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Diff for /mandoc/mdoc.7 between version 1.20 and 1.112

version 1.20, 2009/04/12 19:19:57 version 1.112, 2010/05/31 10:19:31
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 .\" $Id$  .\"     $Id$
 .\"  .\"
 .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@openbsd.org>  .\" Copyright (c) 2009 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"  .\"
 .\" 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  .\" purpose with or without fee is hereby granted, provided that the above
 .\" above copyright notice and this permission notice appear in all  .\" copyright notice and this permission notice appear in all copies.
 .\" copies.  
 .\"  .\"
 .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL  .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 .\" WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED  .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 .\" WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE  .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 .\" AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL  .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 .\" DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR  .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 .\" PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER  .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR  .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\" PERFORMANCE OF THIS SOFTWARE.  .\"
 .\"  
 .Dd $Mdocdate$  .Dd $Mdocdate$
 .Dt MDOC 7  .Dt MDOC 7
 .Os  .Os
 .\" SECTION  
 .Sh NAME  .Sh NAME
 .Nm mdoc  .Nm mdoc
 .Nd mdoc language reference  .Nd mdoc language reference
 .\" SECTION  
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm mdoc  .Nm mdoc
 language is used to format  language is used to format
 .Bx  .Bx
 .Ux  .Ux
 manuals.  In this reference document, we describe the syntax, ontology  manuals.  In this reference document, we describe its syntax, structure,
 and structure of the  and usage.  Our reference implementation is mandoc; the
 .Nm  .Sx COMPATIBILITY
 language.  section describes compatibility with other troff \-mdoc implementations.
 .\" PARAGRAPH  
 .Pp  .Pp
 An  An
 .Nm  .Nm
 document follows simple rules:  lines beginning with the control  document follows simple rules:  lines beginning with the control
 character  character
 .Sq \.  .Sq \.
 are parsed for macros.  Other lines are interpreted within the scope of  are parsed for macros.  Other lines are interpreted within the scope of
 prior macros:  prior macros:
 .Bd -literal -offset XXX  .Bd -literal -offset indent
 \&.Sh Macro lines change control state.  \&.Sh Macro lines change control state.
 Other lines are interpreted within the current state.  Other lines are interpreted within the current state.
 .Ed  .Ed
 .\" SECTION  .Sh LANGUAGE SYNTAX
 .Sh INPUT ENCODING  
 .Nm  .Nm
 documents may contain only graphable 7-bit ASCII characters, the space  documents may contain only graphable 7-bit ASCII characters, the space
 character  character, and, in certain circumstances, the tab character.  All
 .Sq \  ,  manuals must have
 and, in certain circumstances, the tab character  .Ux
 .Sq \et .  line terminators.
 All manuals must have  .Ss Comments
 .Sq \en  Text following a
 line termination.  .Sq \e" ,
 .Pp  whether in a macro or free-form text line, is ignored to the end of
 The only time a blank line is acceptable is within  line.  A macro line with only a control character and comment escape,
 the context of  .Sq \&.\e" ,
 .Sq \&.Bd \-literal  is also ignored.  Macro lines with only a control charater and optionally
 or  whitespace are stripped from input.
 .Sq \&.Bd \-unfilled .  
 .Pp  
 Tab characters  
 .Pq \et  
 are only acceptable when delimiting  
 .Sq \&.Bl \-column  
 and in  
 .Sq \&.Bd \-literal  
 or  
 .Sq \&.Bd \-unfilled  
 contexts.  
 .\" SUB-SECTION  
 .Ss Reserved Characters  .Ss Reserved Characters
 Within a macro line, the following characters are reserved:  Within a macro line, the following characters are reserved:
 .Bl -tag -width 12n -offset XXXX -compact  .Pp
   .Bl -tag -width Ds -offset indent -compact
 .It \&.  .It \&.
 .Pq period  .Pq period
 .It \&,  .It \&,
Line 97  Within a macro line, the following characters are rese
Line 80  Within a macro line, the following characters are rese
 .It \&?  .It \&?
 .Pq question  .Pq question
 .It \&!  .It \&!
 .Pq exclamation  .Pq exclamation
   .It \&|
   .Pq vertical bar
 .El  .El
 .\" PARAGRAPH  
 .Pp  .Pp
 Use of reserved characters is described in  Use of reserved characters is described in
 .Sx Closure .  .Sx MACRO SYNTAX .
 For general non-reserved use, characters must either be escaped with a  For general use in macro lines, these characters must either be escaped
 non-breaking space  with a non-breaking space
 .Pq Sq \e&  .Pq Sq \e&
 or, if applicable, an appropriate escape-sequence used.  or, if applicable, an appropriate escape sequence used.
 .\" SUB-SECTION  
 .Ss Special Characters  .Ss Special Characters
 Special character sequences begin with the escape character  Special characters may occur in both macro and free-form lines.
   Sequences begin with the escape character
 .Sq \e  .Sq \e
 followed by either an open-parenthesis  followed by either an open-parenthesis
 .Sq \&(  .Sq \&(
 for two-character sequences; an open-bracket  for two-character sequences; an open-bracket
 .Sq \&[  .Sq \&[
 for n-character sequences (terminated at a close-bracket  for n-character sequences (terminated at a close-bracket
 .Sq \&] ) ;  .Sq \&] ) ;
 or a single one-character sequence.  or a single one-character sequence.
   See
   .Xr mandoc_char 7
   for a complete list.
   Examples include
   .Sq \e(em
   .Pq em-dash
   and
   .Sq \ee
   .Pq back-slash .
   .Ss Text Decoration
   Terms may be text-decorated using the
   .Sq \ef
   escape followed by an indicator: B (bold), I, (italic), R (Roman), or P
   (revert to previous mode):
 .Pp  .Pp
 Characters may alternatively be escaped by a slash-asterisk,  .D1 \efBbold\efR \efIitalic\efP
 .Sq \e* ,  
 with the same combinations as described above.  This form is deprecated.  
 .\" SECTION  
 .Sh STRUCTURE  
 Macros are classified in an ontology described by their scope rules.  
 Some macros are allowed to deviate from their classifications to  
 preserve backward-compatibility with old macro combinations still found  
 in the manual corpus.  These are specifically noted on a per-macro  
 basis.  
 .\" SUB-SECTION  
 .Ss Scope  
 .Bl -inset  
 .\" LIST-ITEM  
 .It Em Block  
 macros enclose other block macros, in-line macros or text, and  
 may span multiple lines.  
 .Bl -inset -offset XXXX  
 .\" LIST-ITEM  
 .It Em Full-block  
 macros always span multiple lines.  They consist of zero or  
 more  
 .Qq heads ,  
 subsequent macros or text on the same line following invocation; an  
 optional  
 .Qq body ,  
 which spans subsequent lines of text or macros; and an optional  
 .Qq tail ,  
 macros or text on the same line following closure.  
