.Fn bar "const char *src"
   .Ed
   .Pp
   And for the third, configurations (section 4):
   .Bd -literal -offset indent
   \&.Cd \*qit* at isa? port 0x2e\*q
   \&.Cd \*qit* at isa? port 0x4e\*q
   .Ed
   .Pp
   Manuals not in these sections generally don't need a
   .Em SYNOPSIS .
   .Pp
   Some macros are displayed differently in the
   .Em SYNOPSIS
   section, particularly
   .Sx \&Nm ,
   .Sx \&Cd ,
   .Sx \&Fd ,
   .Sx \&Fn ,
   .Sx \&Fo ,
   .Sx \&In ,
   .Sx \&Vt ,
 and  and
 .Xr fgrep 1 .  .Sx \&Ft .
 .It LIBRARY  All of these macros are output on their own line.
 .It SYNOPSIS  If two such dissimilar macros are pairwise invoked (except for
 .It DESCRIPTION  .Sx \&Ft
 .It IMPLEMENTATION NOTES  before
 .It EXIT STATUS  .Sx \&Fo
 .It RETURN VALUES  or
 .It ENVIRONMENT  .Sx \&Fn ) ,
 .It FILES  they are separated by a vertical space, unless in the case of
 .It EXAMPLES  .Sx \&Fo ,
 .It DIAGNOSTICS  .Sx \&Fn ,
 .It ERRORS  and
 .It SEE ALSO  .Sx \&Ft ,
 .It STANDARDS  which are always separated by vertical space.
 .It HISTORY  .Pp
 .It AUTHORS  When text and macros following an
 .It CAVEATS  .Sx \&Nm
 .It BUGS  macro starting an input line span multiple output lines,
 .It SECURITY CONSIDERATIONS  all output lines but the first will be indented to align
   with the text immediately following the
   .Sx \&Nm
   macro, up to the next
   .Sx \&Nm ,
   .Sx \&Sh ,
   or
   .Sx \&Ss
   macro or the end of an enclosing block, whichever comes first.
   .It Em DESCRIPTION
   This expands upon the brief, one line description in
   .Em NAME .
   It usually contains a breakdown of the options (if documenting a
   command), such as:
   .Bd -literal -offset indent
   The arguments are as follows:
   \&.Bl \-tag \-width Ds
   \&.It Fl v
   Print verbose information.
   \&.El
   .Ed
   .Pp
   Manuals not documenting a command won't include the above fragment.
   .It Em IMPLEMENTATION NOTES
   Implementation-specific notes should be kept here.
   This is useful when implementing standard functions that may have side
   effects or notable algorithmic implications.
   .It Em RETURN VALUES
   This section documents the
   return values of functions in sections 2, 3, and 9.
   .Pp
   See
   .Sx \&Rv .
   .It Em ENVIRONMENT
   Lists the environment variables used by the utility,
   and explains the syntax and semantics of their values.
   The
   .Xr environ 7
   manual provides examples of typical content and formatting.
   .Pp
   See
   .Sx \&Ev .
   .It Em FILES
   Documents files used.
   It's helpful to document both the file name and a short description of how
   the file is used (created, modified, etc.).
   .Pp
   See
   .Sx \&Pa .
   .It Em EXIT STATUS
   This section documents the
   command exit status for section 1, 6, and 8 utilities.
   Historically, this information was described in
   .Em DIAGNOSTICS ,
   a practise that is now discouraged.
   .Pp
   See
   .Sx \&Ex .
   .It Em EXAMPLES
   Example usages.
   This often contains snippets of well-formed, well-tested invocations.
   Make sure that examples work properly!
   .It Em DIAGNOSTICS
   Documents error conditions.
   This is most useful in section 4 manuals.
   Historically, this section was used in place of
   .Em EXIT STATUS
   for manuals in sections 1, 6, and 8; however, this practise is
   discouraged.
   .Pp
   See
   .Sx \&Bl
   .Fl diag .
   .It Em ERRORS
   Documents error handling in sections 2, 3, and 9.
   .Pp
   See
   .Sx \&Er .
   .It Em SEE ALSO
   References other manuals with related topics.
   This section should exist for most manuals.
   Cross-references should conventionally be ordered first by section, then
   alphabetically.
   .Pp
   See
   .Sx \&Xr .
   .It Em STANDARDS
   References any standards implemented or used.
   If not adhering to any standards, the
   .Em HISTORY
   section should be used instead.
   .Pp
   See
   .Sx \&St .
   .It Em HISTORY
   A brief history of the subject, including where support first appeared.
   .It Em AUTHORS
   Credits to the person or persons who wrote the code and/or documentation.
   Authors should generally be noted by both name and email address.
   .Pp
   See
   .Sx \&An .
   .It Em CAVEATS
   Common misuses and misunderstandings should be explained
   in this section.
   .It Em BUGS
   Known bugs, limitations, and work-arounds should be described
   in this section.
   .It Em SECURITY CONSIDERATIONS
   Documents any security precautions that operators should consider.
 .El  .El
 .  
 .  
 .Sh MACRO SYNTAX  .Sh MACRO SYNTAX
 Macros are one to three three characters in length and begin with a  Macros are one to three three characters in length and begin with a
 control character ,  control character,
 .Sq \&. ,  .Sq \&. ,
 at the beginning of the line.  An arbitrary amount of whitespace may  at the beginning of the line.
 sit between the control character and the macro name.  Thus, the  An arbitrary amount of whitespace may sit between the control character
 following are equivalent:  and the macro name.
   Thus, the following are equivalent:
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Pp  \&.Pp
 \&.\ \ \ \&Pp  \&.\ \ \ \&Pp
 .Ed  .Ed
 .  
 .Pp  .Pp
 The syntax of a macro depends on its classification.  In this section,  The syntax of a macro depends on its classification.
   In this section,
 .Sq \-arg  .Sq \-arg
 refers to macro arguments, which may be followed by zero or more  refers to macro arguments, which may be followed by zero or more
 .Sq parm  .Sq parm
Line 431  parameters;
Line 601  parameters;
 opens the scope of a macro; and if specified,  opens the scope of a macro; and if specified,
 .Sq \&Yc  .Sq \&Yc
 closes it out.  closes it out.
 .  
 .Pp  .Pp
 The  The
 .Em Callable  .Em Callable
 column indicates that the macro may be called subsequent to the initial  column indicates that the macro may also be called by passing its name
 line-macro.  If a macro is not callable, then its invocation after the  as an argument to another macro.
 initial line macro is interpreted as opaque text, such that  If a macro is not callable but its name appears as an argument
   to another macro, it is interpreted as opaque text.
   For example,
 .Sq \&.Fl \&Sh  .Sq \&.Fl \&Sh
 produces  produces
 .Sq Fl \&Sh .  .Sq Fl \&Sh .
 .  
 .Pp  .Pp
 The  The
 .Em Parsable  .Em Parsed
 column indicates whether the macro may be followed by further  column indicates whether the macro may call other macros by receiving
 (ostensibly callable) macros.  If a macro is not parsable, subsequent  their names as arguments.
 macro invocations on the line will be interpreted as opaque text.  If a macro is not parsed but the name of another macro appears
 .  as an argument, it is interpreted as opaque text.
 .Pp  .Pp
 The  The
 .Em Scope  .Em Scope
 column, if applicable, describes closure rules.  column, if applicable, describes closure rules.
 .  
 .  
 .Ss Block full-explicit  .Ss Block full-explicit
 Multi-line scope closed by an explicit closing macro.  All macros  Multi-line scope closed by an explicit closing macro.
 contains bodies; only  All macros contains bodies; only
 .Sx \&Bf  .Sx \&Bf
 contains a head.  contains a head.
 .Bd -literal -offset indent  .Bd -literal -offset indent
Line 465  contains a head.
Line 633  contains a head.
 \(lBbody...\(rB  \(lBbody...\(rB
 \&.Yc  \&.Yc
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXX"  .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsedX" "closed by XXX"
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Scope
 .It Sx \&Bd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ed  .It Sx \&Bd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ed
 .It Sx \&Bf  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ef  .It Sx \&Bf  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ef
 .It Sx \&Bk  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ek  .It Sx \&Bk  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ek
Line 478  contains a head.
Line 645  contains a head.
 .It Sx \&Ek  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bk  .It Sx \&Ek  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bk
 .It Sx \&El  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bl  .It Sx \&El  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bl
 .El  .El
 .  
 .  
 .Ss Block full-implicit  .Ss Block full-implicit
 Multi-line scope closed by end-of-file or implicitly by another macro.  Multi-line scope closed by end-of-file or implicitly by another macro.
 All macros have bodies; some  All macros have bodies; some
Line 492  All macros have bodies; some
Line 657  All macros have bodies; some
 .Pc  .Pc
 don't have heads; only one  don't have heads; only one
 .Po  .Po
 .Sx \&It Fl column  .Sx \&It
 .Pc  in
   .Sx \&Bl Fl column
   .Pc
 has multiple heads.  has multiple heads.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB  \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB
 \(lBbody...\(rB  \(lBbody...\(rB
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXXXXXXXXXX"  .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsedX" "closed by XXXXXXXXXXX"
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Scope
 .It Sx \&It  Ta    \&No     Ta    Yes      Ta    closed by Sx \&It , Sx \&El  .It Sx \&It  Ta    \&No     Ta    Yes      Ta    closed by Sx \&It , Sx \&El
 .It Sx \&Nd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh  .It Sx \&Nd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh
   .It Sx \&Nm  Ta    \&No     Ta  Yes Ta closed by Sx \&Nm , Sx \&Sh , Sx \&Ss
 .It Sx \&Sh  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh  .It Sx \&Sh  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh
 .It Sx \&Ss  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh , Sx \&Ss  .It Sx \&Ss  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh , Sx \&Ss
 .El  .El
 .  .Pp
 .  Note that the
   .Sx \&Nm
   macro is a
   .Sx Block full-implicit
   macro only when invoked as the first macro
   in a
   .Em SYNOPSIS
   section line, else it is
   .Sx In-line .
