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version 1.64, 2009/10/19 10:18:05 version 1.268, 2017/07/05 12:25:17
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 .\"     $Id$  .\"     $Id$
 .\"  .\"
 .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@kth.se>  .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   .\" Copyright (c) 2010, 2011, 2013-2017 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 semantic markup language for formatting manual pages
 .  
 .  
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm mdoc  .Nm mdoc
 language is used to format  language supports authoring of manual pages for the
 .Bx  .Xr man 1
 .Ux  utility by allowing semantic annotations of words, phrases,
 manuals.  In this reference document, we describe its syntax, structure,  page sections and complete manual pages.
 and usage.  Our reference implementation is  Such annotations are used by formatting tools to achieve a uniform
 .Xr mandoc 1 .  presentation across all manuals written in
 The  .Nm ,
   and to support hyperlinking if supported by the output medium.
   .Pp
   This reference document describes the structure of manual pages
   and the syntax and usage of the
   .Nm
   language.
   The reference implementation of a parsing and formatting tool is
   .Xr mandoc 1 ;
   the
 .Sx COMPATIBILITY  .Sx COMPATIBILITY
 section describes compatibility with  section describes compatibility with other implementations.
 .Xr groff 1 .  
 .  
 .Pp  .Pp
 An  In an
 .Nm  .Nm
 document follows simple rules:  lines beginning with the control  document, lines beginning with the control character
 character  .Sq \&.
 .Sq \.  are called
 are parsed for macros.  Other lines are interpreted within the scope of  .Dq macro lines .
 prior macros:  The first word is the macro name.
   It consists of two or three letters.
   Most macro names begin with a capital letter.
   For a list of available macros, see
   .Sx MACRO OVERVIEW .
   The words following the macro name are arguments to the macro, optionally
   including the names of other, callable macros; see
   .Sx MACRO SYNTAX
   for details.
   .Pp
   Lines not beginning with the control character are called
   .Dq text lines .
   They provide free-form text to be printed; the formatting of the text
   depends on the respective processing context:
 .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.  Text lines are interpreted within the current state.
 .Ed  .Ed
 .  
 .  
 .Sh LANGUAGE SYNTAX  
 .Nm  
 documents may contain only graphable 7-bit ASCII characters, the space  
 character, and, in certain circumstances, the tab character.  All  
 manuals must have  
 .Ux  
 line terminators.  
 .  
 .  
 .Ss Comments  
 Text following a  
 .Sq \e" ,  
 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,  
 .Sq \&.\e" ,  
 is also ignored.  Macro lines with only a control charater and optionally  
 whitespace are stripped from input.  
 .  
 .  
 .Ss Reserved Characters  
 Within a macro line, the following characters are reserved:  
 .Pp  .Pp
 .Bl -tag -width Ds -offset indent -compact  Many aspects of the basic syntax of the
 .It \&.  .Nm
 .Pq period  language are based on the
 .It \&,  .Xr roff 7
 .Pq comma  language; see the
 .It \&:  .Em LANGUAGE SYNTAX
 .Pq colon  
 .It \&;  
 .Pq semicolon  
 .It \&(  
 .Pq left-parenthesis  
 .It \&)  
 .Pq right-parenthesis  
 .It \&[  
 .Pq left-bracket  
 .It \&]  
 .Pq right-bracket  
 .It \&?  
 .Pq question  
 .It \&!  
 .Pq exclamation  
 .It \&|  
 .Pq vertical bar  
 .El  
 .  
 .Pp  
 Use of reserved characters is described in  
 .Sx MACRO SYNTAX .  
 For general use in macro lines, these characters must either be escaped  
 with a non-breaking space  
 .Pq Sq \e&  
 or, if applicable, an appropriate escape sequence used.  
 .  
 .  
 .Ss Special Characters  
 Special characters may occur in both macro and free-form lines.  
 Sequences begin with the escape character  
 .Sq \e  
 followed by either an open-parenthesis  
 .Sq \&(  
 for two-character sequences; an open-bracket  
 .Sq \&[  
 for n-character sequences (terminated at a close-bracket  
 .Sq \&] ) ;  
 or a single one-character sequence.  See  
 .Xr mandoc_char 7  
 for a complete list.  Examples include  
 .Sq \e(em  
 .Pq em-dash  
 and  and
 .Sq \ee  .Em MACRO SYNTAX
 .Pq back-slash .  sections in the
 .  .Xr roff 7
 .  manual for details, in particular regarding
 .Ss Text Decoration  comments, escape sequences, whitespace, and quoting.
 Terms may be text-decorated using the  However, using
 .Sq \ef  .Xr roff 7
 escape followed by an indicator: B (bold), I, (italic), or P and R  requests in
 (Roman, or reset).  This form is not recommended for  .Nm
 .Nm ,  documents is discouraged;
 which encourages semantic, not presentation, annotation.  .Xr mandoc 1
 .  supports some of them merely for backward compatibility.
 .  
 .Ss Predefined Strings  
 Historically,  
 .Xr groff 1  
 also defined a set of package-specific  
 .Dq predefined strings ,  
 which, like  
 .Sx Special Characters ,  
 demark special output characters and strings by way of input codes.  
 Predefined strings are escaped with the slash-asterisk,  
 .Sq \e* :  
 single-character  
 .Sq \e*X ,  
 two-character  
 .Sq \e*(XX ,  
 and N-character  
 .Sq \e*[N] .  
 See  
 .Xr mandoc_char 7  
 for a complete list.  Examples include  
 .Sq \e*(Am  
 .Pq ampersand  
 and  
 .Sq \e*(Ba  
 .Pq vertical bar .  
 .  
 .  
 .Ss Whitespace  
 In non-literal free-form lines, consecutive blocks of whitespace are  
 pruned from input and added later in the output filter, if applicable:  
 .Bd -literal -offset indent  
 These     spaces   are    pruned       from    input.  
 \&.Bd \-literal  
 These         are              not.  
 \&.Ed  
 .Ed  
 .  
 .Pp  
 In macro lines, whitespace delimits arguments and is discarded.  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  
 Macro arguments may be quoted with a double-quote to group  
 space-delimited terms or to retain blocks of whitespace.  A quoted  
 argument begins with a double-quote preceded by whitespace.  The next  
 double-quote not pair-wise adjacent to another double-quote terminates  
 the literal, regardless of surrounding whitespace.  
 .  
 .Pp  
 This produces tokens  
 .Sq a" ,  
 .Sq b c ,  
 .Sq de ,  
 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  
 \&.Em "Em a"  
 .Ed  
 .  
 .Pp  
 In free-form mode, quotes are regarded as opaque text.  
 .  
 .Ss Dates  
 TODO.  
 .  
 .Ss Scaling Widths  
 Many macros support scaled widths for their arguments, such as  
 stipulating a two-inch list indentation with the following:  
 .Bd -literal -offset indent  
 \&.Bl -tag -width 2i  
 .Ed  
 .  
 .Pp  
 The syntax for scaled widths is  
 .Sq Li [+-]?[0-9]*.[0-9]*[:unit:] ,  
 where a decimal must be preceded or proceeded by at least one digit.  
 Negative numbers, while accepted, are truncated to zero.  The following  
 scaling units are accepted:  
 .Pp  
 .Bl -tag -width Ds -offset indent -compact  
 .It c  
 centimetre  
 .It i  
 inch  
 .It P  
 pica (~1/6 inch)  
 .It p  
 point (~1/72 inch)  
 .It f  
 synonym for  
 .Sq u  
 .It v  
 default vertical span  
 .It m  
 width of rendered  
 .Sq m  
 .Pq em  
 character  
 .It n  
 width of rendered  
 .Sq n  
 .Pq en  
 character  
 .It u  
 default horizontal span  
 .It M  
 mini-em (~1/100 em)  
 .El  
 .Pp  
 Using anything other than  
 .Sq m ,  
 .Sq n ,  
 .Sq u ,  
 or  
 .Sq v  
 is necessarily non-portable across output media.  See  
 .Sx COMPATIBILITY .  
 .  
 .  
 .Sh MANUAL STRUCTURE  .Sh MANUAL STRUCTURE
 Each  A well-formed
 .Nm  .Nm
 document must begin with a document prologue, containing, in order,  document consists of a document prologue followed by one or more
   sections.
   .Pp
   The prologue, which consists of the
 .Sx \&Dd ,  .Sx \&Dd ,
 .Sx \&Dt ,  .Sx \&Dt ,
 and  and
 .Sx \&Os ,  .Sx \&Os
 then the NAME section containing at least one  macros in that order, is required for every document.
   .Pp
   The first section (sections are denoted by
   .Sx \&Sh )
   must be the NAME section, consisting of at least one
 .Sx \&Nm  .Sx \&Nm
 followed by  followed by
 .Sx \&Nd :  .Sx \&Nd .
   .Pp
   Following that, convention dictates specifying at least the
   .Em SYNOPSIS
   and
   .Em DESCRIPTION
   sections, although this varies between manual sections.
   .Pp
   The following is a well-formed skeleton
   .Nm
   file for a utility
   .Qq progname :
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Dd $\&Mdocdate$  \&.Dd $\&Mdocdate$
 \&.Dt mdoc 7  \&.Dt PROGNAME section
 \&.Os  \&.Os
 \&.  
 \&.Sh NAME  \&.Sh NAME
 \&.Nm foo  \&.Nm progname
 \&.Nd a description goes here  \&.Nd one line about what it does
 \&.\e\*q The next is for sections 2 & 3 only.  \&.\e\(dq .Sh LIBRARY
 \&.\e\*q .Sh LIBRARY  \&.\e\(dq For sections 2, 3, and 9 only.
 \&.  \&.\e\(dq Not used in OpenBSD.
 \&.Sh SYNOPSIS  \&.Sh SYNOPSIS
 \&.Nm foo  \&.Nm progname
 \&.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\(dq .Sh CONTEXT
 \&.\e\*q The next is for sections 1 & 8 only.  \&.\e\(dq For section 9 functions only.
 \&.\e\*q .Sh EXIT STATUS  \&.\e\(dq .Sh IMPLEMENTATION NOTES
 \&.\e\*q The next is for sections 2, 3, & 9 only.  \&.\e\(dq Not used in OpenBSD.
 \&.\e\*q .Sh RETURN VALUES  \&.\e\(dq .Sh RETURN VALUES
 \&.\e\*q The next is for sections 1, 6, 7, & 8 only.  \&.\e\(dq For sections 2, 3, and 9 function return values only.
 \&.\e\*q .Sh ENVIRONMENT  \&.\e\(dq .Sh ENVIRONMENT
 \&.\e\*q .Sh FILES  \&.\e\(dq For sections 1, 6, 7, and 8 only.
 \&.\e\*q .Sh EXAMPLES  \&.\e\(dq .Sh FILES
 \&.\e\*q The next is for sections 1, 4, 6, 7, & 8 only.  \&.\e\(dq .Sh EXIT STATUS
 \&.\e\*q .Sh DIAGNOSTICS  \&.\e\(dq For sections 1, 6, and 8 only.
 \&.\e\*q The next is for sections 2, 3, & 9 only.  \&.\e\(dq .Sh EXAMPLES
 \&.\e\*q .Sh ERRORS  \&.\e\(dq .Sh DIAGNOSTICS
 \&.\e\*q .Sh SEE ALSO  \&.\e\(dq For sections 1, 4, 6, 7, 8, and 9 printf/stderr messages only.