 .\" LIST-ITEM  
 .It Em Partial-block  
 macros may span multiple lines.  They consists of a optional  
 .Qq head ,  
 text immediately following invocation; always a  
 .Qq body ,  
 text or macros following the head on the same and subsequent lines; and  
 optionally a  
 .Qq tail ,  
 text immediately following closure.  
 .\" LIST-ITEM  
 .It Em In-line  
 macros may only enclose text and span at most a single line.  
 .El  
 .El  
 .\" SUB-SECTION  
 .Ss Closure  
 Closure of a macro's scope depends first on its classification, then  
 on whether it's parsable.  In this table,  
 .Sq BFE  
 refers to block full-explicit and so on.  
 .\" PARAGRAPH  
 .Pp  .Pp
 .Bl -tag -width 12n -offset XXXX -compact  A numerical representation 3, 2, or 1 (bold, italic, and Roman,
 .It BPE , BFE  respectively) may be used instead.
 corresponding explicit closure macro  A text decoration is valid within
 .It BFI  the current font scope only:  if a macro opens a font scope alongside
 end-of-file or a corresponding implicit closure macro  its own scope, such as
 .It BPI  .Sx \&Bf
 end-of-line (body may be closed by >0 space-separated  .Cm \&Sy ,
 .Sx Reserved Characters ,  in-scope invocations of
 although block scope will still be open)  .Sq \ef
 .It INL  are only valid within the font scope of the macro.
 end-of-line  If
 .El  .Sq \ef
 .\" PARAGRAPH  is specified outside of any font scope, such as in unenclosed, free-form
   text, it will affect the remainder of the document.
 .Pp  .Pp
 If a macro (block or in-line) is parsable, it may also be closed out by  Text may also be sized with the
 one of the following scenarios (unless specifically noted otherwise):  .Sq \es
 .\" PARAGRAPH  escape, whose syntax is one of
   .Sq \es+-n
   for one-digit numerals;
   .Sq \es(+-nn
   or
   .Sq \es+-(nn
   for two-digit numerals; and
   .Sq \es[+-N] ,
   .Sq \es+-[N] ,
   .Sq \es'+-N' ,
   or
   .Sq \es+-'N'
   for arbitrary-digit numerals:
 .Pp  .Pp
 .Bl -dash -offset XXXX -compact  .D1 \es+1bigger\es-1
 .It  .D1 \es[+10]much bigger\es[-10]
 a sequence of >0 space-separated  .D1 \es+(10much bigger\es-(10
 .Sx Reserved Characters ,  .D1 \es+'100'much much bigger\es-'100'
 .It  .Pp
 another macro,  Note these forms are
 .It  .Em not
 end-of-line, or  recommended for
 .It  .Nm ,
 completion of a set number of arguments.  which encourages semantic annotation.
   .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
   Whitespace consists of the space character.
   In free-form lines, whitespace is preserved within a line; un-escaped
   trailing spaces are stripped from input (unless in a literal context).
   Blank free-form lines, which may include whitespace, are only permitted
   within literal contexts.
   .Pp
   In macro lines, whitespace delimits arguments and is discarded.
   If arguments are quoted, whitespace within the quotes is retained.
   .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
   There are several macros in
   .Nm
   that require a date argument.
   The canonical form for dates is the American format:
   .Pp
   .D1 Cm Month Day , Year
   .Pp
   The
   .Cm Day
   value is an optionally zero-padded numeral.
   The
   .Cm Month
   value is the full month name.
   The
   .Cm Year
   value is the full four-digit year.
   .Pp
   Reduced form dates are broken-down canonical form dates:
   .Pp
   .D1 Cm Month , Year
   .D1 Cm Year
   .Pp
   Some examples of valid dates follow:
   .Pp
   .D1 "May, 2009" Pq reduced form
   .D1 "2009" Pq reduced form
   .D1 "May 20, 2009" Pq canonical form
   .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  .El
 .\" PARAGRAPH  
 .Pp  .Pp
 If >0 space-separated  Using anything other than
 .Sx Reserved Characters  .Sq m ,
 are followed by non-reserved characters, the behaviour differs per  .Sq n ,
 macro.  In general, scope of the macro is closed and re-opened:  .Sq u ,
 subsequent tokens are interpreted as if the scope had just been opened.  or
 In other circumstances, scope is simply closed out.  .Sq v
 .\" SECTION  is necessarily non-portable across output media.
 .Sh SYNTAX  See
 Macros are two or three characters in length.  The syntax of macro  .Sx COMPATIBILITY .
 invocation depends on its classification.  .Ss Sentence Spacing
 .Qq \-arg  When composing a manual, make sure that your sentences end at the end of
 refers to the macro arguments (which may contain zero or more values).  a line.
 In these illustrations,  By doing so, front-ends will be able to apply the proper amount of
 .Sq \&.Yo  spacing after the end of sentence (unescaped) period, exclamation mark,
 opens the scope of a macro, and if specified,  or question mark followed by zero or more non-sentence closing
 .Sq \&.Yc  delimiters (
 closes it out (closure may be implicit at end-of-line or end-of-file).  .Ns Sq \&) ,
 .\" PARAGRAPH  .Sq \&] ,
   .Sq \&' ,
   .Sq \&" ) .
 .Pp  .Pp
 Block full-explicit (may contain head, body, tail).  The proper spacing is also intelligently preserved if a sentence ends at
 .Bd -literal -offset XXXX  the boundary of a macro line, e.g.,
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB  .Pp
 \(lBbody...\(rB  .D1 \&Xr mandoc 1 \.
 \&.Yc \(lBtail...\(rB  .D1 \&Fl T \&Ns \&Cm ascii \.
   .Sh MANUAL STRUCTURE
   A well-formed
   .Nm
   document consists of a document prologue followed by one or more
   sections.
   .Pp
   The prologue, which consists of (in order) the
   .Sx \&Dd ,
   .Sx \&Dt ,
   and
   .Sx \&Os
   macros, 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
   followed by
   .Sx \&Nd .
   .Pp
   Following that, convention dictates specifying at least the SYNOPSIS and
   DESCRIPTION sections, although this varies between manual sections.
   .Pp
   The following is a well-formed skeleton
   .Nm
   file:
   .Bd -literal -offset indent
   \&.Dd $\&Mdocdate$
   \&.Dt mdoc 7
   \&.Os
   \&.
   \&.Sh NAME
   \&.Nm foo
   \&.Nd a description goes here
   \&.\e\*q The next is for sections 2, 3, & 9 only.
   \&.\e\*q .Sh LIBRARY
   \&.
   \&.Sh SYNOPSIS
   \&.Nm foo
   \&.Op Fl options
   \&.Ar
   \&.
   \&.Sh DESCRIPTION
   The
   \&.Nm
   utility processes files ...