 .Ss Block partial-explicit  .Ss Block partial-explicit
 Like block full-explicit, but also with single-line scope.  Each  Like block full-explicit, but also with single-line scope.
 has at least a body and, in limited circumstances, a head  Each has at least a body and, in limited circumstances, a head
 .Po  .Po
 .Sx \&Fo ,  .Sx \&Fo ,
 .Sx \&Eo  .Sx \&Eo
Line 527  and/or tail
Line 702  and/or tail
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB \  \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB \
 \(lBbody...\(rB \&Yc \(lBtail...\(rB  \(lBbody...\(rB \&Yc \(lBtail...\(rB
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset indent  .Bl -column "MacroX" "CallableX" "ParsedX" "closed by XXXX" -compact -offset indent
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Scope
 .It Sx \&Ac  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Ao  .It Sx \&Ac  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Ao
 .It Sx \&Ao  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ac  .It Sx \&Ao  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ac
 .It Sx \&Bc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Bo  .It Sx \&Bc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Bo
Line 556  and/or tail
Line 730  and/or tail
 .It Sx \&Xc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Xo  .It Sx \&Xc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Xo
 .It Sx \&Xo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Xc  .It Sx \&Xo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Xc
 .El  .El
 .  
 .  
 .Ss Block partial-implicit  .Ss Block partial-implicit
 Like block full-implicit, but with single-line scope closed by  Like block full-implicit, but with single-line scope closed by
 .Sx Reserved Characters  .Sx Reserved Characters
Line 565  or end of line.
Line 737  or end of line.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB  \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset indent  .Bl -column "MacroX" "CallableX" "ParsedX" -compact -offset indent
 .It Em Macro Ta Em Callable Ta Em Parsable  .It Em Macro Ta Em Callable Ta Em Parsed
 .It Sx \&Aq  Ta    Yes      Ta    Yes  .It Sx \&Aq  Ta    Yes      Ta    Yes
 .It Sx \&Bq  Ta    Yes      Ta    Yes  .It Sx \&Bq  Ta    Yes      Ta    Yes
 .It Sx \&Brq Ta    Yes      Ta    Yes  .It Sx \&Brq Ta    Yes      Ta    Yes
Line 580  or end of line.
Line 751  or end of line.
 .It Sx \&Ql  Ta    Yes      Ta    Yes  .It Sx \&Ql  Ta    Yes      Ta    Yes
 .It Sx \&Qq  Ta    Yes      Ta    Yes  .It Sx \&Qq  Ta    Yes      Ta    Yes
 .It Sx \&Sq  Ta    Yes      Ta    Yes  .It Sx \&Sq  Ta    Yes      Ta    Yes
   .It Sx \&Vt  Ta    Yes      Ta    Yes
 .El  .El
 .  .Pp
 .  Note that the
   .Sx \&Vt
   macro is a
   .Sx Block partial-implicit
   only when invoked as the first macro
   in a
   .Em SYNOPSIS
   section line, else it is
   .Sx In-line .
 .Ss In-line  .Ss In-line
 Closed by  Closed by
 .Sx Reserved Characters ,  .Sx Reserved Characters ,
 end of line, fixed argument lengths, and/or subsequent macros.  In-line  end of line, fixed argument lengths, and/or subsequent macros.
 macros have only text children.  If a number (or inequality) of  In-line macros have only text children.
 arguments is  If a number (or inequality) of arguments is
 .Pq n ,  .Pq n ,
 then the macro accepts an arbitrary number of arguments.  then the macro accepts an arbitrary number of arguments.
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB \(lbres...\(rb  \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB \(lBres...\(rB
   
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB Yc...  \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB Yc...
   
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN  \&.Yo \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset indent  .Bl -column "MacroX" "CallableX" "ParsedX" "Arguments" -compact -offset indent
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments  .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Arguments
 .It Sx \&%A  Ta    \&No     Ta    \&No     Ta    >0  .It Sx \&%A  Ta    \&No     Ta    \&No     Ta    >0
 .It Sx \&%B  Ta    \&No     Ta    \&No     Ta    >0  .It Sx \&%B  Ta    \&No     Ta    \&No     Ta    >0
 .It Sx \&%C  Ta    \&No     Ta    \&No     Ta    >0  .It Sx \&%C  Ta    \&No     Ta    \&No     Ta    >0
Line 627  then the macro accepts an arbitrary number of argument
Line 806  then the macro accepts an arbitrary number of argument
 .It Sx \&Cd  Ta    Yes      Ta    Yes      Ta    >0  .It Sx \&Cd  Ta    Yes      Ta    Yes      Ta    >0
 .It Sx \&Cm  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Cm  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Db  Ta    \&No     Ta    \&No     Ta    1  .It Sx \&Db  Ta    \&No     Ta    \&No     Ta    1
 .It Sx \&Dd  Ta    \&No     Ta    \&No     Ta    >0  .It Sx \&Dd  Ta    \&No     Ta    \&No     Ta    n
 .It Sx \&Dt  Ta    \&No     Ta    \&No     Ta    n  .It Sx \&Dt  Ta    \&No     Ta    \&No     Ta    n
 .It Sx \&Dv  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Dv  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Dx  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Dx  Ta    Yes      Ta    Yes      Ta    n
Line 661  then the macro accepts an arbitrary number of argument
Line 840  then the macro accepts an arbitrary number of argument
 .It Sx \&Ot  Ta    \&No     Ta    \&No     Ta    n  .It Sx \&Ot  Ta    \&No     Ta    \&No     Ta    n
 .It Sx \&Ox  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Ox  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Pa  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Pa  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Pf  Ta    \&No     Ta    Yes      Ta    1  .It Sx \&Pf  Ta    Yes      Ta    Yes      Ta    1
 .It Sx \&Pp  Ta    \&No     Ta    \&No     Ta    0  .It Sx \&Pp  Ta    \&No     Ta    \&No     Ta    0
 .It Sx \&Rv  Ta    \&No     Ta    \&No     Ta    n  .It Sx \&Rv  Ta    \&No     Ta    \&No     Ta    n
 .It Sx \&Sm  Ta    \&No     Ta    \&No     Ta    1  .It Sx \&Sm  Ta    \&No     Ta    \&No     Ta    1
Line 673  then the macro accepts an arbitrary number of argument
Line 852  then the macro accepts an arbitrary number of argument
 .It Sx \&Ux  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Ux  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Va  Ta    Yes      Ta    Yes      Ta    n  .It Sx \&Va  Ta    Yes      Ta    Yes      Ta    n
 .It Sx \&Vt  Ta    Yes      Ta    Yes      Ta    >0  .It Sx \&Vt  Ta    Yes      Ta    Yes      Ta    >0
 .It Sx \&Xr  Ta    Yes      Ta    Yes      Ta    >0, <3  .It Sx \&Xr  Ta    Yes      Ta    Yes      Ta    >0
 .It Sx \&br  Ta    \&No     Ta    \&No     Ta    0  .It Sx \&br  Ta    \&No     Ta    \&No     Ta    0
 .It Sx \&sp  Ta    \&No     Ta    \&No     Ta    1  .It Sx \&sp  Ta    \&No     Ta    \&No     Ta    1
 .El  .El
 .  
 .  
 .Sh REFERENCE  .Sh REFERENCE
 This section is a canonical reference of all macros, arranged  This section is a canonical reference of all macros, arranged
 alphabetically.  For the scoping of individual macros, see  alphabetically.
   For the scoping of individual macros, see
 .Sx MACRO SYNTAX .  .Sx MACRO SYNTAX .
 .  
 .Ss \&%A  .Ss \&%A
 Author name of an  Author name of an
 .Sx \&Rs  .Sx \&Rs
 block.  Multiple authors should each be accorded their own  block.
   Multiple authors should each be accorded their own
 .Sx \%%A  .Sx \%%A
 line.  Author names should be ordered with full or abbreviated  line.
 forename(s) first, then full surname.  Author names should be ordered with full or abbreviated forename(s)
 .  first, then full surname.
 .Ss \&%B  .Ss \&%B
 Book title of an  Book title of an
 .Sx \&Rs  .Sx \&Rs
 block.  This macro may also be used in a non-bibliographic context when  block.
   This macro may also be used in a non-bibliographic context when
 referring to book titles.  referring to book titles.
 .  
 .Ss \&%C  .Ss \&%C
 Publication city or location of an  Publication city or location of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .Pp  
 .Em Remarks :  
 this macro is not implemented in  
 .Xr groff 1 .  
 .  
 .Ss \&%D  .Ss \&%D
 Publication date of an  Publication date of an
 .Sx \&Rs  .Sx \&Rs
 block.  This should follow the reduced syntax for  block.
   This should follow the reduced or canonical form syntax described in
 .Sx Dates .  .Sx Dates .
 Canonical or non-canonical form is not necessary since publications are  
 often referenced only by year, or month and year.  
 .  
 .Ss \&%I  .Ss \&%I
 Publisher or issuer name of an  Publisher or issuer name of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%J  .Ss \&%J
 Journal name of an  Journal name of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%N  .Ss \&%N
 Issue number (usually for journals) of an  Issue number (usually for journals) of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%O  .Ss \&%O
 Optional information of an  Optional information of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%P  .Ss \&%P
 Book or journal page number of an  Book or journal page number of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%Q  .Ss \&%Q
 Institutional author (school, government, etc.) of an  Institutional author (school, government, etc.) of an
 .Sx \&Rs  .Sx \&Rs
 block.  Multiple institutional authors should each be accorded their own  block.
   Multiple institutional authors should each be accorded their own
 .Sx \&%Q  .Sx \&%Q
 line.  line.
 .  
 .Ss \&%R  .Ss \&%R
 Technical report name of an  Technical report name of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&%T  .Ss \&%T
 Article title of an  Article title of an
 .Sx \&Rs  .Sx \&Rs
 block.  This macro may also be used in a non-bibliographical context  block.
 when referring to article titles.  This macro may also be used in a non-bibliographical context when
 .  referring to article titles.
 .Ss \&%U  .Ss \&%U
 URI of current document.  URI of reference document.
 .  
 .Ss \&%V  .Ss \&%V
 Volume number of an  Volume number of an
 .Sx \&Rs  .Sx \&Rs
 block.  block.
 .  
 .Ss \&Ac  .Ss \&Ac
 Closes an  Close an
 .Sx \&Ao  .Sx \&Ao
 block.  Does not have any tail arguments.  block.
 .  Does not have any tail arguments.
 .Ss \&Ad  .Ss \&Ad
 Address construct: usually in the context of an computational address in  Memory address.
 memory, not a physical (post) address.  Do not use this for postal addresses.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Ad [0,$]
 \&.Ad [0,$]  .D1 \&.Ad 0x00000000
 \&.Ad 0x00000000  
 .Ed  
 .  