 \&.\e\*q .Xr foobar 1  \&.\e\(dq .Sh ERRORS
 \&.\e\*q .Sh STANDARDS  \&.\e\(dq For sections 2, 3, 4, and 9 errno settings only.
 \&.\e\*q .Sh HISTORY  \&.\e\(dq .Sh SEE ALSO
 \&.\e\*q .Sh AUTHORS  \&.\e\(dq .Xr foobar 1
 \&.\e\*q .Sh CAVEATS  \&.\e\(dq .Sh STANDARDS
 \&.\e\*q .Sh BUGS  \&.\e\(dq .Sh HISTORY
 \&.\e\*q .Sh SECURITY CONSIDERATIONS  \&.\e\(dq .Sh AUTHORS
   \&.\e\(dq .Sh CAVEATS
   \&.\e\(dq .Sh BUGS
   \&.\e\(dq .Sh SECURITY CONSIDERATIONS
   \&.\e\(dq Not used in OpenBSD.
 .Ed  .Ed
 .  
 .Pp  .Pp
 Subsequent SYNOPSIS and DESCRIPTION sections are strongly encouraged,  The sections in an
 but non-compulsory.  .Nm
 .  document are conventionally ordered as they appear above.
 .  Sections should be composed as follows:
 .Sh MACRO SYNTAX  .Bl -ohang -offset Ds
 Macros are one to three three characters in length and begin with a  .It Em NAME
 control character ,  The name(s) and a one line description of the documented material.
 .Sq \&. ,  The syntax for this as follows:
 at the beginning of the line.  An arbitrary amount of whitespace may  
 sit between the control character and the macro name.  Thus, the  
 following are equivalent:  
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Pp  \&.Nm name0 ,
 \&.\ \ \ \&Pp  \&.Nm name1 ,
   \&.Nm name2
   \&.Nd a one line description
 .Ed  .Ed
 .  
 .Pp  .Pp
 The syntax of a macro depends on its classification.  In this section,  Multiple
 .Sq \-arg  .Sq \&Nm
 refers to macro arguments, which may be followed by zero or more  names should be separated by commas.
 .Sq parm  
 parameters;  
 .Sq \&Yo  
 opens the scope of a macro; and if specified,  
 .Sq \&Yc  
 closes it out.  
 .  
 .Pp  .Pp
 The  The
 .Em Callable  .Sx \&Nm
 column indicates that the macro may be called subsequent to the initial  macro(s) must precede the
 line-macro.  If a macro is not callable, then its invocation after the  .Sx \&Nd
 initial line macro is interpreted as opaque text, such that  macro.
 .Sq \&.Fl \&Sh  
 produces  
 .Sq Fl \&Sh .  
 .  
 .Pp  .Pp
 The  See
 .Em Parsable  .Sx \&Nm
 column indicates whether the macro may be followed by further  and
 (ostensibly callable) macros.  If a macro is not parsable, subsequent  .Sx \&Nd .
 macro invocations on the line will be interpreted as opaque text.  .It Em LIBRARY
 .  The name of the library containing the documented material, which is
   assumed to be a function in a section 2, 3, or 9 manual.
   The syntax for this is as follows:
   .Bd -literal -offset indent
   \&.Lb libarm
   .Ed
 .Pp  .Pp
 The  See
 .Em Scope  .Sx \&Lb .
 column, if applicable, describes closure rules.  .It Em SYNOPSIS
 .  Documents the utility invocation syntax, function call syntax, or device
 .  configuration.
 .Ss Block full-explicit  .Pp
 Multi-line scope closed by an explicit closing macro.  All macros  For the first, utilities (sections 1, 6, and 8), this is
 contains bodies; only  generally structured as follows:
 .Sx \&Bf  
 contains a head.  
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB  \&.Nm bar
 \(lBbody...\(rB  \&.Op Fl v
 \&.Yc  \&.Op Fl o Ar file
   \&.Op Ar
   \&.Nm foo
   \&.Op Fl v
   \&.Op Fl o Ar file
   \&.Op Ar
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXX"  Commands should be ordered alphabetically.
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .Pp
 .It Sx \&Bd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ed  For the second, function calls (sections 2, 3, 9):
 .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 \&Bl  Ta    \&No     Ta    \&No     Ta    closed by Sx \&El  
 .It Sx \&Ed  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bd  
 .It Sx \&Ef  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bf  
 .It Sx \&Ek  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bk  
 .It Sx \&El  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bl  
 .El  
 .  
 .  
 .Ss Block full-implicit  
 Multi-line scope closed by end-of-file or implicitly by another macro.  
 All macros have bodies; some  
 .Po  
 .Sx \&It Fl bullet ,  
 .Fl hyphen ,  
 .Fl dash ,  
 .Fl enum ,  
 .Fl item  
 .Pc  
 don't have heads; only one  
 .Po  
 .Sx \&It Fl column  
 .Pc  
 has multiple heads.  
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB  \&.In header.h
 \(lBbody...\(rB  \&.Vt extern const char *global;
   \&.Ft "char *"
   \&.Fn foo "const char *src"
   \&.Ft "char *"
   \&.Fn bar "const char *src"
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXXXXXXXXXX"  Ordering of
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .Sx \&In ,
 .It Sx \&It  Ta    \&No     Ta    Yes      Ta    closed by Sx \&It , Sx \&El  .Sx \&Vt ,
 .It Sx \&Nd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh  .Sx \&Fn ,
 .It Sx \&Sh  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh  and
 .It Sx \&Ss  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh , Sx \&Ss  .Sx \&Fo
 .El  macros should follow C header-file conventions.
 .  .Pp
 .  And for the third, configurations (section 4):
 .Ss Block partial-explicit  
 Like block full-explicit, but also with single-line scope.  Each  
 has at least a body and, in limited circumstances, a head  
 .Po  
 .Sx \&Fo ,  
 .Sx \&Eo  
 .Pc  
 and/or tail  
 .Pq Sx \&Ec .  
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB  \&.Cd \(dqit* at isa? port 0x2e\(dq
 \(lBbody...\(rB  \&.Cd \(dqit* at isa? port 0x4e\(dq
 \&.Yc \(lBtail...\(rB  
   
 \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB \  
 \(lBbody...\(rB \&Yc \(lBtail...\(rB  
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset indent  Manuals not in these sections generally don't need a
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .Em SYNOPSIS .
 .It Sx \&Ac  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Ao  .Pp
 .It Sx \&Ao  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ac  Some macros are displayed differently in the
 .It Sx \&Bc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Bo  .Em SYNOPSIS
 .It Sx \&Bo  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bc  section, particularly
 .It Sx \&Brc Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bro  .Sx \&Nm ,
 .It Sx \&Bro Ta    Yes      Ta    Yes      Ta    closed by Sx \&Brc  .Sx \&Cd ,
 .It Sx \&Dc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Do  .Sx \&Fd ,
 .It Sx \&Do  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Dc  .Sx \&Fn ,
 .It Sx \&Ec  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Eo  .Sx \&Fo ,
 .It Sx \&Eo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ec  .Sx \&In ,
 .It Sx \&Fc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Fo  .Sx \&Vt ,
 .It Sx \&Fo  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Fc  and
 .It Sx \&Oc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Oo  .Sx \&Ft .
 .It Sx \&Oo  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Oc  All of these macros are output on their own line.
 .It Sx \&Pc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Po  If two such dissimilar macros are pairwise invoked (except for
 .It Sx \&Po  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Pc  .Sx \&Ft
 .It Sx \&Qc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Oo  before
 .It Sx \&Qo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Oc  .Sx \&Fo
 .It Sx \&Re  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Rs  or
 .It Sx \&Rs  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Re  .Sx \&Fn ) ,
 .It Sx \&Sc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&So  they are separated by a vertical space, unless in the case of
 .It Sx \&So  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Sc  .Sx \&Fo ,
 .It Sx \&Xc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Xo  .Sx \&Fn ,
 .It Sx \&Xo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Xc  and
 .El  .Sx \&Ft ,
 .  which are always separated by vertical space.
 .  .Pp
 .Ss Block partial-implicit  When text and macros following an
 Like block full-implicit, but with single-line scope closed by  .Sx \&Nm
 .Sx Reserved Characters  macro starting an input line span multiple output lines,
 or end of line.  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 begins with an expansion of the brief, one line description in
   .Em NAME :
 .Bd -literal -offset indent  .Bd -literal -offset indent
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB  The
   \&.Nm
   utility does this, that, and the other.
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset indent  It usually follows with a breakdown of the options (if documenting a
 .It Em Macro Ta Em Callable Ta Em Parsable  command), such as:
 .It Sx \&Aq  Ta    Yes      Ta    Yes  
 .It Sx \&Bq  Ta    Yes      Ta    Yes  
 .It Sx \&Brq Ta    Yes      Ta    Yes  
 .It Sx \&D1  Ta    \&No     Ta    \&Yes  
 .It Sx \&Dl  Ta    \&No     Ta    Yes  
 .It Sx \&Dq  Ta    Yes      Ta    Yes  
 .It Sx \&Op  Ta    Yes      Ta    Yes  
 .It Sx \&Pq  Ta    Yes      Ta    Yes  
 .It Sx \&Ql  Ta    Yes      Ta    Yes  
 .It Sx \&Qq  Ta    Yes      Ta    Yes  
 .It Sx \&Sq  Ta    Yes      Ta    Yes  
 .El  
 .  
 .  
 .Ss In-line  
 Closed by  
 .Sx Reserved Characters ,  
 end of line, fixed argument lengths, and/or subsequent macros.  In-line  
 macros have only text children.  If a number (or inequality) of  
 arguments is  
 .Pq n ,  
 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  The arguments are as follows:
   \&.Bl \-tag \-width Ds
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB Yc...  \&.It Fl v
   Print verbose information.
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN  \&.El
 .Ed  .Ed
 .  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset indent  List the options in alphabetical order,
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments  uppercase before lowercase for each letter and
 .It Sx \&%A  Ta    \&No     Ta    \&No     Ta    >0  with no regard to whether an option takes an argument.
 .It Sx \&%B  Ta    \&No     Ta    \&No     Ta    >0  Put digits in ascending order before all letter options.
 .It Sx \&%C  Ta    \&No     Ta    \&No     Ta    >0  .Pp
 .It Sx \&%D  Ta    \&No     Ta    \&No     Ta    >0  Manuals not documenting a command won't include the above fragment.
 .It Sx \&%I  Ta    \&No     Ta    \&No     Ta    >0  .Pp
 .It Sx \&%J  Ta    \&No     Ta    \&No     Ta    >0  Since the
 .It Sx \&%N  Ta    \&No     Ta    \&No     Ta    >0  .Em DESCRIPTION
 .It Sx \&%O  Ta    \&No     Ta    \&No     Ta    >0  section usually contains most of the text of a manual, longer manuals
 .It Sx \&%P  Ta    \&No     Ta    \&No     Ta    >0  often use the
 .It Sx \&%R  Ta    \&No     Ta    \&No     Ta    >0  .Sx \&Ss
 .It Sx \&%T  Ta    \&No     Ta    \&No     Ta    >0  macro to form subsections.