   \&.\e\*q .Sh IMPLEMENTATION NOTES
   \&.\e\*q The next is for sections 2, 3, & 9 only.
   \&.\e\*q .Sh RETURN VALUES
   \&.\e\*q The next is for sections 1, 6, 7, & 8 only.
   \&.\e\*q .Sh ENVIRONMENT
   \&.\e\*q .Sh FILES
   \&.\e\*q The next is for sections 1 & 8 only.
   \&.\e\*q .Sh EXIT STATUS
   \&.\e\*q .Sh EXAMPLES
   \&.\e\*q The next is for sections 1, 4, 6, 7, & 8 only.
   \&.\e\*q .Sh DIAGNOSTICS
   \&.\e\*q The next is for sections 2, 3, & 9 only.
   \&.\e\*q .Sh ERRORS
   \&.\e\*q .Sh SEE ALSO
   \&.\e\*q .Xr foobar 1
   \&.\e\*q .Sh STANDARDS
   \&.\e\*q .Sh HISTORY
   \&.\e\*q .Sh AUTHORS
   \&.\e\*q .Sh CAVEATS
   \&.\e\*q .Sh BUGS
   \&.\e\*q .Sh SECURITY CONSIDERATIONS
 .Ed  .Ed
 .\" PARAGRAPH  
 .Pp  .Pp
 Block full-implicit (may contain zero or more heads, body, no tail).  The sections in a
 .Bd -literal -offset XXXX  .Nm
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB  document are conventionally ordered as they appear above.
 \(lBbody...\(rB  Sections should be composed as follows:
 \&.Yc  .Bl -ohang -offset Ds
   .It Em NAME
   The name(s) and a short description of the documented material.
   The syntax for this as follows:
   .Bd -literal -offset indent
   \&.Nm name0
   \&.Nm name1
   \&.Nm name2
   \&.Nd a short description
 .Ed  .Ed
 .\" PARAGRAPH  
 .Pp  .Pp
 Block partial-explicit (may contain head, multi-line body, tail).  The
 .Bd -literal -offset XXXX  .Sx \&Nm
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB  macro(s) must precede the
 \(lBbody...\(rB  .Sx \&Nd
 \&.Yc \(lBtail...\(rB  macro.
   .Pp
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBhead...\(rB \  See
 \(lBbody...\(rB \&Yc \(lBtail...\(rB  .Sx \&Nm
   and
   .Sx \&Nd .
   .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  .Ed
 .\" PARAGRAPH  
 .Pp  .Pp
 Block partial-implicit (no head, body, no tail).  Note that the body  See
 section may be followed by zero or more  .Sx \&Lb .
 .Sx Reserved Words .  .It Em SYNOPSIS
 These are in the block scope, but not in the body scope.  Documents the utility invocation syntax, function call syntax, or device
 .Bd -literal -offset XXXX  configuration.
 \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBreserved...\(rB  .Pp
   For the first, utilities (sections 1, 6, and 8), this is
   generally structured as follows:
   .Bd -literal -offset indent
   \&.Nm foo
   \&.Op Fl v
   \&.Op Fl o Ar file
   \&.Op Ar
   \&.Nm bar
   \&.Op Fl v
   \&.Op Fl o Ar file
   \&.Op Ar
 .Ed  .Ed
 .\" PARAGRAPH  
 .Pp  .Pp
 In-lines have \(>=0 scoped arguments.  For the second, function calls (sections 2, 3, 9):
 .Bd -literal -offset XXX  .Bd -literal -offset indent
 \&.Yy \(lB\-arg \(lBval...\(rB\(rB \(lBargs...\(rB  \&.Vt extern const char *global;
   \&.In header.h
 \&.Yy \(lB\-arg \(lBval...\(rB\(rB arg0 arg1 argN  \&.Ft "char *"
   \&.Fn foo "const char *src"
   \&.Ft "char *"
   \&.Fn bar "const char *src"
 .Ed  .Ed
 .\"  .Pp
 .Sh MACROS  And for the third, configurations (section 4):
 This section contains a complete list of all  .Bd -literal -offset indent
 .Nm  \&.Cd \*qit* at isa? port 0x2e\*q
 macros, arranged ontologically.  A  \&.Cd \*qit* at isa? port 0x4e\*q
 .Qq callable  .Ed
 macro is invoked subsequent to the initial macro-line macro.  A  .Pp
 .Qq parsable  Manuals not in these sections generally don't need a
 macro may be followed by further (ostensibly callable) macros.  .Em SYNOPSIS .
 .\" SUB-SECTION  .Pp
   See
   .Sx \&Op ,
   .Sx \&Cd ,
   .Sx \&Fn ,
   .Sx \&Ft ,
   and
   .Sx \&Vt .
   .It Em DESCRIPTION
   This expands upon the brief, one-line description in
   .Em NAME .
   It usually contains a break-down of the options (if documenting a
   command), such as:
   .Bd -literal -offset indent
   The arguments are as follows:
   \&.Bl \-tag \-width Ds
   \&.It Fl v
   Print verbose information.
   \&.El
   .Ed
   .Pp
   Manuals not documenting a command won't include the above fragment.
   .It Em IMPLEMENTATION NOTES
   Implementation-specific notes should be kept here.
   This is useful when implementing standard functions that may have side
   effects or notable algorithmic implications.
   .It Em RETURN VALUES
   This section is the dual of
   .Em EXIT STATUS ,
   which is used for commands.
   It documents the return values of functions in sections 2, 3, and 9.
   .Pp
   See
   .Sx \&Rv .
   .It Em ENVIRONMENT
   Documents any usages of environment variables, e.g.,
   .Xr environ 7 .
   .Pp
   See
   .Sx \&Ev .
   .It Em FILES
   Documents files used.
   It's helpful to document both the file and a short description of how
   the file is used (created, modified, etc.).
   .Pp
   See
   .Sx \&Pa .
   .It Em EXIT STATUS
   Command exit status for section 1, 6, and 8 manuals.
   This section is the dual of
   .Em RETURN VALUES ,
   which is used for functions.
   Historically, this information was described in
   .Em DIAGNOSTICS ,
   a practise that is now discouraged.
   .Pp
   See
   .Sx \&Ex .
   .It Em EXAMPLES
   Example usages.
   This often contains snippets of well-formed, well-tested invocations.
   Make doubly sure that your examples work properly!
   .It Em DIAGNOSTICS
   Documents error conditions.
   This is most useful in section 4 manuals.
   Historically, this section was used in place of
   .Em EXIT STATUS
   for manuals in sections 1, 6, and 8; however, this practise is
   discouraged.
   .Pp
   See
   .Sx \&Bl
   .Fl diag .
   .It Em ERRORS
   Documents error handling in sections 2, 3, and 9.
   .Pp
   See
   .Sx \&Er .
   .It Em SEE ALSO
   References other manuals with related topics.