 .Ss \&An  .Ss \&An
 Author name.  This macro may alternatively accepts the following  Author name.
 arguments, although these may not be specified along with a parameter:  Requires either the name of an author or one of the following arguments:
 .Bl -tag -width 12n -offset indent  .Pp
   .Bl -tag -width "-nosplitX" -offset indent -compact
 .It Fl split  .It Fl split
 Renders a line break before each author listing.  Start a new output line before each subsequent invocation of
   .Sx \&An .
 .It Fl nosplit  .It Fl nosplit
 The opposite of  The opposite of
 .Fl split .  .Fl split .
 .El  .El
 .Pp  .Pp
 In the AUTHORS section, the default is not to split the first author  The default is
 listing, but all subsequent author listings, whether or not they're  .Fl nosplit .
 interspersed by other macros or text, are split.  Thus, specifying  The effect of selecting either of the
 .Fl split  .Fl split
 will cause the first listing also to be split.  If not in the AUTHORS  modes ends at the beginning of the
 section, the default is not to split.  .Em AUTHORS
   section.
   In the
   .Em AUTHORS
   section, the default is
   .Fl nosplit
   for the first author listing and
   .Fl split
   for all other author listings.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.An -nosplit
 \&.An -nosplit  .D1 \&.An Kristaps Dzonsons \&Aq kristaps@bsd.lv
 \&.An J. E. Hopcraft ,  
 \&.An J. D. Ullman .  
 .Ed  
 .Pp  
 .Em Remarks :  
 the effects of  
 .Fl split  
 or  
 .Fl nosplit  
 are re-set when entering the AUTHORS section, so if one specifies  
 .Sx \&An Fl nosplit  
 in the general document body, it must be re-specified in the AUTHORS  
 section.  
 .  
 .Ss \&Ao  .Ss \&Ao
 Begins a block enclosed by angled brackets.  Does not have any head  Begin a block enclosed by angle brackets.
 arguments.  Does not have any head arguments.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Fl -key= \&Ns \&Ao \&Ar val \&Ac
 \&.Fl -key= Ns Ao Ar val Ac  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Aq .  .Sx \&Aq .
 .  
 .Ss \&Ap  .Ss \&Ap
 Inserts an apostrophe without any surrounding white-space.  This is  Inserts an apostrophe without any surrounding whitespace.
 generally used as a grammatic device when referring to the verb form of  This is generally used as a grammatical device when referring to the verb
 a function:  form of a function.
 .Bd -literal -offset indent  .Pp
 \&.Fn execve Ap d  Examples:
 .Ed  .D1 \&.Fn execve \&Ap d
 .  
 .Ss \&Aq  .Ss \&Aq
 Encloses its arguments in angled brackets.  Encloses its arguments in angle brackets.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Fl -key= \&Ns \&Aq \&Ar val
 \&.Fl -key= Ns Aq Ar val  
 .Ed  
 .Pp  .Pp
 .Em Remarks :  .Em Remarks :
 this macro is often abused for rendering URIs, which should instead use  this macro is often abused for rendering URIs, which should instead use
Line 856  statements, which should use
Line 1006  statements, which should use
 .Pp  .Pp
 See also  See also
 .Sx \&Ao .  .Sx \&Ao .
 .  
 .Ss \&Ar  .Ss \&Ar
 Command arguments.  If an argument is not provided, the string  Command arguments.
 .Dq file ...  If an argument is not provided, the string
   .Dq file ...\&
 is used as a default.  is used as a default.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Fl o \&Ns \&Ar file1
 \&.Fl o Ns Ar file1  .D1 \&.Ar
 \&.Ar  .D1 \&.Ar arg1 , arg2 .
 \&.Ar arg1 , arg2 .  
 .Ed  
 .  
 .Ss \&At  .Ss \&At
 Formats an AT&T version.  Accepts at most one parameter:  Formats an AT&T version.
 .Bl -tag -width 12n -offset indent  Accepts one optional argument:
   .Pp
   .Bl -tag -width "v[1-7] | 32vX" -offset indent -compact
 .It Cm v[1-7] | 32v  .It Cm v[1-7] | 32v
 A version of  A version of
 .At .  .At .
 .It Cm V[.[1-4]]?  .It Cm V[.[1-4]]?
 A system version of  A version of
 .At .  .At V .
 .El  .El
 .Pp  .Pp
 Note that these parameters do not begin with a hyphen.  Note that these arguments do not begin with a hyphen.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.At
 \&.At  .D1 \&.At V.1
 \&.At V.1  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Bsx ,  .Sx \&Bsx ,
Line 897  See also
Line 1044  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Bc  .Ss \&Bc
 Closes a  Close a
 .Sx \&Bo  .Sx \&Bo
 block.  Does not have any tail arguments.  block.
 .  Does not have any tail arguments.
 .Ss \&Bd  .Ss \&Bd
 Begins a display block.  A display is collection of macros or text which  Begin a display block.
 may be collectively offset or justified in a manner different from that  Its syntax is as follows:
 of the enclosing context.  By default, the block is preceded by a  .Bd -ragged -offset indent
 vertical space.  .Pf \. Sx \&Bd
   .Fl Ns Ar type
   .Op Fl offset Ar width
   .Op Fl compact
   .Ed
 .Pp  .Pp
 Each display is associated with a type, which must be one of the  Display blocks are used to select a different indentation and
 following arguments:  justification than the one used by the surrounding text.
 .Bl -tag -width 12n -offset indent  They may contain both macro lines and free-form text lines.
 .It Fl ragged  By default, a display block is preceded by a vertical space.
 Only left-justify the block.  .Pp
 .It Fl unfilled  The
 Do not justify the block at all.  .Ar type
   must be one of the following:
   .Bl -tag -width 13n -offset indent
   .It Fl centered
   Centre-justify each line.
   Using this display type is not recommended; many
   .Nm
   implementations render it poorly.
 .It Fl filled  .It Fl filled
 Left- and right-justify the block.  Left- and right-justify the block.
 .It Fl literal  .It Fl literal
 Alias for  Do not justify the block at all.
 .Fl unfilled .  Preserve white space as it appears in the input.
 .It Fl centered  .It Fl ragged
 Centre-justify each line.  Only left-justify the block.
   .It Fl unfilled
   An alias for
   .Fl literal .
 .El  .El
 .Pp  .Pp
 The type must be provided first.  Secondary arguments are as follows:  The
 .Bl -tag -width 12n -offset indent  .Ar type
   must be provided first.
   Additional arguments may follow:
   .Bl -tag -width 13n -offset indent
 .It Fl offset Ar width  .It Fl offset Ar width
 Offset by the value of  Indent the display by the
 .Ar width ,  .Ar width ,
 which is interpreted as one of the following, specified in order:  which may be one of the following:
 .Bl -item  .Bl -item
 .It  .It
 As one of the pre-defined strings  One of the pre-defined strings
 .Ar indent ,  .Cm indent ,
 the width of standard indentation;  the width of standard indentation;
 .Ar indent-two ,  .Cm indent-two ,
 twice  twice
 .Ar indent ;  .Cm indent ;
 .Ar left ,  .Cm left ,
 which has no effect ;  which has no effect;
 .Ar right ,  .Cm right ,
 which justifies to the right margin; and  which justifies to the right margin; or
 .Ar center ,  .Cm center ,
 which aligns around an imagined centre axis.  which aligns around an imagined centre axis.
 .It  .It
 As a precalculated width for a named macro.  The most popular is the  A macro invocation, which selects a predefined width
 imaginary macro  associated with that macro.
   The most popular is the imaginary macro
 .Ar \&Ds ,  .Ar \&Ds ,
 which resolves to  which resolves to
 .Ar 6n .  .Sy 6n .
 .It  .It
 As a scaling unit following the syntax described in  A width using the syntax described in
 .Sx Scaling Widths .  .Sx Scaling Widths .
 .It  .It
 As the calculated string length of the opaque string.  An arbitrary string, which indents by the length of this string.
 .El  .El
 .Pp  .Pp
 If unset, it will revert to the value of  When the argument is missing,
 .Ar 8n  .Fl offset
 as described in  is ignored.
 .Sx Scaling Widths .  
 .It Fl compact  .It Fl compact
 Do not assert a vertical space before the block.  Do not assert vertical space before the display.
 .It Fl file Ar file  
 Prepend the file  
 .Ar file  
 before any text or macros within the block.  
 .El  .El
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Bd \-unfilled \-offset two-indent \-compact  \&.Bd \-literal \-offset indent \-compact
    Hello       world.     Hello       world.
 \&.Ed  \&.Ed
 .Ed  .Ed
Line 981  See also
Line 1140  See also
 .Sx \&D1  .Sx \&D1
 and  and
 .Sx \&Dl .  .Sx \&Dl .
 .  
 .Ss \&Bf  .Ss \&Bf
   Change the font mode for a scoped block of text.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Bf
   .Oo
   .Fl emphasis | literal | symbolic |
   .Cm \&Em | \&Li | \&Sy
   .Oc
   .Ed
   .Pp
   The
   .Fl emphasis
   and
   .Cm \&Em
   argument are equivalent, as are
   .Fl symbolic
   and
   .Cm \&Sy ,
   and
   .Fl literal
   and
   .Cm \&Li .
   Without an argument, this macro does nothing.
   The font mode continues until broken by a new font mode in a nested
   scope or
   .Sx \&Ef
   is encountered.
   .Pp
   See also
   .Sx \&Li ,
   .Sx \&Ef ,
   .Sx \&Em ,
   and
   .Sx \&Sy .
 .Ss \&Bk  .Ss \&Bk
   Keep the output generated from each macro input line together
   on one single output line.
   Line breaks in free-form text lines are unaffected.
   The syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Bk Fl words
   .Pp
   The
   .Fl words
   argument is required; additional arguments are ignored.
   .Pp
   The following example will not break within each
   .Sx \&Op
   macro line:
   .Bd -literal -offset indent
   \&.Bk \-words
   \&.Op Fl f Ar flags
   \&.Op Fl o Ar output
   \&.Ek
   .Ed
   .Pp
   Be careful in using over-long lines within a keep block!
   Doing so will clobber the right margin.
 .Ss \&Bl  .Ss \&Bl
 .  Begin a list.
   Lists consist of items started by the
   .Sx \&It
   macro, containing a head or a body or both.
   The list syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Bl
   .Fl Ns Ar type
   .Op Fl width Ar val
   .Op Fl offset Ar val
   .Op Fl compact
   .Op HEAD ...
   .Ed
   .Pp
   The list
   .Ar type
   is mandatory and must be specified first.