 .It Sx \&%V  Ta    \&No     Ta    \&No     Ta    >0  In very long manuals, the
 .It Sx \&Ad  Ta    Yes      Ta    Yes      Ta    n  .Em DESCRIPTION
 .It Sx \&An  Ta    Yes      Ta    Yes      Ta    n  may be split into multiple sections, each started by an
 .It Sx \&Ap  Ta    Yes      Ta    Yes      Ta    0  .Sx \&Sh
 .It Sx \&Ar  Ta    Yes      Ta    Yes      Ta    n  macro followed by a non-standard section name, and each having
 .It Sx \&At  Ta    Yes      Ta    Yes      Ta    1  several subsections, like in the present
 .It Sx \&Bsx Ta    Yes      Ta    Yes      Ta    n  .Nm
 .It Sx \&Bt  Ta    \&No     Ta    \&No     Ta    0  manual.
 .It Sx \&Bx  Ta    Yes      Ta    Yes      Ta    n  .It Em CONTEXT
 .It Sx \&Cd  Ta    Yes      Ta    Yes      Ta    >0  This section lists the contexts in which functions can be called in section 9.
 .It Sx \&Cm  Ta    Yes      Ta    Yes      Ta    n  The contexts are autoconf, process, or interrupt.
 .It Sx \&Db  Ta    \&No     Ta    \&No     Ta    1  .It Em IMPLEMENTATION NOTES
 .It Sx \&Dd  Ta    \&No     Ta    \&No     Ta    >0  Implementation-specific notes should be kept here.
 .It Sx \&Dt  Ta    \&No     Ta    \&No     Ta    n  This is useful when implementing standard functions that may have side
 .It Sx \&Dv  Ta    Yes      Ta    Yes      Ta    n  effects or notable algorithmic implications.
 .It Sx \&Dx  Ta    Yes      Ta    Yes      Ta    n  .It Em RETURN VALUES
 .It Sx \&Em  Ta    Yes      Ta    Yes      Ta    >0  This section documents the
 .It Sx \&En  Ta    \&No     Ta    \&No     Ta    0  return values of functions in sections 2, 3, and 9.
 .It Sx \&Er  Ta    Yes      Ta    Yes      Ta    >0  .Pp
 .It Sx \&Es  Ta    \&No     Ta    \&No     Ta    0  See
 .It Sx \&Ev  Ta    Yes      Ta    Yes      Ta    n  .Sx \&Rv .
 .It Sx \&Ex  Ta    \&No     Ta    \&No     Ta    n  .It Em ENVIRONMENT
 .It Sx \&Fa  Ta    Yes      Ta    Yes      Ta    n  Lists the environment variables used by the utility,
 .It Sx \&Fd  Ta    \&No     Ta    \&No     Ta    >0  and explains the syntax and semantics of their values.
 .It Sx \&Fl  Ta    Yes      Ta    Yes      Ta    n  The
 .It Sx \&Fn  Ta    Yes      Ta    Yes      Ta    >0  .Xr environ 7
 .It Sx \&Fr  Ta    \&No     Ta    \&No     Ta    n  manual provides examples of typical content and formatting.
 .It Sx \&Ft  Ta    Yes      Ta    Yes      Ta    n  .Pp
 .It Sx \&Fx  Ta    Yes      Ta    Yes      Ta    n  See
 .It Sx \&Hf  Ta    \&No     Ta    \&No     Ta    n  .Sx \&Ev .
 .It Sx \&Ic  Ta    Yes      Ta    Yes      Ta    >0  .It Em FILES
 .It Sx \&In  Ta    \&No     Ta    \&No     Ta    n  Documents files used.
 .It Sx \&Lb  Ta    \&No     Ta    \&No     Ta    1  It's helpful to document both the file name and a short description of how
 .It Sx \&Li  Ta    Yes      Ta    Yes      Ta    n  the file is used (created, modified, etc.).
 .It Sx \&Lk  Ta    Yes      Ta    Yes      Ta    n  .Pp
 .It Sx \&Lp  Ta    \&No     Ta    \&No     Ta    0  See
 .It Sx \&Ms  Ta    Yes      Ta    Yes      Ta    >0  .Sx \&Pa .
 .It Sx \&Mt  Ta    Yes      Ta    Yes      Ta    >0  .It Em EXIT STATUS
 .It Sx \&Nm  Ta    Yes      Ta    Yes      Ta    n  This section documents the
 .It Sx \&No  Ta    Yes      Ta    Yes      Ta    0  command exit status for section 1, 6, and 8 utilities.
 .It Sx \&Ns  Ta    Yes      Ta    Yes      Ta    0  Historically, this information was described in
 .It Sx \&Nx  Ta    Yes      Ta    Yes      Ta    n  .Em DIAGNOSTICS ,
 .It Sx \&Os  Ta    \&No     Ta    \&No     Ta    n  a practise that is now discouraged.
 .It Sx \&Ot  Ta    \&No     Ta    \&No     Ta    n  .Pp
 .It Sx \&Ox  Ta    Yes      Ta    Yes      Ta    n  See
 .It Sx \&Pa  Ta    Yes      Ta    Yes      Ta    n  .Sx \&Ex .
 .It Sx \&Pf  Ta    \&No     Ta    Yes      Ta    1  .It Em EXAMPLES
 .It Sx \&Pp  Ta    \&No     Ta    \&No     Ta    0  Example usages.
 .It Sx \&Rv  Ta    \&No     Ta    \&No     Ta    n  This often contains snippets of well-formed, well-tested invocations.
 .It Sx \&Sm  Ta    \&No     Ta    \&No     Ta    1  Make sure that examples work properly!
 .It Sx \&St  Ta    \&No     Ta    Yes      Ta    1  .It Em DIAGNOSTICS
 .It Sx \&Sx  Ta    Yes      Ta    Yes      Ta    >0  Documents error messages.
 .It Sx \&Sy  Ta    Yes      Ta    Yes      Ta    >0  In section 4 and 9 manuals, these are usually messages printed by the
 .It Sx \&Tn  Ta    Yes      Ta    Yes      Ta    >0  kernel to the console and to the kernel log.
 .It Sx \&Ud  Ta    \&No     Ta    \&No     Ta    0  In section 1, 6, 7, and 8, these are usually messages printed by
 .It Sx \&Ux  Ta    Yes      Ta    Yes      Ta    n  userland programs to the standard error output.
 .It Sx \&Va  Ta    Yes      Ta    Yes      Ta    n  .Pp
 .It Sx \&Vt  Ta    Yes      Ta    Yes      Ta    >0  Historically, this section was used in place of
 .It Sx \&Xr  Ta    Yes      Ta    Yes      Ta    >0, <3  .Em EXIT STATUS
 .It Sx \&br  Ta    \&No     Ta    \&No     Ta    0  for manuals in sections 1, 6, and 8; however, this practise is
 .It Sx \&sp  Ta    \&No     Ta    \&No     Ta    1  discouraged.
 .El  .Pp
 .  See
 .  .Sx \&Bl
 .Sh REFERENCE  .Fl diag .
   .It Em ERRORS
   Documents
   .Xr errno 2
   settings in sections 2, 3, 4, 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 (ignoring case).
   .Pp
   References to other documentation concerning the topic of the manual page,
   for example authoritative books or journal articles, may also be
   provided in this section.
   .Pp
   See
   .Sx \&Rs
   and
   .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 it was first implemented,
   and when it was ported to or reimplemented for the operating system at hand.
   .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
   .Sh MACRO OVERVIEW
   This overview is sorted such that macros of similar purpose are listed
   together, to help find the best macro for any given purpose.
   Deprecated macros are not included in the overview, but can be found below
   in the alphabetical
   .Sx MACRO REFERENCE .
   .Ss Document preamble and NAME section macros
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Dd Ta document date: Cm $\&Mdocdate$ | Ar month day , year
   .It Sx \&Dt Ta document title: Ar TITLE section Op Ar arch
   .It Sx \&Os Ta operating system version: Op Ar system Op Ar version
   .It Sx \&Nm Ta document name (one argument)
   .It Sx \&Nd Ta document description (one line)
   .El
   .Ss Sections and cross references
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Sh Ta section header (one line)
   .It Sx \&Ss Ta subsection header (one line)
   .It Sx \&Sx Ta internal cross reference to a section or subsection
   .It Sx \&Xr Ta cross reference to another manual page: Ar name section
   .It Sx \&Pp , \&Lp Ta start a text paragraph (no arguments)
   .El
   .Ss Displays and lists
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Bd , \&Ed Ta display block:
   .Fl Ar type
   .Op Fl offset Ar width
   .Op Fl compact
   .It Sx \&D1 Ta indented display (one line)
   .It Sx \&Dl Ta indented literal display (one line)
   .It Sx \&Ql Ta in-line literal display: Ql text
   .It Sx \&Bl , \&El Ta list block:
   .Fl Ar type
   .Op Fl width Ar val
   .Op Fl offset Ar val
   .Op Fl compact
   .It Sx \&It Ta list item (syntax depends on Fl Ar type )
   .It Sx \&Ta Ta table cell separator in Sx \&Bl Fl column No lists
   .It Sx \&Rs , \&%* , \&Re Ta bibliographic block (references)
   .El
   .Ss Spacing control
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Pf Ta prefix, no following horizontal space (one argument)
   .It Sx \&Ns Ta roman font, no preceding horizontal space (no arguments)
   .It Sx \&Ap Ta apostrophe without surrounding whitespace (no arguments)
   .It Sx \&Sm Ta switch horizontal spacing mode: Op Cm on | off
   .It Sx \&Bk , \&Ek Ta keep block: Fl words
   .El
   .Ss Semantic markup for command line utilities
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Nm Ta start a SYNOPSIS block with the name of a utility
   .It Sx \&Fl Ta command line options (flags) (>=0 arguments)
   .It Sx \&Cm Ta command modifier (>0 arguments)
   .It Sx \&Ar Ta command arguments (>=0 arguments)
   .It Sx \&Op , \&Oo , \&Oc Ta optional syntax elements (enclosure)
   .It Sx \&Ic Ta internal or interactive command (>0 arguments)
   .It Sx \&Ev Ta environmental variable (>0 arguments)
   .It Sx \&Pa Ta file system path (>=0 arguments)
   .El
   .Ss Semantic markup for function libraries
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Lb Ta function library (one argument)
   .It Sx \&In Ta include file (one argument)
   .It Sx \&Fd Ta other preprocessor directive (>0 arguments)
   .It Sx \&Ft Ta function type (>0 arguments)
   .It Sx \&Fo , \&Fc Ta function block: Ar funcname
   .It Sx \&Fn Ta function name:
   .Op Ar functype
   .Ar funcname
   .Oo
   .Op Ar argtype
   .Ar argname
   .Oc
   .It Sx \&Fa Ta function argument (>0 arguments)
   .It Sx \&Vt Ta variable type (>0 arguments)
   .It Sx \&Va Ta variable name (>0 arguments)
   .It Sx \&Dv Ta defined variable or preprocessor constant (>0 arguments)
   .It Sx \&Er Ta error constant (>0 arguments)
   .It Sx \&Ev Ta environmental variable (>0 arguments)
   .El
   .Ss Various semantic markup
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&An Ta author name (>0 arguments)
   .It Sx \&Lk Ta hyperlink: Ar uri Op Ar name
   .It Sx \&Mt Ta Do mailto Dc hyperlink: Ar address
   .It Sx \&Cd Ta kernel configuration declaration (>0 arguments)
   .It Sx \&Ad Ta memory address (>0 arguments)
   .It Sx \&Ms Ta mathematical symbol (>0 arguments)
   .El
   .Ss Physical markup
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Em Ta italic font or underline (emphasis) (>0 arguments)
   .It Sx \&Sy Ta boldface font (symbolic) (>0 arguments)
   .It Sx \&Li Ta typewriter font (literal) (>0 arguments)
   .It Sx \&No Ta return to roman font (normal) (no arguments)
   .It Sx \&Bf , \&Ef Ta font block:
   .Op Fl Ar type | Cm \&Em | \&Li | \&Sy
   .El
   .Ss Physical enclosures
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Dq , \&Do , \&Dc Ta enclose in typographic double quotes: Dq text
   .It Sx \&Qq , \&Qo , \&Qc Ta enclose in typewriter double quotes: Qq text
   .It Sx \&Sq , \&So , \&Sc Ta enclose in single quotes: Sq text
   .It Sx \&Pq , \&Po , \&Pc Ta enclose in parentheses: Pq text
   .It Sx \&Bq , \&Bo , \&Bc Ta enclose in square brackets: Bq text
   .It Sx \&Brq , \&Bro , \&Brc Ta enclose in curly braces: Brq text
   .It Sx \&Aq , \&Ao , \&Ac Ta enclose in angle brackets: Aq text
   .It Sx \&Eo , \&Ec Ta generic enclosure
   .El
   .Ss Text production
   .Bl -column "Brq, Bro, Brc" description
   .It Sx \&Ex Fl std Ta standard command exit values: Op Ar utility ...