   This section should exist for most manuals.
   Cross-references should conventionally be ordered first by section, then
   alphabetically.
   .Pp
   See
   .Sx \&Xr .
   .It Em STANDARDS
   References any standards implemented or used.
   If not adhering to any standards, the
   .Em HISTORY
   section should be used instead.
   .Pp
   See
   .Sx \&St .
   .It Em HISTORY
   The history of any manual without a
   .Em STANDARDS
   section should be described in this section.
   .It Em AUTHORS
   Credits to authors, if applicable, should appear in this section.
   Authors should generally be noted by both name and an e-mail address.
   .Pp
   See
   .Sx \&An .
   .It Em CAVEATS
   Explanations of common misuses and misunderstandings should be explained
   in this section.
   .It Em BUGS
   Extant bugs should be described in this section.
   .It Em SECURITY CONSIDERATIONS
   Documents any security precautions that operators should consider.
   .El
   .Sh MACRO SYNTAX
   Macros are one to three three characters in length and begin with a
   control character ,
   .Sq \&. ,
   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
   \&.Pp
   \&.\ \ \ \&Pp
   .Ed
   .Pp
   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 be called subsequent to the initial
   line-macro.
   If a macro is not callable, then its invocation after the initial line
   macro is interpreted as opaque text, such that
   .Sq \&.Fl \&Sh
   produces
   .Sq Fl \&Sh .
   .Pp
   The
   .Em Parsable
   column indicates whether the macro may be followed by further
   (ostensibly callable) macros.
   If a macro is not parsable, subsequent macro invocations on the line
   will be 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
   contains a head.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead...\(rB
   \(lBbody...\(rB
   \&.Yc
   .Ed
   .Pp
   .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXX"
   .It Em Macro Ta Em Callable Ta Em Parsable 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  .Ss Block full-implicit
 The head of these macros follows invocation; the body is the content of  Multi-line scope closed by end-of-file or implicitly by another macro.
 subsequent lines prior to closure.  None of these macros have tails;  All macros have bodies; some
 some  
 .Po  .Po
 .Sq \&.It \-bullet ,  .Sx \&It Fl bullet ,
 .Sq \-hyphen ,  .Fl hyphen ,
 .Sq \-dash ,  .Fl dash ,
 .Sq \-enum ,  .Fl enum ,
 .Sq \-item  .Fl item
 .Pc  .Pc
 don't have heads.  don't have heads; only one
   .Po
   .Sx \&It Fl column
   .Pc
   has multiple heads.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBparm...\(rB\(rB \(lBhead... \(lBTa head...\(rB\(rB
   \(lBbody...\(rB
   .Ed
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "Closing" -compact -offset XXXX  .Bl -column -compact -offset indent "MacroX" "CallableX" "ParsableX" "closed by XXXXXXXXXXX"
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Closing  .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
 .It \&.Sh    Ta    \&No    Ta    \&No    Ta    \&.Sh  .It Sx \&It  Ta    \&No     Ta    Yes      Ta    closed by Sx \&It , Sx \&El
 .It \&.Ss    Ta    \&No    Ta    \&No    Ta    \&.Sh, \&.Ss  .It Sx \&Nd  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh
 .It \&.It    Ta    \&No    Ta    Yes     Ta    \&.It, \&.El  .It Sx \&Sh  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh
   .It Sx \&Ss  Ta    \&No     Ta    \&No     Ta    closed by Sx \&Sh , Sx \&Ss
 .El  .El
 .\" SUB-SECTION  .Ss Block partial-explicit
 .Ss Block full-explicit  Like block full-explicit, but also with single-line scope.
 None of these macros are callable or parsed.  The last column indicates  Each has at least a body and, in limited circumstances, a head
 the explicit scope rules.  All contains bodies, some may contain heads  .Po
 .Pq So \&Bf Sc .  .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
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXX" -compact -offset XXXX  .Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset indent
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope
 .It \&.Bd    Ta    \&No    Ta    \&No    Ta    closed by \&.Ed  .It Sx \&Ac  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Ao
 .It \&.Ed    Ta    \&No    Ta    \&No    Ta    opened by \&.Bd  .It Sx \&Ao  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Ac
 .It \&.Bl    Ta    \&No    Ta    \&No    Ta    closed by \&.El  .It Sx \&Bc  Ta    Yes      Ta    Yes      Ta    closed by Sx \&Bo
 .It \&.El    Ta    \&No    Ta    \&No    Ta    opened by \&.Bl  .It Sx \&Bo  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bc
 .It \&.Bf    Ta    \&No    Ta    \&No    Ta    closed by \&.Ef  .It Sx \&Brc Ta    Yes      Ta    Yes      Ta    opened by Sx \&Bro
 .It \&.Ef    Ta    \&No    Ta    \&No    Ta    opened by \&.Bf  .It Sx \&Bro Ta    Yes      Ta    Yes      Ta    closed by Sx \&Brc
 .It \&.Bk    Ta    \&No    Ta    \&No    Ta    closed by \&.Ek  .It Sx \&Dc  Ta    Yes      Ta    Yes      Ta    opened by Sx \&Do
 .It \&.Ek    Ta    \&No    Ta    \&No    Ta    opened by \&.Bk  .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  .El
 .\" SUB-SECTION  
 .Ss Block partial-implicit  .Ss Block partial-implicit
 All of these are callable and parsed for further macros.  Their scopes  Like block full-implicit, but with single-line scope closed by
 close at the invocation's end-of-line.  .Sx Reserved Characters
   or end of line.
   .Bd -literal -offset indent
   \&.Yo \(lB\-arg \(lBval...\(rB\(rB \(lBbody...\(rB \(lBres...\(rB
   .Ed
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset XXXX  .Bl -column "MacroX" "CallableX" "ParsableX" -compact -offset indent
 .It Em Macro Ta Em Callable Ta Em Parsable  .It Em Macro Ta Em Callable Ta Em Parsable
 .It \&.Aq    Ta    Yes   Ta    Yes  .It Sx \&Aq  Ta    Yes      Ta    Yes
 .It \&.Op    Ta    Yes   Ta    Yes  .It Sx \&Bq  Ta    Yes      Ta    Yes
 .It \&.Bq    Ta    Yes   Ta    Yes  .It Sx \&Brq Ta    Yes      Ta    Yes
 .It \&.Dq    Ta    Yes   Ta    Yes  .It Sx \&D1  Ta    \&No     Ta    \&Yes
 .It \&.Pq    Ta    Yes   Ta    Yes  .It Sx \&Dl  Ta    \&No     Ta    Yes
 .It \&.Qq    Ta    Yes   Ta    Yes  .It Sx \&Dq  Ta    Yes      Ta    Yes
 .It \&.Sq    Ta    Yes   Ta    Yes  .It Sx \&Op  Ta    Yes      Ta    Yes
 .It \&.Brq   Ta    Yes   Ta    Yes  .It Sx \&Pq  Ta    Yes      Ta    Yes
 .It \&.D1    Ta    \&No  Ta    \&Yes  .It Sx \&Ql  Ta    Yes      Ta    Yes
 .It \&.Dl    Ta    \&No  Ta    Yes  .It Sx \&Qq  Ta    Yes      Ta    Yes
 .It \&.Ql    Ta    Yes   Ta    Yes  .It Sx \&Sq  Ta    Yes      Ta    Yes
   .It Sx \&Vt  Ta    Yes      Ta    Yes
 .El  .El
 .\" PARAGRAPH  
 .Pp  .Pp
 The  Note that the
 .Sq \&.Op  .Sx \&Vt
 may be broken by  macro is a
 .Sq \&.Oc  .Sx Block partial-implicit
 as in the following example:  only when invoked as the first macro
 .Bd -literal -offset XXXX  in a
 \&.Oo  .Em SYNOPSIS
 \&.Op Fl a Oc  section line, else it is
   .Sx In-line .