   The
   .Fl width
   and
   .Fl offset
   arguments accept
   .Sx Scaling Widths
   or use the length of the given string.
   The
   .Fl offset
   is a global indentation for the whole list, affecting both item heads
   and bodies.
   For those list types supporting it, the
   .Fl width
   argument requests an additional indentation of item bodies,
   to be added to the
   .Fl offset .
   Unless the
   .Fl compact
   argument is specified, list entries are separated by vertical space.
   .Pp
   A list must specify one of the following list types:
   .Bl -tag -width 12n -offset indent
   .It Fl 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
   .Fl width
   argument.
   .It Fl column
   A columnated list.
   The
   .Fl width
   argument has no effect; instead, each argument specifies the width
   of one column, using either the
   .Sx Scaling Widths
   syntax or the string length of the argument.
   If the first line of the body of a
   .Fl column
   list is not an
   .Sx \&It
   macro line,
   .Sx \&It
   contexts spanning one input line each are implied until an
   .Sx \&It
   macro line is encountered, at which point items start being interpreted as
   described in the
   .Sx \&It
   documentation.
   .It Fl dash
   Like
   .Fl bullet ,
   except that dashes are used in place of bullets.
   .It Fl diag
   Like
   .Fl inset ,
   except that item heads are not parsed for macro invocations.
   .\" but with additional formatting to the head.
   .It Fl enum
   A numbered list.
   Formatted like
   .Fl bullet ,
   except that cardinal numbers are used in place of bullets,
   starting at 1.
   .It Fl hang
   Like
   .Fl tag ,
   except that the first lines of item bodies are not indented, but follow
   the item heads like in
   .Fl inset
   lists.
   .It Fl hyphen
   Synonym for
   .Fl dash .
   .It Fl inset
   Item bodies follow items heads on the same line, using normal inter-word
   spacing.
   Bodies are not indented, and the
   .Fl width
   argument is ignored.
   .It Fl item
   No item heads can be specified, and none are printed.
   Bodies are not indented, and the
   .Fl width
   argument is ignored.
   .It Fl ohang
   Item bodies start on the line following item heads and are not indented.
   The
   .Fl width
   argument is ignored.
   .It Fl tag
   Item bodies are indented according to the
   .Fl width
   argument.
   When an item head fits inside the indentation, the item body follows
   this head on the same output line.
   Otherwise, the body starts on the output line following the head.
   .El
   .Pp
   See also
   .Sx \&El
   and
   .Sx \&It .
 .Ss \&Bo  .Ss \&Bo
 Begins a block enclosed by square brackets.  Does not have any head  Begin a block enclosed by square brackets.
 arguments.  Does not have any head arguments.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent -compact
 \&.Bo 1 ,  \&.Bo 1 ,
 \&.Dv BUFSIZ Bc  \&.Dv BUFSIZ \&Bc
 .Ed  .Ed
 .Pp  .Pp
 See also  See also
 .Sx \&Bq .  .Sx \&Bq .
 .  
 .Ss \&Bq  .Ss \&Bq
 Encloses its arguments in square brackets.  Encloses its arguments in square brackets.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Bq 1 , \&Dv BUFSIZ
 \&.Bq 1 , Dv BUFSIZ  
 .Ed  
 .Pp  .Pp
 .Em Remarks :  .Em Remarks :
 this macro is sometimes abused to emulate optional arguments for  this macro is sometimes abused to emulate optional arguments for
Line 1017  and
Line 1348  and
 .Pp  .Pp
 See also  See also
 .Sx \&Bo .  .Sx \&Bo .
 .  
 .Ss \&Brc  .Ss \&Brc
 Closes a  Close a
 .Sx \&Bro  .Sx \&Bro
 block.  Does not have any tail arguments.  block.
 .  Does not have any tail arguments.
 .Ss \&Bro  .Ss \&Bro
 Begins a block enclosed by curly braces.  Does not have any head  Begin a block enclosed by curly braces.
 arguments.  Does not have any head arguments.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent -compact
 \&.Bro 1 , ... ,  \&.Bro 1 , ... ,
 \&.Va n Brc  \&.Va n \&Brc
 .Ed  .Ed
 .Pp  .Pp
 See also  See also
 .Sx \&Brq .  .Sx \&Brq .
 .  
 .Ss \&Brq  .Ss \&Brq
 Encloses its arguments in curly braces.  Encloses its arguments in curly braces.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Brq 1 , ... , \&Va n
 \&.Brq 1 , ... , Va n  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Bro .  .Sx \&Bro .
 .  
 .Ss \&Bsx  .Ss \&Bsx
 Format the BSD/OS version provided as an argument, or a default value if  Format the BSD/OS version provided as an argument, or a default value if
 no argument is provided.  no argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Bsx 1.0
 \&.Bsx 1.0  .D1 \&.Bsx
 \&.Bsx  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1066  See also
Line 1390  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Bt  .Ss \&Bt
 Prints  Prints
 .Dq is currently in beta test.  .Dq is currently in beta test .
 .  
 .Ss \&Bx  .Ss \&Bx
 Format the BSD version provided as an argument, or a default value if no  Format the BSD version provided as an argument, or a default value if no
 argument is provided.  argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Bx 4.4
 \&.Bx 4.4  .D1 \&.Bx
 \&.Bx  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1090  See also
Line 1410  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Cd  .Ss \&Cd
 Configuration declaration (suggested for use only in section four  Kernel configuration declaration.
 manuals).  This denotes strings accepted by  This denotes strings accepted by
 .Xr config 8 .  .Xr config 8 .
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Cd device le0 at scode?
 \&.Cd device le0 at scode?  
 .Ed  
 .Pp  .Pp
 .Em Remarks :  .Em Remarks :
 this macro is commonly abused by using quoted literals to retain  this macro is commonly abused by using quoted literals to retain
 white-space and align consecutive  whitespace and align consecutive
 .Sx \&Cd  .Sx \&Cd
 declarations.  This practise is discouraged.  declarations.
 .  This practise is discouraged.
 .Ss \&Cm  .Ss \&Cm
 Command modifiers.  Useful when specifying configuration options or  Command modifiers.
 keys.  Useful when specifying configuration options or keys.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Cm ControlPath
 \&.Cm ControlPath  .D1 \&.Cm ControlMaster
 \&.Cm ControlMaster  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Fl .  .Sx \&Fl .
 .  
 .Ss \&D1  .Ss \&D1
 One-line indented display.  This is formatted by the default rules and  One-line indented display.
 is useful for simple indented statements.  It is followed by a newline.  This is formatted by the default rules and is useful for simple indented
   statements.
   It is followed by a newline.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.D1 \&Fl abcdefgh
 \&.D1 Fl abcdefgh  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Bd  .Sx \&Bd
 and  and
 .Sx \&Dl .  .Sx \&Dl .
 .  
 .Ss \&Db  .Ss \&Db
   Switch debugging mode.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Db Cm on | off
   .Pp
   This macro is ignored by
   .Xr mandoc 1 .
 .Ss \&Dc  .Ss \&Dc
 Closes a  Close a
 .Sx \&Do  .Sx \&Do
 block.  Does not have any tail arguments.  block.
 .  Does not have any tail arguments.
 .Ss \&Dd  .Ss \&Dd
 Document date.  This is the mandatory first macro of any  Document date.
   This is the mandatory first macro of any
 .Nm  .Nm
 manual.  Its calling syntax is as follows:  manual.
   Its syntax is as follows:
 .Pp  .Pp
 .D1 \. Ns Sx \&Dd Cm date  .D1 Pf \. Sx \&Dd Op Ar date
 .Pp  .Pp
 The  The
 .Cm date  .Ar date
 field may be either  may be either
 .Ar $\&Mdocdate$ ,  .Ar $\&Mdocdate$ ,
 which signifies the current manual revision date dictated by  which signifies the current manual revision date dictated by
 .Xr cvs 1  .Xr cvs 1 ,
 or instead a valid canonical date as specified by  or instead a valid canonical date as specified by
 .Sx Dates .  .Sx Dates .
   If a date does not conform or is empty, the current date is used.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Dd $\&Mdocdate$
 \&.Dd $\&Mdocdate$  .D1 \&.Dd $\&Mdocdate: July 21 2007$
 \&.Dd $\&Mdocdate: July 21 2007$  .D1 \&.Dd July 21, 2007
 \&.Dd July 21, 2007  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Dt  .Sx \&Dt
 and  and
 .Sx \&Os .  .Sx \&Os .
 .  
 .Ss \&Dl  .Ss \&Dl
 One-line intended display.  This is formatted as literal text and is  One-line intended display.
 useful for commands and invocations.  It is followed by a newline.  This is formatted as literal text and is useful for commands and
   invocations.
   It is followed by a newline.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Dl % mandoc mdoc.7 \e(ba less
 \&.Dl % mandoc mdoc.7 | less  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Bd  .Sx \&Bd
 and  and
 .Sx \&D1 .  .Sx \&D1 .
 .  
 .Ss \&Do  .Ss \&Do
 Begins a block enclosed by double quotes.  Does not have any head  Begin a block enclosed by double quotes.
 arguments.  Does not have any head arguments.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent -compact
 \&.D1 Do April is the cruellest month Dc \e(em T.S. Eliot  \&.Do
   April is the cruellest month
   \&.Dc
   \e(em T.S. Eliot
 .Ed  .Ed
 .Pp  .Pp
 See also  See also
 .Sx \&Dq .  .Sx \&Dq .
 .  
 .Ss \&Dq  .Ss \&Dq
 Encloses its arguments in double quotes.  Encloses its arguments in
   .Dq typographic
   double-quotes.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent -compact
 \&.Dq April is the cruellest month  \&.Dq April is the cruellest month
 \e(em T.S. Eliot  \e(em T.S. Eliot
 .Ed  .Ed
 .Pp  .Pp
 See also  See also
   .Sx \&Qq ,
   .Sx \&Sq ,
   and
 .Sx \&Do .  .Sx \&Do .
 .  
 .Ss \&Dt  .Ss \&Dt
 Document title.  This is the mandatory second macro of any  Document title.
   This is the mandatory second macro of any
 .Nm  .Nm
 file.  Its calling syntax is as follows:  file.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Dt
   .Oo
   .Ar title
   .Oo
   .Ar section
   .Op Ar volume | arch
   .Oc
   .Oc
   .Ed
 .Pp  .Pp
 .D1 \. Ns Sx \&Dt Cm title section Op Cm volume | arch  
 .Pp  
 Its arguments are as follows:  Its arguments are as follows:
 .Bl -tag -width Ds -offset Ds  .Bl -tag -width Ds -offset Ds
 .It Cm title  .It Ar title
 The document's title (name).  This should be capitalised and is  The document's title (name), defaulting to
 required.  .Dq UNKNOWN
 .It Cm section  if unspecified.