   .It Sx \&Rv Fl std Ta standard function return values: Op Ar function ...
   .It Sx \&St Ta reference to a standards document (one argument)
   .It Sx \&At Ta At
   .It Sx \&Bx Ta Bx
   .It Sx \&Bsx Ta Bsx
   .It Sx \&Nx Ta Nx
   .It Sx \&Fx Ta Fx
   .It Sx \&Ox Ta Ox
   .It Sx \&Dx Ta Dx
   .El
   .Sh MACRO 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.  line.
 .Pp  
 Author names should be ordered with full or abbreviated forename(s)  Author names should be ordered with full or abbreviated forename(s)
 first, then full surname.  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 Compatibility remark :  
 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 canonical syntax for  block.
 .Sx Dates .  Recommended formats of arguments are
 .  .Ar month day , year
   or just
   .Ar 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
   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  .Dl \&.Ad [0,$]
 \&.Ad [0,$]  .Dl \&.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:  Can be used both for the authors of the program, function, or driver
 .Bl -tag -width 12n -offset indent  documented in the manual, or for the authors of the manual itself.
   Requires either the name of an author or one of the following arguments:
   .Pp
   .Bl -tag -width "-nosplitX" -offset indent -compact
 .It Fl split  .It Fl split
 Renders a line break is rendered 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  .Dl \&.An -nosplit
 \&.An -nosplit  .Dl \&.An Kristaps Dzonsons \&Aq \&Mt 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  .Dl \&.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  .Dl \&.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  .Dl \&.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 768  statements, which should use
Line 705  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 strings  Command arguments.
 .Dq file ...  If an argument is not provided, the string
 are used as a default.  .Dq file ...\&
   is used as a default.
 .Pp  .Pp
 Examples:  Examples:
 .Bd -literal -offset indent  .Dl ".Fl o Ar file"
 \&.Fl o Ns Ar file1  .Dl ".Ar"
 \&.Ar  .Dl ".Ar arg1 , arg2 ."
 \&.Ar arg1 , arg2 .  .Pp
 .Ed  The arguments to the
 .  .Sx \&Ar
   macro are names and placeholders for command arguments;
   for fixed strings to be passed verbatim as arguments, use
   .Sx \&Fl
   or
   .Sx \&Cm .
 .Ss \&At  .Ss \&At
 Formats an AT&T version.  Accepts at most one parameter:  Formats an
 .Bl -tag -width 12n -offset indent  .At
   version.
   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 III
 A system version of  .At III .
 .At .  .It Cm V | V.[1-4]
   A version of
   .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  .Dl \&.At
 \&.At  .Dl \&.At III
 \&.At V.1  .Dl \&.At V.1
 .Ed  .Pp
 .  See also
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
 .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 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
   Produce one output line from each input line, and center-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.  Change the positions of line breaks to fill each line, and left- and
   right-justify the resulting block.
 .It Fl literal  .It Fl literal
 Alias for  Produce one output line from each input line,
 .Fl unfilled .  and do not justify the block at all.
 .It Fl centered  Preserve white space as it appears in the input.
 Centre-justify each line.  Always use a constant-width font.
   Use this for displaying source code.
   .It Fl ragged
   Change the positions of line breaks to fill each line, and left-justify
   the resulting block.
   .It Fl unfilled
   The same as
   .Fl literal ,
   but using the same font as for normal text, which is a variable width font
   if supported by the output device.
 .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 a standard indentation (six constant width characters);
 .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 center 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.
 .Ar Ds ,  The most popular is the imaginary macro
   .Ar \&Ds ,
 which resolves to  which resolves to
 .Ar 6n .  .Sy 6n .
 .It  .It
 As a scaling unit following the syntax described in  A scaling width as described in
 .Sx Scaling Widths .  .Xr roff 7 .
 .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 \-literal \-offset indent  \&.Bd \-literal \-offset indent \-compact
 int     Hello       world.
 main(void)  
 {  
         printf("Hello, world!\en");  
 }  
 \&.Ed  \&.Ed
   
 \&.Bd \-unfilled \-offset two-indent \-compact  
 Hello  
       world.  
 \&.Ed  
 .Ed  .Ed
 .  .Pp
   See also
   .Sx \&D1
   and
   .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
   For each macro, keep its output together on the same output line,
   until the end of the macro or the end of the input line is reached,
   whichever comes first.
   Line breaks in text lines are unaffected.
   The syntax is as 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 specified using 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 macro names as described for
   .Sx \&Bd
   .Fl offset ,
   scaling widths as described in
   .Xr roff 7 ,
   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, the string length of each argument
   specifies the width of one column.
   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.
   Most often used in the
   .Em DIAGNOSTICS
   section with error constants in the item heads.
   .It Fl enum
   A numbered list.
   No item heads can be specified.
   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
   Lists may be nested within lists and displays.
   Nesting of
   .Fl column
   and
   .Fl enum
   lists may not be portable.
   .Pp
   See also
   .Sx \&El
   and
   .Sx \&It .
 .Ss \&Bo  .Ss \&Bo
   Begin a block enclosed by square brackets.
   Does not have any head arguments.
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Bo 1 ,
   \&.Dv BUFSIZ \&Bc
   .Ed
   .Pp
   See also
   .Sx \&Bq .
 .Ss \&Bq  .Ss \&Bq
   Encloses its arguments in square brackets.
   .Pp
   Examples:
   .Dl \&.Bq 1 , \&Dv BUFSIZ
   .Pp
   .Em Remarks :
   this macro is sometimes abused to emulate optional arguments for
   commands; the correct macros to use for this purpose are
   .Sx \&Op ,
   .Sx \&Oo ,
   and
   .Sx \&Oc .
   .Pp
   See also
   .Sx \&Bo .
 .Ss \&Brc  .Ss \&Brc
   Close a
   .Sx \&Bro
   block.
   Does not have any tail arguments.
 .Ss \&Bro  .Ss \&Bro
   Begin a block enclosed by curly braces.
   Does not have any head arguments.
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Bro 1 , ... ,
   \&.Va n \&Brc
   .Ed
   .Pp
   See also
   .Sx \&Brq .
 .Ss \&Brq  .Ss \&Brq
   Encloses its arguments in curly braces.
   .Pp
   Examples:
   .Dl \&.Brq 1 , ... , \&Va n
   .Pp
   See also
   .Sx \&Bro .
 .Ss \&Bsx  .Ss \&Bsx
   Format the
   .Bsx
   version provided as an argument, or a default value if
   no argument is provided.
   .Pp
   Examples:
   .Dl \&.Bsx 1.0
   .Dl \&.Bsx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
 .Ss \&Bt  .Ss \&Bt
   Supported only for compatibility, do not use this in new manuals.
   Prints
   .Dq is currently in beta test.
 .Ss \&Bx  .Ss \&Bx
   Format the
   .Bx
   version provided as an argument, or a default value if no
   argument is provided.
   .Pp
   Examples:
   .Dl \&.Bx 4.3 Tahoe
   .Dl \&.Bx 4.4
   .Dl \&.Bx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
 .Ss \&Cd  .Ss \&Cd
   Kernel configuration declaration.
   This denotes strings accepted by
   .Xr config 8 .
   It is most often used in section 4 manual pages.
   .Pp
   Examples:
   .Dl \&.Cd device le0 at scode?
   .Pp
   .Em Remarks :
   this macro is commonly abused by using quoted literals to retain
   whitespace and align consecutive
   .Sx \&Cd
   declarations.
   This practise is discouraged.
 .Ss \&Cm  .Ss \&Cm
   Command modifiers.
   Typically used for fixed strings passed as arguments, unless
   .Sx \&Fl
   is more appropriate.
   Also useful when specifying configuration options or keys.
   .Pp
   Examples:
   .Dl ".Nm mt Fl f Ar device Cm rewind"
   .Dl ".Nm ps Fl o Cm pid , Ns Cm command"
   .Dl ".Nm dd Cm if= Ns Ar file1 Cm of= Ns Ar file2"
   .Dl ".Cm IdentityFile Pa ~/.ssh/id_rsa"
   .Dl ".Cm LogLevel Dv DEBUG"
 .Ss \&D1  .Ss \&D1
   One-line indented display.
   This is formatted by the default rules and is useful for simple indented
   statements.
   It is followed by a newline.
   .Pp
   Examples:
   .Dl \&.D1 \&Fl abcdefgh
   .Pp
   See also
   .Sx \&Bd
   and
   .Sx \&Dl .
 .Ss \&Db  .Ss \&Db
   This macro is obsolete.
   No replacement is needed.
   It is ignored by
   .Xr mandoc 1
   and groff including its arguments.
   It was formerly used to toggle a debugging mode.
 .Ss \&Dc  .Ss \&Dc
   Close a
   .Sx \&Do
   block.
   Does not have any tail arguments.
 .Ss \&Dd  .Ss \&Dd
   Document date for display in the page footer.
   This is the mandatory first macro of any
   .Nm
   manual.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Dd Ar month day , year
   .Pp
   The
   .Ar month
   is the full English month name, the
   .Ar day
   is an optionally zero-padded numeral, and the
   .Ar year
   is the full four-digit year.
   .Pp
   Other arguments are not portable; the
   .Xr mandoc 1
   utility handles them as follows:
   .Bl -dash -offset 3n -compact
   .It
   To have the date automatically filled in by the
   .Ox
   version of
   .Xr cvs 1 ,
   the special string
   .Dq $\&Mdocdate$
   can be given as an argument.
   .It
   The traditional, purely numeric
   .Xr man 7
   format
   .Ar year Ns \(en Ns Ar month Ns \(en Ns Ar day
   is accepted, too.
   .It
   If a date string cannot be parsed, it is used verbatim.
   .It
   If no date string is given, the current date is used.
   .El
   .Pp
   Examples:
   .Dl \&.Dd $\&Mdocdate$
   .Dl \&.Dd $\&Mdocdate: July 21 2007$
   .Dl \&.Dd July 21, 2007
   .Pp
   See also
   .Sx \&Dt
   and
   .Sx \&Os .
 .Ss \&Dl  .Ss \&Dl
   One-line indented display.
   This is formatted as literal text and is useful for commands and
   invocations.