   .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
   \&.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  .Ed
 .Pp  .Pp
 In the above example, the scope of  .Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset indent
 .Sq \&.Op  .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments
 is technically broken by  .It Sx \&%A  Ta    \&No     Ta    \&No     Ta    >0
 .Sq \&.Oc ,  .It Sx \&%B  Ta    \&No     Ta    \&No     Ta    >0
 however, due to the overwhelming existence of this sequence, it's  .It Sx \&%C  Ta    \&No     Ta    \&No     Ta    >0
 allowed.  .It Sx \&%D  Ta    \&No     Ta    \&No     Ta    >0
 .\" SUB-SECTION  .It Sx \&%I  Ta    \&No     Ta    \&No     Ta    >0
 .Ss Block partial-explicit  .It Sx \&%J  Ta    \&No     Ta    \&No     Ta    >0
 Each of these contains at least a body and, in limited circumstances, a  .It Sx \&%N  Ta    \&No     Ta    \&No     Ta    >0
 head  .It Sx \&%O  Ta    \&No     Ta    \&No     Ta    >0
 .Pq So \&.Fo Sc , So \&.Eo Sc  .It Sx \&%P  Ta    \&No     Ta    \&No     Ta    >0
 and/or tail  .It Sx \&%Q  Ta    \&No     Ta    \&No     Ta    >0
 .Pq So \&.Ec Sc .  .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    n
   .It Sx \&An  Ta    Yes      Ta    Yes      Ta    n
   .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    n
   .It Sx \&Db  Ta    \&No     Ta    \&No     Ta    1
   .It Sx \&Dd  Ta    \&No     Ta    \&No     Ta    >0
   .It Sx \&Dt  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Dv  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Dx  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Em  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&En  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Er  Ta    Yes      Ta    Yes      Ta    >0
   .It Sx \&Es  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&Ev  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Ex  Ta    \&No     Ta    \&No     Ta    n
   .It Sx \&Fa  Ta    Yes      Ta    Yes      Ta    n
   .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    \&No     Ta    \&No     Ta    n
   .It Sx \&Ft  Ta    Yes      Ta    Yes      Ta    n
   .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    n
   .It Sx \&Lb  Ta    \&No     Ta    \&No     Ta    1
   .It Sx \&Li  Ta    Yes      Ta    Yes      Ta    n
   .It Sx \&Lk  Ta    Yes      Ta    Yes      Ta    n
   .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    \&No     Ta    \&No     Ta    n
   .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    1
   .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    >0
   .It Sx \&br  Ta    \&No     Ta    \&No     Ta    0
   .It Sx \&sp  Ta    \&No     Ta    \&No     Ta    1
   .El
   .Sh REFERENCE
   This section is a canonical reference of all macros, arranged
   alphabetically.
   For the scoping of individual macros, see
   .Sx MACRO SYNTAX .
   .Ss \&%A
   Author name of an
   .Sx \&Rs
   block.  Multiple authors should each be accorded their own
   .Sx \%%A
   line.  Author names should be ordered with full or abbreviated
   forename(s) first, then full surname.
   .Ss \&%B
   Book title of an
   .Sx \&Rs
   block.  This macro may also be used in a non-bibliographic context when
   referring to book titles.
   .Ss \&%C
   Publication city or location of an
   .Sx \&Rs
   block.
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "closed by XXXX" -compact -offset XXXX  .Em Remarks :
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Scope  this macro is not implemented in
 .It \&.Ao    Ta    Yes   Ta    Yes    Ta    closed by \&.Ac  .Xr groff 1 .
 .It \&.Ac    Ta    Yes   Ta    Yes    Ta    opened by \&.Ao  .Ss \&%D
 .It \&.Bc    Ta    Yes   Ta    Yes    Ta    closed by \&.Bo  Publication date of an
 .It \&.Bo    Ta    Yes   Ta    Yes    Ta    opened by \&.Bc  .Sx \&Rs
 .It \&.Pc    Ta    Yes   Ta    Yes    Ta    closed by \&.Po  block.  This should follow the reduced or canonical form syntax
 .It \&.Po    Ta    Yes   Ta    Yes    Ta    opened by \&.Pc  described in
 .It \&.Do    Ta    Yes   Ta    Yes    Ta    closed by \&.Dc  .Sx Dates .
 .It \&.Dc    Ta    Yes   Ta    Yes    Ta    opened by \&.Do  .Ss \&%I
 .It \&.Xo    Ta    Yes   Ta    Yes    Ta    closed by \&.Xc  Publisher or issuer name of an
 .It \&.Xc    Ta    Yes   Ta    Yes    Ta    opened by \&.Xo  .Sx \&Rs
 .It \&.Bro   Ta    Yes   Ta    Yes    Ta    closed by \&.Brc  block.
 .It \&.Brc   Ta    Yes   Ta    Yes    Ta    opened by \&.Bro  .Ss \&%J
 .It \&.Oc    Ta    Yes   Ta    Yes    Ta    closed by \&.Oo  Journal name of an
 .It \&.Oo    Ta    Yes   Ta    Yes    Ta    opened by \&.Oc  .Sx \&Rs
 .It \&.So    Ta    Yes   Ta    Yes    Ta    closed by \&.Sc  block.
 .It \&.Sc    Ta    Yes   Ta    Yes    Ta    opened by \&.So  .Ss \&%N
 .It \&.Fc    Ta    Yes   Ta    Yes    Ta    opened by \&.Fo  Issue number (usually for journals) of an
 .It \&.Fo    Ta    \&No  Ta    \&No   Ta    closed by \&.Fc  .Sx \&Rs
 .It \&.Ec    Ta    Yes   Ta    Yes    Ta    opened by \&.Eo  block.