 The manual section.  This may be one of  It should be capitalised.
   .It Ar section
   The manual section.
   This may be one of
 .Ar 1  .Ar 1
 .Pq utilities ,  .Pq utilities ,
 .Ar 2  .Ar 2
Line 1253  The manual section.  This may be one of
Line 1591  The manual section.  This may be one of
 or  or
 .Ar paper  .Ar paper
 .Pq paper .  .Pq paper .
 It is also required and should correspond to the manual's filename  It should correspond to the manual's filename suffix and defaults to
 suffix.  .Dq 1
 .It Cm volume  if unspecified.
   .It Ar volume
 This overrides the volume inferred from  This overrides the volume inferred from
 .Ar section .  .Ar section .
 This field is optional, and if specified, must be one of  This field is optional, and if specified, must be one of
Line 1284  This field is optional, and if specified, must be one 
Line 1623  This field is optional, and if specified, must be one 
 or  or
 .Ar CON  .Ar CON
 .Pq contributed manuals .  .Pq contributed manuals .
 .It Cm arch  .It Ar arch
 This specifies a specific relevant architecture.  If  This specifies a specific relevant architecture.
 .Cm volume  If
   .Ar volume
 is not provided, it may be used in its place, else it may be used  is not provided, it may be used in its place, else it may be used
 subsequent that.  It, too, is optional.  It must be one of  subsequent that.
   It, too, is optional.
   It must be one of
 .Ar alpha ,  .Ar alpha ,
 .Ar amd64 ,  .Ar amd64 ,
 .Ar amiga ,  .Ar amiga ,
Line 1301  subsequent that.  It, too, is optional.  It must be on
Line 1643  subsequent that.  It, too, is optional.  It must be on
 .Ar hppa64 ,  .Ar hppa64 ,
 .Ar i386 ,  .Ar i386 ,
 .Ar landisk ,  .Ar landisk ,
   .Ar loongson ,
 .Ar luna88k ,  .Ar luna88k ,
 .Ar mac68k ,  .Ar mac68k ,
 .Ar macppc ,  .Ar macppc ,
   .Ar mips64 ,
 .Ar mvme68k ,  .Ar mvme68k ,
 .Ar mvme88k ,  .Ar mvme88k ,
 .Ar mvmeppc ,  .Ar mvmeppc ,
Line 1319  or
Line 1663  or
 .El  .El
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Dt FOO 1
 \&.Dt FOO 1  .D1 \&.Dt FOO 4 KM
 \&.Dt FOO 4 KM  .D1 \&.Dt FOO 9 i386
 \&.Dt FOO 9 i386  
 \&.Dt FOO 9 KM i386  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Dd  .Sx \&Dd
 and  and
 .Sx \&Os .  .Sx \&Os .
 .  
 .Ss \&Dv  .Ss \&Dv
 Defined variables such as preprocessor constants.  Defined variables such as preprocessor constants.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Dv BUFSIZ
 \&.Dv BUFSIZ  .D1 \&.Dv STDOUT_FILENO
 \&.Dv STDOUT_FILENO  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Er .  .Sx \&Er .
 .  
 .Ss \&Dx  .Ss \&Dx
 Format the DragonFlyBSD version provided as an argument, or a default  Format the DragonFly BSD version provided as an argument, or a default
 value if no argument is provided.  value if no argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Dx 2.4.1
 \&.Dx 2.4.1  .D1 \&.Dx
 \&.Dx  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1362  See also
Line 1697  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Ec  .Ss \&Ec
   Close a scope started by
   .Sx \&Eo .
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Ec Op Ar TERM
   .Pp
   The
   .Ar TERM
   argument is used as the enclosure tail, for example, specifying \e(rq
   will emulate
   .Sx \&Dc .
 .Ss \&Ed  .Ss \&Ed
   End a display context started by
   .Sx \&Bd .
 .Ss \&Ef  .Ss \&Ef
   End a font mode context started by
   .Sx \&Bf .
 .Ss \&Ek  .Ss \&Ek
   End a keep context started by
   .Sx \&Bk .
 .Ss \&El  .Ss \&El
   End a list context started by
   .Sx \&Bl .
   .Pp
   See also
   .Sx \&Bl
   and
   .Sx \&It .
 .Ss \&Em  .Ss \&Em
 Denotes text that should be emphasised.  Note that this is a  Denotes text that should be emphasised.
 presentation term and should not be used for stylistically decorating  Note that this is a presentation term and should not be used for
 technical terms.  stylistically decorating technical terms.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Em Warnings!
 \&.Ed Warnings!  .D1 \&.Em Remarks :
 \&.Ed Remarks :  .Pp
 .Ed  See also
 .  .Sx \&Bf ,
   .Sx \&Sy ,
   and
   .Sx \&Li .
 .Ss \&En  .Ss \&En
   This macro is obsolete and not implemented in
   .Xr mandoc 1 .
 .Ss \&Eo  .Ss \&Eo
   An arbitrary enclosure.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Eo Op Ar TERM
   .Pp
   The
   .Ar TERM
   argument is used as the enclosure head, for example, specifying \e(lq
   will emulate
   .Sx \&Do .
 .Ss \&Er  .Ss \&Er
 Error constants (suggested for use only in section two manuals).  Display error constants.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Er EPERM
 \&.Er EPERM  .D1 \&.Er ENOENT
 \&.Er ENOENT  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Dv .  .Sx \&Dv .
 .  
 .Ss \&Es  .Ss \&Es
 .  This macro is obsolete and not implemented.
 .Ss \&Ev  .Ss \&Ev
 Environmental variables such as those specified in  Environmental variables such as those specified in
 .Xr environ 7 .  .Xr environ 7 .
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Ev DISPLAY
 \&.Ev DISPLAY  .D1 \&.Ev PATH
 \&.Ev PATH  
 .Ed  
 .  
 .Ss \&Ex  .Ss \&Ex
 Inserts text regarding a utility's exit values.  This macro must have  Insert a standard sentence regarding exit values.
 first the  Its syntax is as follows:
 .Fl std  .Pp
 argument specified, then an optional  .D1 Pf \. Sx \&Ex Fl std Op Ar utility
 .Ar utility .  .Pp
 If  When
 .Ar utility  .Ar utility
 is not provided, the document's name as stipulated in  is not specified, the document's name set by
 .Sx \&Nm  .Sx \&Nm
 is provided.  is used.
   .Pp
   See also
   .Sx \&Rv .
 .Ss \&Fa  .Ss \&Fa
   Function argument.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Fa
   .Op Cm argtype
   .Cm argname
   .Ed
   .Pp
   This may be invoked for names with or without the corresponding type.
   It is also used to specify the field name of a structure.
   Most often, the
   .Sx \&Fa
   macro is used in the
   .Em SYNOPSIS
   within
   .Sx \&Fo
   section 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
   .Sx \&Fa ,
   the last argument will also have a trailing comma.
   .Pp
   Examples:
   .D1 \&.Fa \(dqconst char *p\(dq
   .D1 \&.Fa \(dqint a\(dq \(dqint b\(dq \(dqint c\(dq
   .D1 \&.Fa foo
   .Pp
   See also
   .Sx \&Fo .
 .Ss \&Fc  .Ss \&Fc
   End a function context started by
   .Sx \&Fo .
 .Ss \&Fd  .Ss \&Fd
   Historically used to document include files.
   This usage has been deprecated in favour of
   .Sx \&In .
   Do not use this macro.
   .Pp
   See also
   .Sx MANUAL STRUCTURE
   and
   .Sx \&In .
 .Ss \&Fl  .Ss \&Fl
   Command-line flag.
   Used when listing arguments to command-line utilities.
   Prints a fixed-width hyphen
   .Sq \-
   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 subsequent macro
   output.
   .Pp
   Examples:
   .D1 \&.Fl a b c
   .D1 \&.Fl \&Pf a b
   .D1 \&.Fl
   .D1 \&.Op \&Fl o \&Ns \&Ar file
   .Pp
   See also
   .Sx \&Cm .
 .Ss \&Fn  .Ss \&Fn
   A function name.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Ns Sx \&Fn
   .Op Cm functype
   .Cm funcname
   .Op Oo Cm argtype Oc Cm argname
   .Ed
   .Pp
   Function arguments are surrounded in parenthesis and
   are delimited by commas.
   If no arguments are specified, blank parenthesis are output.
   .Pp
   Examples:
   .D1 \&.Fn "int funcname" "int arg0" "int arg1"
   .D1 \&.Fn funcname "int arg0"
   .D1 \&.Fn funcname arg0
   .Bd -literal -offset indent -compact
   \&.Ft functype
   \&.Fn funcname
   .Ed
   .Pp
   When referring to a function documented in another manual page, use
   .Sx \&Xr
   instead.
   See also
   .Sx MANUAL STRUCTURE
   and
   .Sx \&Ft .
 .Ss \&Fo  .Ss \&Fo
 .Ss \&Fr  Begin a function block.
   This is a multi-line version of
   .Sx \&Fn .
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Fo Cm funcname
   .Pp
   Invocations usually occur in the following context:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Ft Cm functype
   .br
   .Pf \. Sx \&Fo Cm funcname
   .br
   .Pf \. Sx \&Fa Oo Cm argtype Oc Cm argname
   .br
   \.\.\.
   .br
   .Pf \. Sx \&Fc
   .Ed
   .Pp
   A
   .Sx \&Fo
   scope is closed by
   .Pp
   See also
   .Sx MANUAL STRUCTURE ,
   .Sx \&Fa ,
   .Sx \&Fc ,
   and
   .Sx \&Ft .
 .Ss \&Ft  .Ss \&Ft
   A function type.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Ft Cm functype
   .Pp
   Examples:
   .D1 \&.Ft int
   .Bd -literal -offset indent -compact
   \&.Ft functype
   \&.Fn funcname
   .Ed
   .Pp
   See also
   .Sx MANUAL STRUCTURE ,
   .Sx \&Fn ,
   and
   .Sx \&Fo .
 .Ss \&Fx  .Ss \&Fx
 Format the FreeBSD version provided as an argument, or a default value  Format the
   .Fx
   version provided as an argument, or a default value
 if no argument is provided.  if no argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Fx 7.1
 \&.Fx 7.1  .D1 \&.Fx
 \&.Fx  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1443  See also
Line 1946  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Hf  .Ss \&Hf
   This macro is obsolete and not implemented.