   It is followed by a newline.
   .Pp
   Examples:
   .Dl \&.Dl % mandoc mdoc.7 \e(ba less
   .Pp
   See also
   .Sx \&Ql ,
   .Sx \&Bd
   .Fl literal ,
   and
   .Sx \&D1 .
 .Ss \&Do  .Ss \&Do
   Begin a block enclosed by double quotes.
   Does not have any head arguments.
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Do
   April is the cruellest month
   \&.Dc
   \e(em T.S. Eliot
   .Ed
   .Pp
   See also
   .Sx \&Dq .
 .Ss \&Dq  .Ss \&Dq
   Encloses its arguments in
   .Dq typographic
   double-quotes.
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Dq April is the cruellest month
   \e(em T.S. Eliot
   .Ed
   .Pp
   See also
   .Sx \&Qq ,
   .Sx \&Sq ,
   and
   .Sx \&Do .
 .Ss \&Dt  .Ss \&Dt
   Document title for display in the page header.
   This is the mandatory second macro of any
   .Nm
   file.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Dt
   .Ar TITLE
   .Ar section
   .Op Ar arch
   .Ed
   .Pp
   Its arguments are as follows:
   .Bl -tag -width section -offset 2n
   .It Ar TITLE
   The document's title (name), defaulting to
   .Dq UNTITLED
   if unspecified.
   To achieve a uniform appearance of page header lines,
   it should by convention be all caps.
   .It Ar section
   The manual section.
   This may be one of
   .Cm 1
   .Pq General Commands ,
   .Cm 2
   .Pq System Calls ,
   .Cm 3
   .Pq Library Functions ,
   .Cm 3p
   .Pq Perl Library ,
   .Cm 4
   .Pq Device Drivers ,
   .Cm 5
   .Pq File Formats ,
   .Cm 6
   .Pq Games ,
   .Cm 7
   .Pq Miscellaneous Information ,
   .Cm 8
   .Pq System Manager's Manual ,
   or
   .Cm 9
   .Pq Kernel Developer's Manual .
   It should correspond to the manual's filename suffix and defaults to
   the empty string if unspecified.
   .It Ar arch
   This specifies the machine architecture a manual page applies to,
   where relevant, for example
   .Cm alpha ,
   .Cm amd64 ,
   .Cm i386 ,
   or
   .Cm sparc64 .
   The list of valid architectures varies by operating system.
   .El
   .Pp
   Examples:
   .Dl \&.Dt FOO 1
   .Dl \&.Dt FOO 9 i386
   .Pp
   See also
   .Sx \&Dd
   and
   .Sx \&Os .
 .Ss \&Dv  .Ss \&Dv
   Defined variables such as preprocessor constants, constant symbols,
   enumeration values, and so on.
   .Pp
   Examples:
   .Dl \&.Dv NULL
   .Dl \&.Dv BUFSIZ
   .Dl \&.Dv STDOUT_FILENO
   .Pp
   See also
   .Sx \&Er
   and
   .Sx \&Ev
   for special-purpose constants,
   .Sx \&Va
   for variable symbols, and
   .Sx \&Fd
   for listing preprocessor variable definitions in the
   .Em SYNOPSIS .
 .Ss \&Dx  .Ss \&Dx
   Format the
   .Dx
   version provided as an argument, or a default
   value if no argument is provided.
   .Pp
   Examples:
   .Dl \&.Dx 2.4.1
   .Dl \&.Dx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
 .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
   Request an italic font.
   If the output device does not provide that, underline.
   .Pp
   This is most often used for stress emphasis (not to be confused with
   importance, see
   .Sx \&Sy ) .
   In the rare cases where none of the semantic markup macros fit,
   it can also be used for technical terms and placeholders, except
   that for syntax elements,
   .Sx \&Sy
   and
   .Sx \&Ar
   are preferred, respectively.
   .Pp
   Examples:
   .Bd -literal -compact -offset indent
   Selected lines are those
   \&.Em not
   matching any of the specified patterns.
   Some of the functions use a
   \&.Em hold space
   to save the pattern space for subsequent retrieval.
   .Ed
   .Pp
   See also
   .Sx \&Bf ,
   .Sx \&Li ,
   .Sx \&No ,
   and
   .Sx \&Sy .
 .Ss \&En  .Ss \&En
   This macro is obsolete.
   Use
   .Sx \&Eo
   or any of the other enclosure macros.
   .Pp
   It encloses its argument in the delimiters specified by the last
   .Sx \&Es
   macro.
 .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 for definitions of the
   .Va errno
   libc global variable.
   This is most often used in section 2 and 3 manual pages.
   .Pp
   Examples:
   .Dl \&.Er EPERM
   .Dl \&.Er ENOENT
   .Pp
   See also
   .Sx \&Dv
   for general constants.
 .Ss \&Es  .Ss \&Es
   This macro is obsolete.
   Use
   .Sx \&Eo
   or any of the other enclosure macros.
   .Pp
   It takes two arguments, defining the delimiters to be used by subsequent
   .Sx \&En
   macros.
 .Ss \&Ev  .Ss \&Ev
   Environmental variables such as those specified in
   .Xr environ 7 .
   .Pp
   Examples:
   .Dl \&.Ev DISPLAY
   .Dl \&.Ev PATH
   .Pp
   See also
   .Sx \&Dv
   for general constants.
 .Ss \&Ex  .Ss \&Ex
   Insert a standard sentence regarding command exit values of 0 on success
   and >0 on failure.
   This is most often used in section 1, 6, and 8 manual pages.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Ex Fl std Op Ar utility ...
   .Pp
   If
   .Ar utility
   is not specified, the document's name set by
   .Sx \&Nm
   is used.
   Multiple
   .Ar utility
   arguments are treated as separate utilities.
   .Pp
   See also
   .Sx \&Rv .
 .Ss \&Fa  .Ss \&Fa
   Function argument or parameter.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Fa
   .Qo
   .Op Ar argtype
   .Op Ar argname
   .Qc Ar \&...
   .Ed
   .Pp
   Each argument may be a name and a type (recommended for the
   .Em SYNOPSIS
   section), a name alone (for function invocations),
   or a type alone (for function prototypes).
   If both a type and a name are given or if the type consists of multiple
   words, all words belonging to the same function argument have to be
   given in a single argument to the
   .Sx \&Fa
   macro.
   .Pp
   This macro is also used to specify the field name of a structure.
   .Pp
   Most often, the
   .Sx \&Fa
   macro is used in the
   .Em SYNOPSIS
   within
   .Sx \&Fo
   blocks when documenting multi-line function prototypes.
   If invoked with multiple arguments, the arguments are separated by a
   comma.
   Furthermore, if the following macro is another
   .Sx \&Fa ,
   the last argument will also have a trailing comma.
   .Pp
   Examples:
   .Dl \&.Fa \(dqconst char *p\(dq
   .Dl \&.Fa \(dqint a\(dq \(dqint b\(dq \(dqint c\(dq
   .Dl \&.Fa \(dqchar *\(dq size_t
   .Pp
   See also
   .Sx \&Fo .
 .Ss \&Fc  .Ss \&Fc
   End a function context started by
   .Sx \&Fo .
 .Ss \&Fd  .Ss \&Fd
   Preprocessor directive, in particular for listing it in the
   .Em SYNOPSIS .
   Historically, it was also used to document include files.
   The latter usage has been deprecated in favour of
   .Sx \&In .
   .Pp
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Fd
   .Li # Ns Ar directive
   .Op Ar argument ...
   .Ed
   .Pp
   Examples:
   .Dl \&.Fd #define sa_handler __sigaction_u.__sa_handler
   .Dl \&.Fd #define SIO_MAXNFDS
   .Dl \&.Fd #ifdef FS_DEBUG
   .Dl \&.Ft void
   .Dl \&.Fn dbg_open \(dqconst char *\(dq
   .Dl \&.Fd #endif
   .Pp
   See also
   .Sx MANUAL STRUCTURE ,
   .Sx \&In ,
   and
   .Sx \&Dv .
 .Ss \&Fl  .Ss \&Fl
   Command-line flag or option.
   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:
   .Dl ".Fl R Op Fl H | L | P"
   .Dl ".Op Fl 1AaCcdFfgHhikLlmnopqRrSsTtux"
   .Dl ".Fl type Cm d Fl name Pa CVS"
   .Dl ".Fl Ar signal_number"
   .Dl ".Fl o Fl"
   .Pp
   See also
   .Sx \&Cm .
 .Ss \&Fn  .Ss \&Fn
   A function name.
   Its syntax is as follows:
   .Bd -ragged -offset indent
   .Pf . Sx \&Fn
   .Op Ar functype
   .Ar funcname
   .Op Oo Ar argtype Oc Ar argname
   .Ed
   .Pp
   Function arguments are surrounded in parenthesis and
   are delimited by commas.
   If no arguments are specified, blank parenthesis are output.
   In the
   .Em SYNOPSIS
   section, this macro starts a new output line,
   and a blank line is automatically inserted between function definitions.
   .Pp
   Examples:
   .Dl \&.Fn \(dqint funcname\(dq \(dqint arg0\(dq \(dqint arg1\(dq
   .Dl \&.Fn funcname \(dqint arg0\(dq
   .Dl \&.Fn funcname arg0
   .Pp
   .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 ,
   .Sx \&Fo ,
   and
   .Sx \&Ft .
 .Ss \&Fo  .Ss \&Fo
   Begin a function block.
   This is a multi-line version of
   .Sx \&Fn .
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Fo Ar funcname
   .Pp
   Invocations usually occur in the following context:
   .Bd -ragged -offset indent
   .Pf \. Sx \&Ft Ar functype
   .br
   .Pf \. Sx \&Fo Ar funcname
   .br
   .Pf \. Sx \&Fa Qq Ar argtype Ar argname
   .br
   \&.\.\.
   .br
   .Pf \. Sx \&Fc
   .Ed
   .Pp
   A
   .Sx \&Fo
   scope is closed by
   .Sx \&Fc .
   .Pp
   See also
   .Sx MANUAL STRUCTURE ,
   .Sx \&Fa ,
   .Sx \&Fc ,
   and
   .Sx \&Ft .
 .Ss \&Fr  .Ss \&Fr
   This macro is obsolete.
   No replacement markup is needed.
   .Pp
   It was used to show numerical function return values in an italic font.
 .Ss \&Ft  .Ss \&Ft
   A function type.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Ft Ar functype
   .Pp
   In the
   .Em SYNOPSIS
   section, a new output line is started after this macro.
   .Pp
   Examples:
   .Dl \&.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
   .Fx
   version provided as an argument, or a default value
   if no argument is provided.
   .Pp
   Examples:
   .Dl \&.Fx 7.1
   .Dl \&.Fx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
 .Ss \&Hf  .Ss \&Hf
   This macro is not implemented in
   .Xr mandoc 1 .
   .Pp
   It was used to include the contents of a (header) file literally.
   The syntax was:
   .Pp
   .Dl Pf . Sx \&Hf Ar filename
 .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:
   .Dl \&.Ic :wq
   .Dl \&.Ic hash
   .Dl \&.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
   The name of an include file.
   This macro is most often used in section 2, 3, and 9 manual pages.
   .Pp
   When invoked as the first macro on an input line in the
   .Em SYNOPSIS
   section, the argument is displayed in angle brackets
   and preceded by
   .Qq #include ,
   and a blank line is inserted in front if there is a preceding
   function declaration.