 .It \&.Eo    Ta    Yes   Ta    Yes    Ta    closed by \&.Ec  .Ss \&%O
 .It \&.Qc    Ta    Yes   Ta    Yes    Ta    opened by \&.Oo  Optional information of an
 .It \&.Qo    Ta    Yes   Ta    Yes    Ta    closed by \&.Oc  .Sx \&Rs
 .It \&.Re    Ta    \&No  Ta    \&No   Ta    opened by \&.Rs  block.
 .It \&.Rs    Ta    \&No  Ta    \&No   Ta    closed by \&.Re  .Ss \&%P
   Book or journal page number of an
   .Sx \&Rs
   block.
   .Ss \&%Q
   Institutional author (school, government, etc.) of an
   .Sx \&Rs
   block.  Multiple institutional authors should each be accorded their own
   .Sx \&%Q
   line.
   .Ss \&%R
   Technical report name of an
   .Sx \&Rs
   block.
   .Ss \&%T
   Article title of an
   .Sx \&Rs
   block.  This macro may also be used in a non-bibliographical context
   when referring to article titles.
   .Ss \&%U
   URI of reference document.
   .Ss \&%V
   Volume number of an
   .Sx \&Rs
   block.
   .Ss \&Ac
   Closes an
   .Sx \&Ao
   block.  Does not have any tail arguments.
   .Ss \&Ad
   Address construct: usually in the context of an computational address in
   memory, not a physical (post) address.
   .Pp
   Examples:
   .D1 \&.Ad [0,$]
   .D1 \&.Ad 0x00000000
   .Ss \&An
   Author name.
   This macro may alternatively accepts the following arguments, although
   these may not be specified along with a parameter:
   .Bl -tag -width 12n -offset indent
   .It Fl split
   Renders a line break before each author listing.
   .It Fl nosplit
   The opposite of
   .Fl split .
 .El  .El
 .\" SUB-SECTION  
 .Ss In-line  
 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.  
 .Pp  .Pp
 .Bl -column "MacroX" "CallableX" "ParsableX" "Arguments" -compact -offset XXXX  In the AUTHORS section, the default is not to split the first author
 .It Em Macro Ta Em Callable Ta Em Parsable Ta Em Arguments  listing, but all subsequent author listings, whether or not they're
 .It \&.Dd    Ta    \&No  Ta    \&No    Ta    >0  interspersed by other macros or text, are split.
 .It \&.Dt    Ta    \&No  Ta    \&No    Ta    n  Thus, specifying
 .It \&.Os    Ta    \&No  Ta    \&No    Ta    n  .Fl split
 .It \&.Pp    Ta    \&No  Ta    \&No    Ta    0  will cause the first listing also to be split.
 .It \&.Ad    Ta    Yes   Ta    Yes     Ta    n  If not in the AUTHORS section, the default is not to split.
 .It \&.An    Ta    \&No  Ta    Yes     Ta    n  .Pp
 .It \&.Ar    Ta    Yes   Ta    Yes     Ta    n  Examples:
 .It \&.Cd    Ta    Yes   Ta    \&No    Ta    >0  .D1 \&.An -nosplit
 .It \&.Cm    Ta    Yes   Ta    Yes     Ta    n  .D1 \&.An J. D. Ullman .
 .It \&.Dv    Ta    Yes   Ta    Yes     Ta    n  .Pp
 .It \&.Er    Ta    Yes   Ta    Yes     Ta    >0  .Em Remarks :
 .It \&.Ev    Ta    Yes   Ta    Yes     Ta    n  the effects of
 .It \&.Ex    Ta    \&No  Ta    \&No    Ta    0  .Fl split
 .It \&.Fa    Ta    Yes   Ta    Yes     Ta    n  or
 .It \&.Fd    Ta    \&No  Ta    \&No    Ta    >0  .Fl nosplit
 .It \&.Fl    Ta    Yes   Ta    Yes     Ta    n  are re-set when entering the AUTHORS section, so if one specifies
 .It \&.Fn    Ta    Yes   Ta    Yes     Ta    >0  .Sx \&An Fl nosplit
 .It \&.Ft    Ta    \&No  Ta    Yes     Ta    n  in the general document body, it must be re-specified in the AUTHORS
 .It \&.Ic    Ta    Yes   Ta    Yes     Ta    >0  section.
 .It \&.In    Ta    \&No  Ta    \&No    Ta    n  .Ss \&Ao
 .It \&.Li    Ta    Yes   Ta    Yes     Ta    n  Begins a block enclosed by angled brackets.
 .It \&.Nd    Ta    \&No  Ta    \&No    Ta    n  Does not have any head arguments.
 .It \&.Nm    Ta    Yes   Ta    Yes     Ta    n  .Pp
 .It \&.Ot    Ta    \&No  Ta    \&No    Ta    n  Examples:
 .It \&.Pa    Ta    Yes   Ta    Yes     Ta    n  .D1 \&.Fl -key= \&Ns \&Ao \&Ar val \&Ac
 .It \&.Rv    Ta    \&No  Ta    \&No    Ta    0  .Pp
 .It \&.St    Ta    \&No  Ta    Yes     Ta    1  See also
 .It \&.Va    Ta    Yes   Ta    Yes     Ta    n  .Sx \&Aq .
 .It \&.Vt    Ta    Yes   Ta    Yes     Ta    >0  .Ss \&Ap
 .It \&.Xr    Ta    Yes   Ta    Yes     Ta    >0, <3  Inserts an apostrophe without any surrounding white-space.
 .It \&.%A    Ta    \&No  Ta    \&No    Ta    >0  This is generally used as a grammatic device when referring to the verb
 .It \&.%B    Ta    \&No  Ta    \&No    Ta    >0  form of a function:
 .It \&.%C    Ta    \&No  Ta    \&No    Ta    >0  .Bd -literal -offset indent
 .It \&.%D    Ta    \&No  Ta    \&No    Ta    >0  \&.Fn execve Ap d
 .It \&.%I    Ta    \&No  Ta    \&No    Ta    >0  .Ed
 .It \&.%J    Ta    \&No  Ta    \&No    Ta    >0  .Ss \&Aq
 .It \&.%N    Ta    \&No  Ta    \&No    Ta    >0  Encloses its arguments in angled brackets.
 .It \&.%O    Ta    \&No  Ta    \&No    Ta    >0  .Pp
 .It \&.%P    Ta    \&No  Ta    \&No    Ta    >0  Examples:
 .It \&.%R    Ta    \&No  Ta    \&No    Ta    >0  .D1 \&.Fl -key= \&Ns \&Aq \&Ar val
 .It \&.%T    Ta    \&No  Ta    \&No    Ta    >0  .Pp
 .It \&.%V    Ta    \&No  Ta    \&No    Ta    >0  .Em Remarks :
 .It \&.At    Ta    Yes   Ta    Yes     Ta    1  this macro is often abused for rendering URIs, which should instead use
 .It \&.Bsx   Ta    Yes   Ta    Yes     Ta    n  .Sx \&Lk
 .It \&.Bx    Ta    Yes   Ta    Yes     Ta    n  or
 .It \&.Db    Ta    \&No  Ta    \&No    Ta    1  .Sx \&Mt ,
 .It \&.Em    Ta    Yes   Ta    Yes     Ta    >0  or to note pre-processor
 .It \&.Fx    Ta    Yes   Ta    Yes     Ta    n  .Dq Li #include
 .It \&.Ms    Ta    \&No  Ta    Yes     Ta    >0  statements, which should use
 .It \&.No    Ta    Yes   Ta    Yes     Ta    0  .Sx \&In .