 .Ss \&Ic  .Ss \&Ic
   Designate an internal or interactive command.
   This is similar to
   .Sx \&Cm
   but used for instructions rather than values.
   .Pp
   Examples:
   .D1 \&.Ic hash
   .D1 \&.Ic alias
   .Pp
   Note that using
   .Sx \&Bd Fl literal
   or
   .Sx \&D1
   is preferred for displaying code; the
   .Sx \&Ic
   macro is used when referring to specific instructions.
 .Ss \&In  .Ss \&In
   An
   .Dq include
   file.
   In the
   .Em SYNOPSIS
   section (only if invoked as the line macro), the first argument is
   preceded by
   .Dq #include ,
   the arguments is enclosed in angle brackets.
   .Pp
   Examples:
   .D1 \&.In sys/types
   .Pp
   See also
   .Sx MANUAL STRUCTURE .
 .Ss \&It  .Ss \&It
   A list item.
   The syntax of this macro depends on the list type.
   .Pp
   Lists
   of type
   .Fl hang ,
   .Fl ohang ,
   .Fl inset ,
   and
   .Fl diag
   have the following syntax:
   .Pp
   .D1 Pf \. Sx \&It Cm args
   .Pp
   Lists of type
   .Fl bullet ,
   .Fl dash ,
   .Fl enum ,
   .Fl hyphen
   and
   .Fl item
   have the following syntax:
   .Pp
   .D1 Pf \. Sx \&It
   .Pp
   with subsequent lines interpreted within the scope of the
   .Sx \&It
   until either a closing
   .Sx \&El
   or another
   .Sx \&It .
   .Pp
   The
   .Fl tag
   list has the following syntax:
   .Pp
   .D1 Pf \. Sx \&It Op Cm args
   .Pp
   Subsequent lines are interpreted as with
   .Fl bullet
   and family.
   The line arguments correspond to the list's left-hand side; body
   arguments correspond to the list's contents.
   .Pp
   The
   .Fl column
   list is the most complicated.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&It Op Cm args
   .Pp
   The
   .Cm args
   are phrases, a mix of macros and text corresponding to a line column,
   delimited by tabs or the special
   .Sq \&Ta
   pseudo-macro.
   Lines subsequent the
   .Sx \&It
   are interpreted within the scope of the last phrase.
   Calling the pseudo-macro
   .Sq \&Ta
   will open a new phrase scope (this must occur on a macro line to be
   interpreted as a macro).
   Note that the tab phrase delimiter may only be used within the
   .Sx \&It
   line itself.
   Subsequent this, only the
   .Sq \&Ta
   pseudo-macro may be used to delimit phrases.
   Furthermore, note that quoted sections propagate over tab-delimited
   phrases on an
   .Sx \&It ,
   for example,
   .Pp
   .D1 .It \(dqcol1 ; <TAB> col2 ;\(dq \&;
   .Pp
   will preserve the semicolon whitespace except for the last.
   .Pp
   See also
   .Sx \&Bl .
 .Ss \&Lb  .Ss \&Lb
   Specify a library.
   The syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Lb Cm library
   .Pp
   The
   .Cm library
   parameter may be a system library, such as
   .Cm libz
   or
   .Cm 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
   .Em SYNOPSIS
   section as described in
   .Sx MANUAL STRUCTURE .
   .Pp
   Examples:
   .D1 \&.Lb libz
   .D1 \&.Lb mdoc
 .Ss \&Li  .Ss \&Li
   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.
   .Pp
   See also
   .Sx \&Bf ,
   .Sx \&Sy ,
   and
   .Sx \&Em .
 .Ss \&Lk  .Ss \&Lk
   Format a hyperlink.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Lk Cm uri Op Cm name
   .Pp
   Examples:
   .D1 \&.Lk http://bsd.lv \*qThe BSD.lv Project\*q
   .D1 \&.Lk http://bsd.lv
   .Pp
   See also
   .Sx \&Mt .
 .Ss \&Lp  .Ss \&Lp
   Synonym for
   .Sx \&Pp .
 .Ss \&Ms  .Ss \&Ms
   Display a mathematical symbol.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Ms Cm symbol
   .Pp
   Examples:
   .D1 \&.Ms sigma
   .D1 \&.Ms aleph
 .Ss \&Mt  .Ss \&Mt
   Format a
   .Dq mailto:
   hyperlink.
   If an argument is not provided, the string
   .Dq \(ti
   is used as a default.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Mt Cm address
   .Pp
   Examples:
   .D1 \&.Mt discuss@manpages.bsd.lv
 .Ss \&Nd  .Ss \&Nd
   A one line description of the manual's content.
   This may only be invoked in the
   .Em SYNOPSIS
   section subsequent the
   .Sx \&Nm
   macro.
   .Pp
   Examples:
   .D1 \&.Sx \&Nd mdoc language reference
   .D1 \&.Sx \&Nd format and display UNIX manuals
   .Pp
   The
   .Sx \&Nd
   macro technically accepts child macros and terminates with a subsequent
   .Sx \&Sh
   invocation.
   Do not assume this behaviour: some
   .Xr whatis 1
   database generators are not smart enough to parse more than the line
   arguments and will display macros verbatim.
   .Pp
   See also
   .Sx \&Nm .
 .Ss \&Nm  .Ss \&Nm
   The name of the manual page, or \(em in particular in section 1, 6,
   and 8 pages \(em of an additional command or feature documented in
   the manual page.
   When first invoked, the
   .Sx \&Nm
   macro expects a single argument, the name of the manual page.
   Usually, the first invocation happens in the
   .Em 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
   .Sx \&Nm
   macro uses
   .Sx Block full-implicit
   semantics when invoked as the first macro on an input line in the
   .Em SYNOPSIS
   section; otherwise, it uses ordinary
   .Sx In-line
   semantics.
   .Pp
   Examples:
   .Bd -literal -offset indent
   \&.Sh SYNOPSIS
   \&.Nm cat
   \&.Op Fl benstuv
   \&.Op Ar
   .Ed
   .Pp
   In the
   .Em SYNOPSIS
   of section 2, 3 and 9 manual pages, use the
   .Sx \&Fn
   macro rather than
   .Sx \&Nm
   to mark up the name of the manual page.
 .Ss \&No  .Ss \&No
   A
   .Dq noop
   macro used to terminate prior macro contexts.
   .Pp
   Examples:
   .D1 \&.Sx \&Fl ab \&No cd \&Fl ef
 .Ss \&Ns  .Ss \&Ns
   Suppress a space.
   Following invocation, text is interpreted as free-form text until a
   macro is encountered.
   .Pp
   Examples:
   .D1 \&.Fl o \&Ns \&Ar output
   .Pp
   See also
   .Sx \&No
   and
   .Sx \&Sm .
 .Ss \&Nx  .Ss \&Nx
 Format the NetBSD version provided as an argument, or a default value if  Format the
   .Nx
   version provided as an argument, or a default value if
 no argument is provided.  no argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Nx 5.01
 \&.Nx 5.01  .D1 \&.Nx
 \&.Nx  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1477  See also
Line 2232  See also
 .Sx \&Ox ,  .Sx \&Ox ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Oc  .Ss \&Oc
   Close multi-line
   .Sx \&Oo
   context.
 .Ss \&Oo  .Ss \&Oo
   Multi-line version of
   .Sx \&Op .
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Oo
   \&.Op Fl flag Ns Ar value
   \&.Oc
   .Ed
 .Ss \&Op  .Ss \&Op
   Command-line option.
   Used when listing options to command-line utilities.
   Prints the argument(s) in brackets.
   .Pp
   Examples:
   .D1 \&.Op \&Fl a \&Ar b
   .D1 \&.Op \&Ar a | b
   .Pp
   See also
   .Sx \&Oo .
 .Ss \&Os  .Ss \&Os
 Document operating system version.  This is the mandatory third macro of  Document operating system version.
   This is the mandatory third macro of
 any  any
 .Nm  .Nm
 file.  Its calling syntax is as follows:  file.
   Its syntax is as follows:
 .Pp  .Pp
 .D1 \. Ns Sx \&Os Op Cm system  .D1 Pf \. Sx \&Os Op Cm system Op Cm version
 .Pp  .Pp
 The optional  The optional
 .Cm system  .Cm system
 parameter specifies the relevant operating system or environment.  Left  parameter specifies the relevant operating system or environment.
 unspecified, it defaults to the local operating system version.  This is  Left unspecified, it defaults to the local operating system version.
 the suggested form.  This is the suggested form.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Os
 \&.Os  .D1 \&.Os KTH/CSC/TCS
 \&.Os KTH/CSC/TCS  .D1 \&.Os BSD 4.3
 \&.Os BSD 4.3  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&Dd  .Sx \&Dd
 and  and
 .Sx \&Dt .  .Sx \&Dt .
 .  
 .Ss \&Ot  .Ss \&Ot
 Unknown usage.  Unknown usage.
 .Pp  .Pp
 .Em Remarks :  .Em Remarks :
 this macro has been deprecated.  this macro has been deprecated.
 .  
 .Ss \&Ox  .Ss \&Ox
 Format the OpenBSD version provided as an argument, or a default value  Format the
   .Ox
   version provided as an argument, or a default value
 if no argument is provided.  if no argument is provided.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Ox 4.5
 \&.Ox 4.5  .D1 \&.Ox
 \&.Ox  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1532  See also
Line 2306  See also
 .Sx \&Nx ,  .Sx \&Nx ,
 and  and
 .Sx \&Ux .  .Sx \&Ux .
 .  
 .Ss \&Pa  .Ss \&Pa
   A file-system path.
   If an argument is not provided, the string
   .Dq \(ti
   is used as a default.
   .Pp
   Examples:
   .D1 \&.Pa /usr/bin/mandoc
   .D1 \&.Pa /usr/share/man/man7/mdoc.7
   .Pp
   See also
   .Sx \&Lk .
 .Ss \&Pc  .Ss \&Pc
   Close parenthesised context opened by
   .Sx \&Po .
 .Ss \&Pf  .Ss \&Pf
   Removes the space
   .Pq Dq prefix
   between its arguments.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. \&Pf Cm prefix suffix
   .Pp
   The
   .Cm suffix
   argument may be a macro.