   In other sections, it only encloses its argument in angle brackets
   and causes no line break.
   .Pp
   Examples:
   .Dl \&.In sys/types.h
   .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 Ar 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 Ar cell Op Sx \&Ta Ar cell ...
   .D1 Pf \. Sx \&It Ar cell Op <TAB> Ar cell ...
   .Pp
   The arguments consist of one or more lines of text and macros
   representing a complete table line.
   Cells within the line are delimited by the special
   .Sx \&Ta
   block macro or by literal tab characters.
   .Pp
   Using literal tabs is strongly discouraged because they are very
   hard to use correctly and
   .Nm
   code using them is very hard to read.
   In particular, a blank character is syntactically significant
   before and after the literal tab character.
   If a word precedes or follows the tab without an intervening blank,
   that word is never interpreted as a macro call, but always output
   literally.
   .Pp
   The tab cell delimiter may only be used within the
   .Sx \&It
   line itself; on following lines, only the
   .Sx \&Ta
   macro can be used to delimit cells, and portability requires that
   .Sx \&Ta
   is called by other macros: some parsers do not recognize it when
   it appears as the first macro on a line.
   .Pp
   Note that quoted strings may span tab-delimited cells on an
   .Sx \&It
   line.
   For example,
   .Pp
   .Dl .It \(dqcol1 ,\& <TAB> col2 ,\(dq \&;
   .Pp
   will preserve the whitespace before both commas,
   but not the whitespace before the semicolon.
   .Pp
   See also
   .Sx \&Bl .
 .Ss \&Lb  .Ss \&Lb
   Specify a library.
   The syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Lb Ar library
   .Pp
   The
   .Ar 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:
   .Dl \&.Lb libz
   .Dl \&.Lb libmandoc
 .Ss \&Li  .Ss \&Li
   Denotes text that should be in a
   .Li literal
   font mode.
   Note that this is a presentation term and should not be used for
   stylistically decorating technical terms.
   .Pp
   On terminal output devices, this is often indistinguishable from
   normal text.
   .Pp
   See also
   .Sx \&Bf ,
   .Sx \&Em ,
   .Sx \&No ,
   and
   .Sx \&Sy .
 .Ss \&Lk  .Ss \&Lk
   Format a hyperlink.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Lk Ar uri Op Ar name
   .Pp
   Examples:
   .Dl \&.Lk http://bsd.lv \(dqThe BSD.lv Project\(dq
   .Dl \&.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 Ar symbol
   .Pp
   Examples:
   .Dl \&.Ms sigma
   .Dl \&.Ms aleph
 .Ss \&Mt  .Ss \&Mt
   Format a
   .Dq mailto:
   hyperlink.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Mt Ar address
   .Pp
   Examples:
   .Dl \&.Mt discuss@manpages.bsd.lv
   .Dl \&.An Kristaps Dzonsons \&Aq \&Mt kristaps@bsd.lv
 .Ss \&Nd  .Ss \&Nd
   A one line description of the manual's content.
   This is the mandatory last macro of the
   .Em NAME
   section and not appropriate for other sections.
   .Pp
   Examples:
   .Dl Pf . Sx \&Nd mdoc language reference
   .Dl Pf . 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
   Normal text.
   Closes the scope of any preceding in-line macro.
   When used after physical formatting macros like
   .Sx \&Em
   or
   .Sx \&Sy ,
   switches back to the standard font face and weight.
   Can also be used to embed plain text strings in macro lines
   using semantic annotation macros.
   .Pp
   Examples:
   .Dl ".Em italic , Sy bold , No and roman"
   .Pp
   .Bd -literal -offset indent -compact
   \&.Sm off
   \&.Cm :C No / Ar pattern No / Ar replacement No /
   \&.Sm on
   .Ed
   .Pp
   See also
   .Sx \&Em ,
   .Sx \&Li ,
   and
   .Sx \&Sy .
 .Ss \&Ns  .Ss \&Ns
   Suppress a space between the output of the preceding macro
   and the following text or macro.
   Following invocation, input is interpreted as normal text
   just like after an
   .Sx \&No
   macro.
   .Pp
   This has no effect when invoked at the start of a macro line.
   .Pp
   Examples:
   .Dl ".Ar name Ns = Ns Ar value"
   .Dl ".Cm :M Ns Ar pattern"
   .Dl ".Fl o Ns Ar output"
   .Pp
   See also
   .Sx \&No
   and
   .Sx \&Sm .
 .Ss \&Nx  .Ss \&Nx
   Format the
   .Nx
   version provided as an argument, or a default value if
   no argument is provided.
   .Pp
   Examples:
   .Dl \&.Nx 5.01
   .Dl \&.Nx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   and
   .Sx \&Ox .
 .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
   Optional part of a command line.
   Prints the argument(s) in brackets.
   This is most often used in the
   .Em SYNOPSIS
   section of section 1 and 8 manual pages.
   .Pp
   Examples:
   .Dl \&.Op \&Fl a \&Ar b
   .Dl \&.Op \&Ar a | b
   .Pp
   See also
   .Sx \&Oo .
 .Ss \&Os  .Ss \&Os
   Operating system version for display in the page footer.
   This is the mandatory third macro of
   any
   .Nm
   file.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Os Op Ar system Op Ar version
   .Pp
   The optional
   .Ar system
   parameter specifies the relevant operating system or environment.
   It is suggested to leave it unspecified, in which case
   .Xr mandoc 1
   uses its
   .Fl Ios
   argument or, if that isn't specified either,
   .Fa sysname
   and
   .Fa release
   as returned by
   .Xr uname 3 .
   .Pp
   Examples:
   .Dl \&.Os
   .Dl \&.Os KTH/CSC/TCS
   .Dl \&.Os BSD 4.3
   .Pp
   See also
   .Sx \&Dd
   and
   .Sx \&Dt .
 .Ss \&Ot  .Ss \&Ot
   This macro is obsolete.
   Use
   .Sx \&Ft
   instead; with
   .Xr mandoc 1 ,
   both have the same effect.
   .Pp
   Historical
   .Nm
   packages described it as
   .Dq "old function type (FORTRAN)" .
 .Ss \&Ox  .Ss \&Ox
   Format the
   .Ox
   version provided as an argument, or a default value
   if no argument is provided.
   .Pp
   Examples:
   .Dl \&.Ox 4.5
   .Dl \&.Ox
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   and
   .Sx \&Nx .
 .Ss \&Pa  .Ss \&Pa
   An absolute or relative file system path, or a file or directory name.
   If an argument is not provided, the character
   .Sq \(ti
   is used as a default.
   .Pp
   Examples:
   .Dl \&.Pa /usr/bin/mandoc
   .Dl \&.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 between its argument and the following macro.
   Its syntax is as follows:
   .Pp
   .D1 .Pf Ar prefix macro arguments ...
   .Pp
   This is equivalent to:
   .Pp
   .D1 .No \e& Ns Ar prefix No \&Ns Ar macro arguments ...
   .Pp
   The
   .Ar prefix
   argument is not parsed for macro names or delimiters,
   but used verbatim as if it were escaped.
   .Pp
   Examples:
   .Dl ".Pf $ Ar variable_name"
   .Dl ".Pf . Ar macro_name"
   .Dl ".Pf 0x Ar hex_digits"
   .Pp
   See also
   .Sx \&Ns
   and
   .Sx \&Sm .
 .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.
   .Pp
   Paragraph breaks are not needed before or after
   .Sx \&Sh
   or
   .Sx \&Ss
   macros or before displays
   .Pq Sx \&Bd
   or lists
   .Pq Sx \&Bl
   unless the
   .Fl compact
   flag is given.
 .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
   In-line literal display.
   This can for example be used for complete command invocations and
   for multi-word code fragments when more specific markup is not
   appropriate and an indented display is not desired.
   While
   .Xr mandoc 1
   always encloses the arguments in single quotes, other formatters
   usually omit the quotes on non-terminal output devices when the
   arguments have three or more characters.
   .Pp
   See also
   .Sx \&Dl
   and
   .Sx \&Bd
   .Fl literal .
 .Ss \&Qo  .Ss \&Qo
   Multi-line version of
   .Sx \&Qq .
 .Ss \&Qq  .Ss \&Qq
 .  Encloses its arguments in
   .Qq 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 and 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 986  contain
Line 2272  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
 \&.%B Introduction to Automata Theory, Languages, and Computation  \&.%B Introduction to Automata Theory, Languages, and Computation
 \&.%I Addison-Wesley  \&.%I Addison-Wesley
 \&.%C Reading, Massachusettes  \&.%C Reading, Massachusetts
 \&.%D 1979  \&.%D 1979
 \&.Re  \&.Re
 .Ed  .Ed
Line 1007  If an
Line 2294  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
   Insert a standard sentence regarding a function call's return value of 0
   on success and \-1 on error, with the
   .Va errno
   libc global variable set on error.
   Its syntax is as follows:
   .Pp
   .D1 Pf \. Sx \&Rv Fl std Op Ar function ...
   .Pp
   If
   .Ar function
   is not specified, the document's name set by
   .Sx \&Nm
   is used.
   Multiple
   .Ar function
   arguments are treated as separate functions.
   .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 .
   Although this macro is parsed, it should not consist of child node or it
   may not be linked with
   .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 Op 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 text lines
   still get normal spacing between words and sentences.
   .Pp
   When called without an argument, the
   .Sx \&Sm
   macro toggles the spacing mode.
   Using this is not recommended because it makes the code harder to read.
 .Ss \&So  .Ss \&So
   Multi-line version of
   .Sx \&Sq .
 .Ss \&Sq  .Ss \&Sq
   Encloses its arguments in
   .Sq typewriter
   single-quotes.
   .Pp
   See also
   .Sx \&Dq ,
   .Sx \&Qq ,
   and
   .Sx \&So .
 .Ss \&Ss  .Ss \&Ss
   Begin a new subsection.
   Unlike with
   .Sx \&Sh ,
   there is no convention for the naming of subsections.
   Except
   .Em DESCRIPTION ,
   the conventional sections described in
   .Sx MANUAL STRUCTURE
   rarely have subsections.
   .Pp
   Sub-section names should be unique so that they may be keyed by
   .Sx \&Sx .
   Although this macro is parsed, it should not consist of child node or it
   may not be linked with
   .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.
   Where multiple lines are given without a blank line in between,
   they all refer to the same standard, and using the first form
   is recommended.
   .Bl -tag -width 1n
   .It C language standards
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-ansiC
   .St -ansiC
   .It \-ansiC-89
   .St -ansiC-89
   .It \-isoC
   .St -isoC
   .It \-isoC-90
   .St -isoC-90
   .br
   The original C standard.
   .Pp
   .It \-isoC-amd1
   .St -isoC-amd1
   .Pp
   .It \-isoC-tcor1
   .St -isoC-tcor1
   .Pp
   .It \-isoC-tcor2
   .St -isoC-tcor2
   .Pp
   .It \-isoC-99
   .St -isoC-99
   .br
   The second major version of the C language standard.
   .Pp
   .It \-isoC-2011
   .St -isoC-2011
   .br
   The third major version of the C language standard.
   .El
   .It POSIX.1 before the Single UNIX Specification
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-p1003.1-88
   .St -p1003.1-88
   .It \-p1003.1
   .St -p1003.1
   .br
   The original POSIX standard, based on ANSI C.