 .It \&.Ns    Ta    Yes   Ta    Yes     Ta    0  .Pp
 .It \&.Nx    Ta    Yes   Ta    Yes     Ta    n  See also
 .It \&.Ox    Ta    Yes   Ta    Yes     Ta    n  .Sx \&Ao .
 .It \&.Pf    Ta    \&No  Ta    Yes     Ta    1  .Ss \&Ar
 .It \&.Sm    Ta    \&No  Ta    \&No    Ta    1  Command arguments.
 .It \&.Sx    Ta    Yes   Ta    Yes     Ta    >0  If an argument is not provided, the string
 .It \&.Sy    Ta    Yes   Ta    Yes     Ta    >0  .Dq file ...
 .It \&.Tn    Ta    Yes   Ta    Yes     Ta    >0  is used as a default.
 .It \&.Ux    Ta    Yes   Ta    Yes     Ta    n  .Pp
 .It \&.Dx    Ta    Yes   Ta    Yes     Ta    n  Examples:
 .It \&.Bt    Ta    \&No  Ta    \&No    Ta    0  .D1 \&.Fl o \&Ns \&Ar file1
 .It \&.Hf    Ta    \&No  Ta    \&No    Ta    n  .D1 \&.Ar
 .It \&.Fr    Ta    \&No  Ta    \&No    Ta    n  .D1 \&.Ar arg1 , arg2 .
 .It \&.Ud    Ta    \&No  Ta    \&No    Ta    0  .Ss \&At
 .It \&.Lb    Ta    \&No  Ta    \&No    Ta    1  Formats an AT&T version.
 .It \&.Ap    Ta    Yes   Ta    Yes     Ta    0  Accepts at most one parameter:
 .It \&.Lp    Ta    \&No  Ta    \&No    Ta    0  .Bl -tag -width 12n -offset indent
 .It \&.Lk    Ta    \&No  Ta    Yes     Ta    >0  .It Cm v[1-7] | 32v
 .It \&.Mt    Ta    \&No  Ta    Yes     Ta    >0  A version of
 .It \&.Es    Ta    \&No  Ta    \&No    Ta    0  .At .
 .It \&.En    Ta    \&No  Ta    \&No    Ta    0  .It Cm V[.[1-4]]?
   A system version of
   .At .
 .El  .El
 .Pp  .Pp
 The  Note that these parameters do not begin with a hyphen.
 .Sq \&.Ot ,  .Pp
 .Sq \&.Fr ,  Examples:
 .Sq \&.Es  .D1 \&.At
   .D1 \&.At V.1
   .Pp
   See also
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   .Sx \&Ox ,
 and  and
 .Sq \&.En ,  .Sx \&Ux .
 macros are obsolete.  .Ss \&Bc
 .\" SECTION  Closes a
 .Sh COMPATIBILITY  .Sx \&Bo
 The mdoc language was traditionally a  block.  Does not have any tail arguments.
 .Qq roff  .Ss \&Bd
 macro package; most existing manuals were written with mdoc syntax  Begins a display block.
 dictated by system-dependent roff installations.  This section documents  A display is collection of macros or text which may be collectively
 compatibility with these systems.  offset or justified in a manner different from that
   of the enclosing context.
   By default, the block is preceded by a vertical space.
 .Pp  .Pp
 .Bl -dash -compact  Each display is associated with a type, which must be one of the
 .\" LIST-ITEM  following arguments:
   .Bl -tag -width 12n -offset indent
   .It Fl ragged
   Only left-justify the block.
   .It Fl unfilled
   Do not justify the block at all.
   .It Fl filled
   Left- and right-justify the block.
   .It Fl literal
   Alias for
   .Fl unfilled .
   .It Fl centered
   Centre-justify each line.
   .El
   .Pp
   The type must be provided first.
   Secondary arguments are as follows:
   .Bl -tag -width 12n -offset indent
   .It Fl offset Ar width
   Offset by the value of
   .Ar width ,
   which is interpreted as one of the following, specified in order:
   .Bl -item
 .It  .It
 .Sq \&.Fo  As one of the pre-defined strings
 and  .Ar indent ,
 .Sq \&.St  the width of standard indentation;
 historically weren't always callable.  Both are now correctly callable.  .Ar indent-two ,
 .\" LIST-ITEM  twice
   .Ar indent ;
   .Ar left ,
   which has no effect ;
   .Ar right ,
   which justifies to the right margin; and
   .Ar center ,
   which aligns around an imagined centre axis.
 .It  .It
 .Sq \&.It \-nested  As a precalculated width for a named macro.
 is assumed for all lists: any list may be nested and  The most popular is the imaginary macro
 .Sq \-enum  .Ar \&Ds ,
 lists will restart the sequence only for the sub-list.  which resolves to
 .\" LIST-ITEM  .Ar 6n .
 .It  .It
 .Sq \&.It \-column  As a scaling unit following the syntax described in
 syntax where column widths may be preceeded by other arguments (instead  .Sx Scaling Widths .
 of proceeded) is not supported.  
 .\" LIST-ITEM  
 .It  .It
 The  As the calculated string length of the opaque string.
 .Sq \&.At  .El
 macro only accepts a single parameter.  .Pp
 .\" LIST-ITEM  If unset, it will revert to the value of
 .It  .Ar 8n
 The system-name macros (  as described in
 .Ns Sq \&.At ,  .Sx Scaling Widths .
 .Sq \&.Bsx ,  .It Fl compact
 .Sq \&.Bx ,  Do not assert a vertical space before the block.
 .Sq \&.Fx ,  .It Fl file Ar file
 .Sq \&.Nx ,  Prepend the file
 .Sq \&.Ox ,  .Ar file
   before any text or macros within the block.
   .El
   .Pp
   Examples:
   .Bd -literal -offset indent
   \&.Bd \-unfilled \-offset two-indent \-compact
      Hello       world.
   \&.Ed
   .Ed
   .Pp
   See also
   .Sx \&D1
 and  and
 .Sq \&.Ux )  .Sx \&Dl .
 are callable.  .Ss \&Bf
 .\" LIST-ITEM  .Ss \&Bk
 .It  .Ss \&Bl
 Some manuals use  Begins a list composed of one or more list entries.