   .Pp
   Examples:
   .D1 \&.Pf \e. \&Sx \&Pf \&Cm prefix suffix
 .Ss \&Po  .Ss \&Po
   Multi-line version of
   .Sx \&Pq .
 .Ss \&Pp  .Ss \&Pp
   Break a paragraph.
   This will assert vertical space between prior and subsequent macros
   and/or text.
 .Ss \&Pq  .Ss \&Pq
   Parenthesised enclosure.
   .Pp
   See also
   .Sx \&Po .
 .Ss \&Qc  .Ss \&Qc
   Close quoted context opened by
   .Sx \&Qo .
 .Ss \&Ql  .Ss \&Ql
   Format a single-quoted literal.
   See also
   .Sx \&Qq
   and
   .Sx \&Sq .
 .Ss \&Qo  .Ss \&Qo
   Multi-line version of
   .Sx \&Qq .
 .Ss \&Qq  .Ss \&Qq
 .  Encloses its arguments in
   .Dq typewriter
   double-quotes.
   Consider using
   .Sx \&Dq .
   .Pp
   See also
   .Sx \&Dq ,
   .Sx \&Sq ,
   and
   .Sx \&Qo .
 .Ss \&Re  .Ss \&Re
 Closes a  Close an
 .Sx \&Rs  .Sx \&Rs
 block.  Does not have any tail arguments.  block.
 .  Does not have any tail arguments.
 .Ss \&Rs  .Ss \&Rs
 Begins a bibliographic  Begin a bibliographic
 .Pq Dq reference  .Pq Dq reference
 block.  Does not have any head arguments.  The block macro may only  block.
 contain  Does not have any head arguments.
   The block macro may only contain
 .Sx \&%A ,  .Sx \&%A ,
 .Sx \&%B ,  .Sx \&%B ,
 .Sx \&%C ,  .Sx \&%C ,
Line 1566  contain
Line 2394  contain
 .Sx \&%Q ,  .Sx \&%Q ,
 .Sx \&%R ,  .Sx \&%R ,
 .Sx \&%T ,  .Sx \&%T ,
   .Sx \&%U ,
 and  and
 .Sx \&%V  .Sx \&%V
 child macros (at least one must be specified).  child macros (at least one must be specified).
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Bd -literal -offset indent -compact
 \&.Rs  \&.Rs
 \&.%A J. E. Hopcroft  \&.%A J. E. Hopcroft
 \&.%A J. D. Ullman  \&.%A J. D. Ullman
Line 1587  If an
Line 2416  If an
 block is used within a SEE ALSO section, a vertical space is asserted  block is used within a SEE ALSO section, a vertical space is asserted
 before the rendered output, else the block continues on the current  before the rendered output, else the block continues on the current
 line.  line.
 .  
 .Ss \&Rv  .Ss \&Rv
   Inserts text regarding a function call's return value.
   This macro must consist of the
   .Fl std
   argument followed by an optional
   .Ar function .
   If
   .Ar function
   is not provided, the document's name as stipulated by the first
   .Sx \&Nm
   is provided.
   .Pp
   See also
   .Sx \&Ex .
 .Ss \&Sc  .Ss \&Sc
   Close single-quoted context opened by
   .Sx \&So .
 .Ss \&Sh  .Ss \&Sh
   Begin a new section.
   For a list of conventional manual sections, see
   .Sx MANUAL STRUCTURE .
   These sections should be used unless it's absolutely necessary that
   custom sections be used.
   .Pp
   Section names should be unique so that they may be keyed by
   .Sx \&Sx .
   .Pp
   See also
   .Sx \&Pp ,
   .Sx \&Ss ,
   and
   .Sx \&Sx .
 .Ss \&Sm  .Ss \&Sm
   Switches the spacing mode for output generated from macros.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Sm Cm on | off
   .Pp
   By default, spacing is
   .Cm on .
   When switched
   .Cm off ,
   no white space is inserted between macro arguments and between the
   output generated from adjacent macros, but free-form text lines
   still get normal spacing between words and sentences.
 .Ss \&So  .Ss \&So
   Multi-line version of
   .Sx \&Sq .
 .Ss \&Sq  .Ss \&Sq
   Encloses its arguments in
   .Dq typewriter
   single-quotes.
   .Pp
   See also
   .Sx \&Dq ,
   .Sx \&Qq ,
   and
   .Sx \&So .
 .Ss \&Ss  .Ss \&Ss
   Begin a new sub-section.
   Unlike with
   .Sx \&Sh ,
   there's no convention for sub-sections.
   Conventional sections, as described in
   .Sx MANUAL STRUCTURE ,
   rarely have sub-sections.
   .Pp
   Sub-section names should be unique so that they may be keyed by
   .Sx \&Sx .
   .Pp
   See also
   .Sx \&Pp ,
   .Sx \&Sh ,
   and
   .Sx \&Sx .
 .Ss \&St  .Ss \&St
   Replace an abbreviation for a standard with the full form.
   The following standards are recognised:
   .Pp
   .Bl -tag -width "-p1003.1g-2000X" -compact
   .It \-p1003.1-88
   .St -p1003.1-88
   .It \-p1003.1-90
   .St -p1003.1-90
   .It \-p1003.1-96
   .St -p1003.1-96
   .It \-p1003.1-2001
   .St -p1003.1-2001
   .It \-p1003.1-2004
   .St -p1003.1-2004
   .It \-p1003.1-2008
   .St -p1003.1-2008
   .It \-p1003.1
   .St -p1003.1
   .It \-p1003.1b
   .St -p1003.1b
   .It \-p1003.1b-93
   .St -p1003.1b-93
   .It \-p1003.1c-95
   .St -p1003.1c-95
   .It \-p1003.1g-2000
   .St -p1003.1g-2000
   .It \-p1003.1i-95
   .St -p1003.1i-95
   .It \-p1003.2-92
   .St -p1003.2-92
   .It \-p1003.2a-92
   .St -p1003.2a-92
   .It \-p1387.2-95
   .St -p1387.2-95
   .It \-p1003.2
   .St -p1003.2
   .It \-p1387.2
   .St -p1387.2
   .It \-isoC
   .St -isoC
   .It \-isoC-90
   .St -isoC-90
   .It \-isoC-amd1
   .St -isoC-amd1
   .It \-isoC-tcor1
   .St -isoC-tcor1
   .It \-isoC-tcor2
   .St -isoC-tcor2
   .It \-isoC-99
   .St -isoC-99
   .It \-iso9945-1-90
   .St -iso9945-1-90
   .It \-iso9945-1-96
   .St -iso9945-1-96
   .It \-iso9945-2-93
   .St -iso9945-2-93
   .It \-ansiC
   .St -ansiC
   .It \-ansiC-89
   .St -ansiC-89
   .It \-ansiC-99
   .St -ansiC-99
   .It \-ieee754
   .St -ieee754
   .It \-iso8802-3
   .St -iso8802-3
   .It \-ieee1275-94
   .St -ieee1275-94
   .It \-xpg3
   .St -xpg3
   .It \-xpg4
   .St -xpg4
   .It \-xpg4.2
   .St -xpg4.2
   .St -xpg4.3
   .It \-xbd5
   .St -xbd5
   .It \-xcu5
   .St -xcu5
   .It \-xsh5
   .St -xsh5
   .It \-xns5
   .St -xns5
   .It \-xns5.2
   .St -xns5.2
   .It \-xns5.2d2.0
   .St -xns5.2d2.0
   .It \-xcurses4.2
   .St -xcurses4.2
   .It \-susv2
   .St -susv2
   .It \-susv3
   .St -susv3
   .It \-svid4
   .St -svid4
   .El
 .Ss \&Sx  .Ss \&Sx
   Reference a section or sub-section.
   The referenced section or sub-section name must be identical to the
   enclosed argument, including whitespace.
   .Pp
   Examples:
   .D1 \&.Sx MANUAL STRUCTURE
 .Ss \&Sy  .Ss \&Sy
   Format enclosed arguments in symbolic
   .Pq Dq boldface .
   Note that this is a presentation term and should not be used for
   stylistically decorating technical terms.
   .Pp
   See also
   .Sx \&Bf ,
   .Sx \&Li ,
   and
   .Sx \&Em .
 .Ss \&Tn  .Ss \&Tn
   Format a tradename.
   .Pp
   Examples:
   .D1 \&.Tn IBM
 .Ss \&Ud  .Ss \&Ud
   Prints out
   .Dq currently under development .
 .Ss \&Ux  .Ss \&Ux
 Format the UNIX name.  Accepts no argument.  Format the UNIX name.
   Accepts no argument.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .D1 \&.Ux
 \&.Ux  
 .Ed  
 .Pp  .Pp
 See also  See also
 .Sx \&At ,  .Sx \&At ,
Line 1617  See also
Line 2630  See also
 .Sx \&Nx ,  .Sx \&Nx ,
 and  and
 .Sx \&Ox .  .Sx \&Ox .
 .  
 .Ss \&Va  .Ss \&Va
   A variable name.
   .Pp
   Examples:
   .D1 \&.Va foo
   .D1 \&.Va const char *bar ;
 .Ss \&Vt  .Ss \&Vt
   A variable type.
   This is also used for indicating global variables in the
   .Em SYNOPSIS
   section, in which case a variable name is also specified.
   Note that it accepts
   .Sx Block partial-implicit
   syntax when invoked as the first macro in the
   .Em SYNOPSIS
   section, else it accepts ordinary
   .Sx In-line
   syntax.
   .Pp
   Note that this should not be confused with
   .Sx \&Ft ,
   which is used for function return types.
   .Pp
   Examples:
   .D1 \&.Vt unsigned char
   .D1 \&.Vt extern const char * const sys_signame[] \&;
   .Pp
   See also
   .Sx MANUAL STRUCTURE
   and
   .Sx \&Va .
 .Ss \&Xc  .Ss \&Xc
   Close a scope opened by
   .Sx \&Xo .
 .Ss \&Xo  .Ss \&Xo
   Open an extension scope.
   This macro originally existed to extend the 9-argument limit of troff;
   since this limit has been lifted, the macro has been deprecated.
 .Ss \&Xr  .Ss \&Xr
   Link to another manual
   .Pq Qq cross-reference .
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Xr Cm name section
   .Pp
   The
   .Cm name
   and
   .Cm section
   are the name and section of the linked manual.
   If
   .Cm section
   is followed by non-punctuation, an
   .Sx \&Ns
   is inserted into the token stream.
   This behaviour is for compatibility with
   GNU troff.