   .Pp
   .It \-p1003.1-90
   .St -p1003.1-90
   .It \-iso9945-1-90
   .St -iso9945-1-90
   .br
   The first update of POSIX.1.
   .Pp
   .It \-p1003.1b-93
   .St -p1003.1b-93
   .It \-p1003.1b
   .St -p1003.1b
   .br
   Real-time extensions.
   .Pp
   .It \-p1003.1c-95
   .St -p1003.1c-95
   .br
   POSIX thread interfaces.
   .Pp
   .It \-p1003.1i-95
   .St -p1003.1i-95
   .br
   Technical Corrigendum.
   .Pp
   .It \-p1003.1-96
   .St -p1003.1-96
   .It \-iso9945-1-96
   .St -iso9945-1-96
   .br
   Includes POSIX.1-1990, 1b, 1c, and 1i.
   .El
   .It X/Open Portability Guide version 4 and related standards
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-xpg3
   .St -xpg3
   .br
   An XPG4 precursor, published in 1989.
   .Pp
   .It \-p1003.2
   .St -p1003.2
   .It \-p1003.2-92
   .St -p1003.2-92
   .It \-iso9945-2-93
   .St -iso9945-2-93
   .br
   An XCU4 precursor.
   .Pp
   .It \-p1003.2a-92
   .St -p1003.2a-92
   .br
   Updates to POSIX.2.
   .Pp
   .It \-xpg4
   .St -xpg4
   .br
   Based on POSIX.1 and POSIX.2, published in 1992.
   .El
   .It Single UNIX Specification version 1 and related standards
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-susv1
   .St -susv1
   .It \-xpg4.2
   .St -xpg4.2
   .br
   This standard was published in 1994.
   It was used as the basis for UNIX 95 certification.
   The following three refer to parts of it.
   .Pp
   .It \-xsh4.2
   .St -xsh4.2
   .Pp
   .It \-xcurses4.2
   .St -xcurses4.2
   .Pp
   .It \-p1003.1g-2000
   .St -p1003.1g-2000
   .br
   Networking APIs, including sockets.
   .Pp
   .It \-svid4
   .St -svid4 ,
   .br
   Published in 1995.
   .El
   .It Single UNIX Specification version 2 and related standards
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-susv2
   .St -susv2
   This Standard was published in 1997
   and is also called X/Open Portability Guide version 5.
   It was used as the basis for UNIX 98 certification.
   The following refer to parts of it.
   .Pp
   .It \-xbd5
   .St -xbd5
   .Pp
   .It \-xsh5
   .St -xsh5
   .Pp
   .It \-xcu5
   .St -xcu5
   .Pp
   .It \-xns5
   .St -xns5
   .It \-xns5.2
   .St -xns5.2
   .El
   .It Single UNIX Specification version 3
   .Pp
   .Bl -tag -width "-p1003.1-2001" -compact
   .It \-p1003.1-2001
   .St -p1003.1-2001
   .It \-susv3
   .St -susv3
   .br
   This standard is based on C99, SUSv2, POSIX.1-1996, 1d, and 1j.
   It is also called X/Open Portability Guide version 6.
   It is used as the basis for UNIX 03 certification.
   .Pp
   .It \-p1003.1-2004
   .St -p1003.1-2004
   .br
   The second and last Technical Corrigendum.
   .El
   .It Single UNIX Specification version 4
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-p1003.1-2008
   .St -p1003.1-2008
   .It \-susv4
   .St -susv4
   .br
   This standard is also called
   X/Open Portability Guide version 7.
   .El
   .It Other standards
   .Pp
   .Bl -tag -width "-p1003.1g-2000" -compact
   .It \-ieee754
   .St -ieee754
   .br
   Floating-point arithmetic.
   .Pp
   .It \-iso8601
   .St -iso8601
   .br
   Representation of dates and times, published in 1988.
   .Pp
   .It \-iso8802-3
   .St -iso8802-3
   .br
   Ethernet local area networks.
   .Pp
   .It \-ieee1275-94
   .St -ieee1275-94
   .El
   .El
 .Ss \&Sx  .Ss \&Sx
   Reference a section or subsection in the same manual page.
   The referenced section or subsection name must be identical to the
   enclosed argument, including whitespace.
   .Pp
   Examples:
   .Dl \&.Sx MANUAL STRUCTURE
   .Pp
   See also
   .Sx \&Sh
   and
   .Sx \&Ss .
 .Ss \&Sy  .Ss \&Sy
   Request a boldface font.
   .Pp
   This is most often used to indicate importance or seriousness (not to be
   confused with stress emphasis, see
   .Sx \&Em ) .
   When none of the semantic macros fit, it is also adequate for syntax
   elements that have to be given or that appear verbatim.
   .Pp
   Examples:
   .Bd -literal -compact -offset indent
   \&.Sy Warning :
   If
   \&.Sy s
   appears in the owner permissions, set-user-ID mode is set.
   This utility replaces the former
   \&.Sy dumpdir
   program.
   .Ed
   .Pp
   See also
   .Sx \&Bf ,
   .Sx \&Em ,
   .Sx \&Li ,
   and
   .Sx \&No .
   .Ss \&Ta
   Table cell separator in
   .Sx \&Bl Fl column
   lists; can only be used below
   .Sx \&It .
 .Ss \&Tn  .Ss \&Tn
   Supported only for compatibility, do not use this in new manuals.
   Even though the macro name
   .Pq Dq tradename
   suggests a semantic function, historic usage is inconsistent, mostly
   using it as a presentation-level macro to request a small caps font.
 .Ss \&Ud  .Ss \&Ud
   Supported only for compatibility, do not use this in new manuals.
   Prints out
   .Dq currently under development.
 .Ss \&Ux  .Ss \&Ux
   Supported only for compatibility, do not use this in new manuals.
   Prints out
   .Dq Ux .
 .Ss \&Va  .Ss \&Va
   A variable name.
   .Pp
   Examples:
   .Dl \&.Va foo
   .Dl \&.Va const char *bar ;
   .Pp
   For function arguments and parameters, use
   .Sx \&Fa
   instead.
   For declarations of global variables in the
   .Em SYNOPSIS
   section, use
   .Sx \&Vt .
 .Ss \&Vt  .Ss \&Vt
   A variable type.
   .Pp
   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 on an input line in the
   .Em SYNOPSIS
   section, else it accepts ordinary
   .Sx In-line
   syntax.
   In the former case, this macro starts a new output line,
   and a blank line is inserted in front if there is a preceding
   function definition or include directive.
   .Pp
   Examples:
   .Dl \&.Vt unsigned char
   .Dl \&.Vt extern const char * const sys_signame[] \&;
   .Pp
   For parameters in function prototypes, use
   .Sx \&Fa
   instead, for function return types
   .Sx \&Ft ,
   and for variable names outside the
   .Em SYNOPSIS
   section
   .Sx \&Va ,
   even when including a type with the name.
   See also
   .Sx MANUAL STRUCTURE .
 .Ss \&Xc  .Ss \&Xc
   Close a scope opened by
   .Sx \&Xo .
 .Ss \&Xo  .Ss \&Xo
   Extend the header of an
   .Sx \&It
   macro or the body of a partial-implicit block macro
   beyond the end of the input line.
   This macro originally existed to work around the 9-argument limit
   of historic
   .Xr roff 7 .
 .Ss \&Xr  .Ss \&Xr
 .Ss \&br  Link to another manual
 .Ss \&sp  .Pq Qq cross-reference .
 .  Its syntax is as follows:
 .  .Pp
   .D1 Pf \. Sx \&Xr Ar name section
   .Pp
   Cross reference the
   .Ar name
   and
   .Ar section
   number of another man page.
   .Pp
   Examples:
   .Dl \&.Xr mandoc 1
   .Dl \&.Xr mandoc 1 \&;
   .Dl \&.Xr mandoc 1 \&Ns s behaviour
   .Sh MACRO SYNTAX
   The syntax of a macro depends on its classification.
   In this section,
   .Sq \-arg
   refers to macro arguments, which may be followed by zero or more
   .Sq parm
   parameters;
   .Sq \&Yo
   opens the scope of a macro; and if specified,
   .Sq \&Yc
   closes it out.
   .Pp
   The
   .Em Callable
   column indicates that the macro may also be called by passing its name
   as an argument to another macro.
   For example,
   .Sq \&.Op \&Fl O \&Ar file
   produces
   .Sq Op Fl O Ar file .
   To prevent a macro call and render the macro name literally,
   escape it by prepending a zero-width space,
   .Sq \e& .
   For example,
   .Sq \&Op \e&Fl O
   produces
   .Sq Op \&Fl O .
   If a macro is not callable but its name appears as an argument
   to another macro, it is interpreted as opaque text.
   For example,
   .Sq \&.Fl \&Sh
   produces
   .Sq Fl \&Sh .
   .Pp
   The
   .Em Parsed
   column indicates whether the macro may call other macros by receiving
   their names as arguments.
   If a macro is not parsed but the name of another macro appears
   as an argument, it is interpreted as opaque text.
   .Pp
   The
   .Em Scope
   column, if applicable, describes closure rules.
   .Ss Block full-explicit
   Multi-line scope closed by an explicit closing macro.
   All macros contains bodies; only
   .Sx \&Bf
   and
   .Pq optionally
   .Sx \&Bl
   contain a head.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB
   \(lBbody...\(rB
   \&.Yc
   .Ed
   .Bl -column "MacroX" "CallableX" "ParsedX" "closed by XXX" -offset indent
   .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 \&Bf  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ef
   .It Sx \&Bk  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Ek
   .It Sx \&Bl  Ta    \&No     Ta    \&No     Ta    closed by Sx \&El
   .It Sx \&Ed  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bd
   .It Sx \&Ef  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bf
   .It Sx \&Ek  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bk
   .It Sx \&El  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Bl
   .El
   .Ss Block full-implicit
   Multi-line scope closed by end-of-file or implicitly by another macro.
   All macros have bodies; some
   .Po
   .Sx \&It Fl bullet ,
   .Fl hyphen ,
   .Fl dash ,
   .Fl enum ,
   .Fl item
   .Pc
   don't have heads; only one
   .Po
   .Sx \&It
   in
   .Sx \&Bl Fl column
   .Pc
   has multiple heads.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB
   \(lBbody...\(rB
   .Ed
   .Bl -column "MacroX" "CallableX" "ParsedX" "closed by XXXXXXXXXXX" -offset indent
   .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 \&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 Yes  Ta closed by Sx \&Sh
   .It Sx \&Ss Ta \&No Ta Yes  Ta closed by Sx \&Sh , Sx \&Ss
   .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
   Like block full-explicit, but also with single-line scope.
   Each has at least a body and, in limited circumstances, a head
   .Po
   .Sx \&Fo ,
   .Sx \&Eo
   .Pc
   and/or tail
   .Pq Sx \&Ec .