   .Pp
   Examples:
   .D1 \&.Xr mandoc 1
   .D1 \&.Xr mandoc 1 \&;
   .D1 \&.Xr mandoc 1 \&Ns s behaviour
 .Ss \&br  .Ss \&br
   Emits a line-break.
   This macro should not be used; it is implemented for compatibility with
   historical manuals.
   .Pp
   Consider using
   .Sx \&Pp
   in the event of natural paragraph breaks.
 .Ss \&sp  .Ss \&sp
 .  Emits vertical space.
 .  This macro should not be used; it is implemented for compatibility with
   historical manuals.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&sp Op Cm height
   .Pp
   The
   .Cm height
   argument must be formatted as described in
   .Sx Scaling Widths .
   If unspecified,
   .Sx \&sp
   asserts a single vertical space.
 .Sh COMPATIBILITY  .Sh COMPATIBILITY
 This section documents compatibility with other roff implementations, at  This section documents compatibility between mandoc and other other
 this time limited to  troff implementations, at this time limited to GNU troff
 .Xr groff 1 .  .Pq Qq groff .
 The term  The term
 .Qq historic groff  .Qq historic groff
 refers to those versions before the  refers to groff versions before 1.17,
   which featured a significant update of the
 .Pa doc.tmac  .Pa doc.tmac
 file re-write  file.
 .Pq somewhere between 1.15 and 1.19 .  
 .  
 .Pp  .Pp
   Heirloom troff, the other significant troff implementation accepting
   \-mdoc, is similar to historic groff.
   .Pp
   The following problematic behaviour is found in groff:
   .ds hist (Historic groff only.)
   .Pp
 .Bl -dash -compact  .Bl -dash -compact
 .It  .It
 Negative scaling units are now truncated to zero instead of creating  Display macros
 interesting conditions, such as with  .Pq Sx \&Bd , Sx \&Dl , and Sx \&D1
 .Sq \&sp -1i .  may not be nested.
 Furthermore, the  \*[hist]
 .Sq f  
 scaling unit, while accepted, is rendered as the default unit.  
 .It  .It
 In quoted literals, groff allowed pair-wise double-quotes to produce a  .Sx \&At
 standalone double-quote in formatted output.  This idiosyncratic  with unknown arguments produces no output at all.
 behaviour is no longer applicable.  \*[hist]
   Newer groff and mandoc print
   .Qq AT&T UNIX
   and the arguments.
 .It  .It
 Display types  .Sx \&Bd Fl column
 .Sx \&Bd Fl center  does not recognize trailing punctuation characters when they immediately
 and  precede tabulator characters, but treats them as normal text and
 .Fl right  outputs a space before them.
 are aliases for  
 .Fl left .  
 The  
 .Fl file Ar file  
 argument is ignored.  Since text is not right-justified,  
 .Fl ragged  
 and  
 .Fl filled  
 are aliases, as are  
 .Fl literal  
 and  
 .Fl unfilled .  
 .It  .It
 Blocks of whitespace are stripped from both macro and free-form text  .Sx \&Bd Fl ragged compact
 lines (except when in literal mode), while groff would retain whitespace  does not start a new line.
 in free-form text lines.  \*[hist]
 .It  .It
 Historic groff has many un-callable macros.  Most of these (excluding  .Sx \&Dd
 some block-level macros) are now callable, conforming to the  without an argument prints
 non-historic groff version.  .Dq Epoch .
   In mandoc, it resolves to the current date.
 .It  .It
 The vertical bar  .Sx \&Fl
 .Sq \(ba  does not print a dash for an empty argument.
 made historic groff  \*[hist]
 .Qq go orbital  
 but is a proper delimiter in this implementation.  
 .It  .It
 .Sx \&It Fl nested  .Sx \&Fn
 is assumed for all lists (it wasn't in historic groff): any list may be  does not start a new line unless invoked as the line macro in the
 nested and  .Em SYNOPSIS
   section.
   \*[hist]
   .It
   .Sx \&Fo
   with
   .Pf non- Sx \&Fa
   children causes inconsistent spacing between arguments.
   In mandoc, a single space is always inserted between arguments.
   .It
   .Sx \&Ft
   in the
   .Em SYNOPSIS
   causes inconsistent vertical spacing, depending on whether a prior
   .Sx \&Fn
   has been invoked.
   See
   .Sx \&Ft
   and
   .Sx \&Fn
   for the normalised behaviour in mandoc.
   .It
   .Sx \&In
   ignores additional arguments and is not treated specially in the
   .Em SYNOPSIS .
   \*[hist]
   .It
   .Sx \&It
   sometimes requires a
   .Fl nested
   flag.
   \*[hist]
   In new groff and mandoc, any list may be nested by default and
 .Fl enum  .Fl enum
 lists will restart the sequence only for the sub-list.  lists will restart the sequence only for the sub-list.
 .It  .It
 Some manuals use  
 .Sx \&Li  .Sx \&Li
 incorrectly by following it with a reserved character and expecting the  followed by a reserved character is incorrectly used in some manuals
 delimiter to render.  This is not supported.  instead of properly quoting that character, which sometimes works with
   historic groff.
 .It  .It
 In groff, the  .Sx \&Lk
 .Sx \&Fo  only accepts a single link-name argument; the remainder is misformatted.
 macro only produces the first parameter.  This is no longer the case.  .It
   .Sx \&Pa
   does not format its arguments when used in the FILES section under
   certain list types.
   .It
   .Sx \&Ta
   can only be called by other macros, but not at the beginning of a line.
   .It
   .Sx \&%C
   is not implemented.
   .It
   Historic groff only allows up to eight or nine arguments per macro input
   line, depending on the exact situation.
   Providing more arguments causes garbled output.
   The number of arguments on one input line is not limited with mandoc.
   .It
   Historic groff has many un-callable macros.
   Most of these (excluding some block-level macros) are callable
   in new groff and mandoc.
   .It
   .Sq \(ba
   (vertical bar) is not fully supported as a delimiter.
   \*[hist]
   .It
   .Sq \ef
   .Pq font face
   and
   .Sq \ef
   .Pq font family face
   .Sx Text Decoration
   escapes behave irregularly when specified within line-macro scopes.
   .It
   Negative scaling units return to prior lines.
   Instead, mandoc truncates them to zero.
 .El  .El
 .  .Pp
 .  The following features are unimplemented in mandoc:
   .Pp
   .Bl -dash -compact
   .It
   .Sx \&Bd
   .Fl file Ar file .
   .It
   .Sx \&Bd
   .Fl offset Ar center
   and
   .Fl offset Ar right .
   Groff does not implement centered and flush-right rendering either,
   but produces large indentations.
   .It
   The
   .Sq \eh
   .Pq horizontal position ,
   .Sq \ev
   .Pq vertical position ,
   .Sq \em
   .Pq text colour ,
   .Sq \eM
   .Pq text filling colour ,
   .Sq \ez
   .Pq zero-length character ,
   .Sq \ew
   .Pq string length ,
   .Sq \ek
   .Pq horizontal position marker ,
   .Sq \eo
   .Pq text overstrike ,
   and
   .Sq \es
   .Pq text size
   escape sequences are all discarded in mandoc.
   .It
   The
   .Sq \ef
   scaling unit is accepted by mandoc, but rendered as the default unit.
   .It
   In quoted literals, groff allows pairwise double-quotes to produce a
   standalone double-quote in formatted output.
   This is not supported by mandoc.
   .El
 .Sh SEE ALSO  .Sh SEE ALSO
   .Xr man 1 ,
 .Xr mandoc 1 ,  .Xr mandoc 1 ,
 .Xr mandoc_char 7  .Xr mandoc_char 7
 .  .Sh HISTORY
 .  The
   .Nm
   language first appeared as a troff macro package in
   .Bx 4.4 .
   It was later significantly updated by Werner Lemberg and Ruslan Ermilov
   in groff-1.17.
   The standalone implementation that is part of the
   .Xr mandoc 1
   utility written by Kristaps Dzonsons appeared in
   .Ox 4.6 .
 .Sh AUTHORS  .Sh AUTHORS
 The  The
 .Nm  .Nm
 reference was written by  reference was written by
 .An Kristaps Dzonsons Aq kristaps@kth.se .  .An Kristaps Dzonsons Aq kristaps@bsd.lv .
 .\"  
 .\" XXX: this really isn't the place for these caveats.  
 .\" .  
 .\" .  
 .\" .Sh CAVEATS  
 .\" There are many ambiguous parts of mdoc.  
 .\" .  
 .\" .Pp  
 .\" .Bl -dash -compact  
 .\" .It  
 .\" .Sq \&Fa  
 .\" should be  
 .\" .Sq \&Va  
 .\" as function arguments are variables.  
 .\" .It  
 .\" .Sq \&Ft  
 .\" should be  
 .\" .Sq \&Vt  
 .\" as function return types are still types.  Furthermore, the  
 .\" .Sq \&Ft  
 .\" should be removed and  
 .\" .Sq \&Fo ,  
 .\" which ostensibly follows it, should follow the same convention as  
 .\" .Sq \&Va .  
 .\" .It  
 .\" .Sq \&Va  
 .\" should formalise that only one or two arguments are acceptable: a  
 .\" variable name and optional, preceding type.  
 .\" .It  
 .\" .Sq \&Fd  
 .\" is ambiguous.  It's commonly used to indicate an include file in the  
 .\" synopsis section.  
 .\" .Sq \&In  
 .\" should be used, instead.  
 .\" .It  
 .\" Only the  
 .\" .Sq \-literal  
 .\" argument to  
 .\" .Sq \&Bd  
 .\" makes sense.  The remaining ones should be removed.  
 .\" .It  
 .\" The  
 .\" .Sq \&Xo  
 .\" and  
 .\" .Sq \&Xc  
 .\" macros should be deprecated.  
 .\" .It  
 .\" The  
 .\" .Sq \&Dt  
 .\" macro lacks clarity.  It should be absolutely clear which title will  
 .\" render when formatting the manual page.  
 .\" .It  
 .\" A  
 .\" .Sq \&Lx  
 .\" should be provided for Linux (\(`a la  
 .\" .Sq \&Ox ,  
 .\" .Sq \&Nx  
 .\" etc.).  
 .\" .It  
 .\" There's no way to refer to references in  
 .\" .Sq \&Rs/Re  
 .\" blocks.  
 .\" .It  
 .\" The \-split and \-nosplit dictates via  
 .\" .Sq \&An  
 .\" are re-set when entering and leaving the AUTHORS section.  
 .\" .El  
 .\" .  
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  Added in v.1.169
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