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB
   \(lBbody...\(rB
   \&.Yc \(lBtail...\(rB
   
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB \
   \(lBbody...\(rB \&Yc \(lBtail...\(rB
   .Ed
   .Bl -column "MacroX" "CallableX" "ParsedX" "closed by XXXX" -offset indent
   .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 \&Ao  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ac
   .It Sx \&Bc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Bo
   .It Sx \&Bo  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bc
   .It Sx \&Brc Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bro
   .It Sx \&Bro Ta    Yes      Ta    Yes      Ta    closed by Sx \&Brc
   .It Sx \&Dc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Do
   .It Sx \&Do  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Dc
   .It Sx \&Ec  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Eo
   .It Sx \&Eo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ec
   .It Sx \&Fc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Fo
   .It Sx \&Fo  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Fc
   .It Sx \&Oc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Oo
   .It Sx \&Oo  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Oc
   .It Sx \&Pc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Po
   .It Sx \&Po  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Pc
   .It Sx \&Qc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Oo
   .It Sx \&Qo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Oc
   .It Sx \&Re  Ta    \&No     Ta    \&No     Ta    opened by Sx \&Rs
   .It Sx \&Rs  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Re
   .It Sx \&Sc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&So
   .It Sx \&So  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Sc
   .It Sx \&Xc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Xo
   .It Sx \&Xo  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Xc
   .El
   .Ss Block partial-implicit
   Like block full-implicit, but with single-line scope closed by the
   end of the line.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB
   .Ed
   .Bl -column "MacroX" "CallableX" "ParsedX" -offset indent
   .It Em Macro Ta Em Callable Ta Em Parsed
   .It Sx \&Aq  Ta    Yes      Ta    Yes
   .It Sx \&Bq  Ta    Yes      Ta    Yes
   .It Sx \&Brq Ta    Yes      Ta    Yes
   .It Sx \&D1  Ta    \&No     Ta    \&Yes
   .It Sx \&Dl  Ta    \&No     Ta    Yes
   .It Sx \&Dq  Ta    Yes      Ta    Yes
   .It Sx \&En  Ta    Yes      Ta    Yes
   .It Sx \&Op  Ta    Yes      Ta    Yes
   .It Sx \&Pq  Ta    Yes      Ta    Yes
   .It Sx \&Ql  Ta    Yes      Ta    Yes
   .It Sx \&Qq  Ta    Yes      Ta    Yes
   .It Sx \&Sq  Ta    Yes      Ta    Yes
   .It Sx \&Vt  Ta    Yes      Ta    Yes
   .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 Special block macro
   The
   .Sx \&Ta
   macro can only be used below
   .Sx \&It
   in
   .Sx \&Bl Fl column
   lists.
   It delimits blocks representing table cells;
   these blocks have bodies, but no heads.
   .Bl -column "MacroX" "CallableX" "ParsedX" "closed by XXXX" -offset indent
   .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Scope
   .It Sx \&Ta  Ta    Yes      Ta    Yes    Ta closed by Sx \&Ta , Sx \&It
   .El
   .Ss In-line
   Closed by the end of the line, fixed argument lengths,
   and/or subsequent macros.
   In-line macros have only text children.
   If a number (or inequality) of arguments is
   .Pq n ,
   then the macro accepts an arbitrary number of arguments.
   .Bd -literal -offset indent
   \&.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 arg0 arg1 argN
   .Ed
   .Bl -column "MacroX" "CallableX" "ParsedX" "Arguments" -offset indent
   .It Em Macro Ta Em Callable Ta Em Parsed Ta Em Arguments
   .It Sx \&%A  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 \&%D  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%I  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%J  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%N  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%O  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%P  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%Q  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%R  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%T  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%U  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&%V  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&Ad  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&An  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Ap  Ta    Yes      Ta    Yes      Ta    0
   .It Sx \&Ar  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&At  Ta    Yes      Ta    Yes      Ta    1
   .It Sx \&Bsx Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Bt  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Bx  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Cd  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Cm  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Db  Ta    \&No     Ta    \&No     Ta    1
   .It Sx \&Dd  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Dt  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Dv  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Dx  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Em  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Er  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Es  Ta    Yes      Ta    Yes      Ta    2
   .It Sx \&Ev  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Ex  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Fa  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Fd  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&Fl  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Fn  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Fr  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Ft  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Fx  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Hf  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Ic  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&In  Ta    \&No     Ta    \&No     Ta    1
   .It Sx \&Lb  Ta    \&No     Ta    \&No     Ta    1
   .It Sx \&Li  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Lk  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Lp  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Ms  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Mt  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Nm  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&No  Ta    Yes      Ta    Yes      Ta    0
   .It Sx \&Ns  Ta    Yes      Ta    Yes      Ta    0
   .It Sx \&Nx  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Os  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Ot  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Ox  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Pa  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Pf  Ta    Yes      Ta    Yes      Ta    1
   .It Sx \&Pp  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Rv  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Sm  Ta    \&No     Ta    \&No     Ta    <2
   .It Sx \&St  Ta    \&No     Ta    Yes      Ta    1
   .It Sx \&Sx  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Sy  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Tn  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Ud  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Ux  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 \&Xr  Ta    Yes      Ta    Yes      Ta    2
   .El
   .Ss Delimiters
   When a macro argument consists of one single input character
   considered as a delimiter, the argument gets special handling.
   This does not apply when delimiters appear in arguments containing
   more than one character.
   Consequently, to prevent special handling and just handle it
   like any other argument, a delimiter can be escaped by prepending
   a zero-width space
   .Pq Sq \e& .
   In text lines, delimiters never need escaping, but may be used
   as normal punctuation.
   .Pp
   For many macros, when the leading arguments are opening delimiters,
   these delimiters are put before the macro scope,
   and when the trailing arguments are closing delimiters,
   these delimiters are put after the macro scope.
   Spacing is suppressed after opening delimiters
   and before closing delimiters.
   For example,
   .Pp
   .D1 Pf \. \&Aq "( [ word ] ) ."
   .Pp
   renders as:
   .Pp
   .D1 Aq ( [ word ] ) .
   .Pp
   Opening delimiters are:
   .Pp
   .Bl -tag -width Ds -offset indent -compact
   .It \&(
   left parenthesis
   .It \&[
   left bracket
   .El
   .Pp
   Closing delimiters are:
   .Pp
   .Bl -tag -width Ds -offset indent -compact
   .It \&.
   period
   .It \&,
   comma
   .It \&:
   colon
   .It \&;
   semicolon
   .It \&)
   right parenthesis
   .It \&]
   right bracket
   .It \&?
   question mark
   .It \&!
   exclamation mark
   .El
   .Pp
   Note that even a period preceded by a backslash
   .Pq Sq \e.\&
   gets this special handling; use
   .Sq \e&.
   to prevent that.
   .Pp
   Many in-line macros interrupt their scope when they encounter
   delimiters, and resume their scope when more arguments follow that
   are not delimiters.
   For example,
   .Pp
   .D1 Pf \. \&Fl "a ( b | c \e*(Ba d ) e"
   .Pp
   renders as:
   .Pp
   .D1 Fl a ( b | c \*(Ba d ) e
   .Pp
   This applies to both opening and closing delimiters,
   and also to the middle delimiter, which does not suppress spacing:
   .Pp
   .Bl -tag -width Ds -offset indent -compact
   .It \&|
   vertical bar
   .El
   .Pp
   As a special case, the predefined string \e*(Ba is handled and rendered
   in the same way as a plain
   .Sq \&|
   character.
   Using this predefined string is not recommended in new manuals.
   .Ss Font handling
   In
   .Nm
   documents, usage of semantic markup is recommended in order to have
   proper fonts automatically selected; only when no fitting semantic markup
   is available, consider falling back to
   .Sx Physical markup
   macros.
   Whenever any
   .Nm
   macro switches the
   .Xr roff 7
   font mode, it will automatically restore the previous font when exiting
   its scope.
   Manually switching the font using the
   .Xr roff 7
   .Ql \ef
   font escape sequences is never required.
 .Sh COMPATIBILITY  .Sh COMPATIBILITY
 This section documents compatibility with other roff implementations, at  This section provides an incomplete list of compatibility issues
 this time limited to  between mandoc and GNU troff
 .Xr groff 1 .  .Pq Qq groff .
 The term  
 .Qq historic groff  
 refers to those versions before the  
 .Pa doc.tmac  
 file re-write  
 .Pq somewhere between 1.15 and 1.19 .  
 .  
 .Pp  .Pp
   The following problematic behaviour is found in groff:
   .Pp
 .Bl -dash -compact  .Bl -dash -compact
 .It  .It
 Negative scaling units are now truncated to zero instead of creating  .Sx \&Dd
 interesting conditions, such as with  with non-standard arguments behaves very strangely.
 .Sq \&sp -1i .  When there are three arguments, they are printed verbatim.
 Furthermore, the  Any other number of arguments is replaced by the current date,
 .Sq f  but without any arguments the string
 scaling unit, while accepted, is rendered as the default unit.  .Dq Epoch
   is printed.
 .It  .It
 In quoted literals, groff allowed pair-wise double-quotes to produce a  .Sx \&Lk
 standalone double-quote in formatted output.  This idiosyncratic  only accepts a single link-name argument; the remainder is misformatted.
 behaviour is no longer applicable.  
 .It  .It
 Display types  .Sx \&Pa
 .Sx \&Bd Fl center  does not format its arguments when used in the FILES section under
 and  certain list types.
 .Fl right  
 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 \&Ta
 lines (except when in literal mode), while groff would retain whitespace  can only be called by other macros, but not at the beginning of a line.
 in free-form text lines.  
 .It  .It
 Historic groff has many un-callable macros.  Most of these (excluding  .Sx \&%C
 some block-level macros) are now callable, conforming to the  is not implemented (up to and including groff-1.22.2).
 non-historic groff version.  
 .It  .It
 The vertical bar  .Sq \ef
 .Sq \(ba  .Pq font face
 made historic groff  and
 .Qq go orbital  .Sq \eF
 but is a proper delimiter in this implementation.  .Pq font family face
   .Sx Text Decoration
   escapes behave irregularly when specified within line-macro scopes.
 .It  .It
 .Sx \&It Fl nested  Negative scaling units return to prior lines.
 is assumed for all lists (it wasn't in historic groff): any list may be  Instead, mandoc truncates them to zero.
 nested and  .El
 .Fl enum  .Pp
 lists will restart the sequence only for the sub-list.  The following features are unimplemented in mandoc:
   .Pp
   .Bl -dash -compact
 .It  .It
 Some manuals use  .Sx \&Bd
 .Sx \&Li  .Fl file Ar file
 incorrectly by following it with a reserved character and expecting the  is unsupported for security reasons.
 delimiter to render.  This is not supported.  
 .It  .It
 In groff, the  .Sx \&Bd
 .Sx \&Fo  .Fl filled
 macro only produces the first parameter.  This is no longer the case.  does not adjust the right margin, but is an alias for
   .Sx \&Bd
   .Fl ragged .
   .It
   .Sx \&Bd
   .Fl literal
   does not use a literal font, but is an alias for
   .Sx \&Bd
   .Fl unfilled .
   .It
   .Sx \&Bd
   .Fl offset Cm center
   and
   .Fl offset Cm right
   don't work.
   Groff does not implement centered and flush-right rendering either,
   but produces large indentations.
 .El  .El
 .  
 .  
 .Sh SEE ALSO  .Sh SEE ALSO
   .Xr man 1 ,
 .Xr mandoc 1 ,  .Xr mandoc 1 ,
 .Xr mandoc_char 7  .Xr eqn 7 ,
 .  .Xr man 7 ,
 .  .Xr mandoc_char 7 ,
   .Xr roff 7 ,
   .Xr tbl 7
   .Pp
   The web page
   .Lk http://mdocml.bsd.lv/mdoc/ "extended documentation for the mdoc language"
   provides a few tutorial-style pages for beginners, an extensive style
   guide for advanced authors, and an alphabetic index helping to choose
   the best macros for various kinds of content.
   .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 Mt 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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changed lines
  Added in v.1.268
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