 .Sq \&.Li  A list is associated with a type, which is a required argument.
 incorrectly by following it with a reserved character and expecting the  Other arguments are
 delimiter to render.  This is not supported.  .Fl width ,
 .\" LIST-ITEM  defined per-type as accepting a literal or
 .It  .Sx Scaling Widths
 .Sq \&.Cd  value;
 is callable.  .Fl offset ,
   also accepting a literal or
   .Sx Scaling Widths
   value setting the list's global offset; and
   .Fl compact ,
   suppressing the default vertical space printed before each list entry.
   A list entry is specified by the
   .Sx \&It
   macro, which consists of a head and optional body (depending on the list
   type).
   A list must specify one of the following list types:
   .Bl -tag -width 12n -offset indent
   .It Fl bullet
   A list offset by a bullet.
   The head of list entries must be empty.
   List entry bodies are positioned after the bullet.
   The
   .Fl width
   argument varies the width of list bodies' left-margins.
   .It Fl column
   A columnated list.
   The
   .Fl width
   argument has no effect.
   The number of columns is specified as parameters to the
   .Sx \&Bl
   macro.
   These dictate the width of columns either as
   .Sx Scaling Widths
   or literal text.
   List entry bodies must be left empty.
   Column bodies have the following syntax:
   .Pp
   .D1 .It col1 <TAB> ... coln
   .D1 .It col1 \&Ta ... coln
   .D1 .It col1 <TAB> col2 \&Ta coln
   .Pp
   where columns may be separated by tabs, the literal string
   .Qq \&Ta ,
   or a mixture of both.
   These are equivalent except that quoted sections propogate over tabs,
   for example,
   .Pp
   .D1 .It \(dqcol1 ; <TAB> col2 ;\(dq ;
   .Pp
   will preserve the semicolon whitespace except for the last.
   .It Fl dash
   A list offset by a dash (hyphen).
   The head of list entries must be empty.
   List entry bodies are positioned past the dash.
   The
   .Fl width
   argument varies the width of list bodies' left-margins.
   .It Fl diag
   Like
   .Fl inset ,
   but with additional formatting to the head.
   The
   .Fl width
   argument varies the width of list bodies' left-margins.
   .It Fl enum
   An enumerated list offset by the enumeration from 1.
   The head of list entries must be empty.
   List entry bodies are positioned after the enumeration.
   The
   .Fl width
   argument varies the width of list bodies' left-margins.
   .It Fl hang
   Like
   .Fl tag ,
   but instead of list bodies positioned after the head, they trail the
   head text.
   The
   .Fl width
   argument varies the width of list bodies' left-margins.
   .It Fl hyphen
   Synonym for
   .Fl dash .
   .It Fl inset
   List bodies follow the list head.
   The
   .Fl width
   argument is ignored.
   .It Fl item
   This produces blocks of text.
   The head of list entries must be empty.
   The
   .Fl width
   argument is ignored.
   .It Fl ohang
   List bodies are positioned on the line following the head.
   The
   .Fl width
   argument is ignored.
   .It Fl tag
   A list offset by list entry heads.  List entry bodies are positioned
   after the head as specified by the
   .Fl width
   argument.
 .El  .El
 .\" SECTION  .Ss \&Bo
 .Sh SEE ALSO  Begins a block enclosed by square brackets.
 .Xr mandoc 1 ,  Does not have any head arguments.
 .Xr mandoc_char 7  .Pp
 .\" SECTION  Examples:
 .Sh AUTHORS  .Bd -literal -offset indent
   \&.Bo 1 ,
   \&.Dv BUFSIZ \&Bc
   .Ed
   .Pp
   See also
   .Sx \&Bq .
   .Ss \&Bq
   Encloses its arguments in square brackets.
   .Pp
   Examples:
   .D1 \&.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
   Closes a
   .Sx \&Bro
   block.  Does not have any tail arguments.
   .Ss \&Bro
   Begins a block enclosed by curly braces.
   Does not have any head arguments.
   .Pp
   Examples:
   .Bd -literal -offset indent
   \&.Bro 1 , ... ,
   \&.Va n \&Brc
   .Ed
   .Pp
   See also
   .Sx \&Brq .
   .Ss \&Brq
   Encloses its arguments in curly braces.
   .Pp
   Examples:
   .D1 \&.Brq 1 , ... , \&Va n
   .Pp
   See also
   .Sx \&Bro .
   .Ss \&Bsx
   Format the BSD/OS version provided as an argument, or a default value if
   no argument is provided.
   .Pp
   Examples:
   .D1 \&.Bsx 1.0
   .D1 \&.Bsx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   .Sx \&Ox ,
   and
   .Sx \&Ux .
   .Ss \&Bt
   Prints
   .Dq is currently in beta test.
   .Ss \&Bx
   Format the BSD version provided as an argument, or a default value if no
   argument is provided.
   .Pp
   Examples:
   .D1 \&.Bx 4.4
   .D1 \&.Bx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   .Sx \&Ox ,
   and
   .Sx \&Ux .
   .Ss \&Cd
   Configuration declaration.
   This denotes strings accepted by
   .Xr config 8 .
   .Pp
   Examples:
   .D1 \&.Cd device le0 at scode?
   .Pp
   .Em Remarks :
   this macro is commonly abused by using quoted literals to retain
   white-space and align consecutive
   .Sx \&Cd
   declarations.
   This practise is discouraged.
   .Ss \&Cm
   Command modifiers.
   Useful when specifying configuration options or keys.
   .Pp
   Examples:
   .D1 \&.Cm ControlPath
   .D1 \&.Cm ControlMaster
   .Pp
   See also
   .Sx \&Fl .
   .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:
   .D1 \&.D1 \&Fl abcdefgh
   .Pp
   See also
   .Sx \&Bd
   and
   .Sx \&Dl .
   .Ss \&Db
   .Ss \&Dc
   Closes a
   .Sx \&Do
   block.  Does not have any tail arguments.
   .Ss \&Dd
   Document date.
   This is the mandatory first macro of any
   .Nm
   manual.
   Its calling syntax is as follows:
   .Pp
   .D1 \. Ns Sx \&Dd Cm date
   .Pp
 The  The
   .Cm date
   field may be either
   .Ar $\&Mdocdate$ ,
   which signifies the current manual revision date dictated by
   .Xr cvs 1 ,
   or instead a valid canonical date as specified by
   .Sx Dates .
   If a date does not conform, the current date is used instead.
   .Pp
   Examples:
   .D1 \&.Dd $\&Mdocdate$
   .D1 \&.Dd $\&Mdocdate: July 21 2007$
   .D1 \&.Dd July 21, 2007
   .Pp
   See also
   .Sx \&Dt
   and
   .Sx \&Os .
   .Ss \&Dl
   One-line intended display.
   This is formatted as literal text and is useful for commands and
   invocations.
   It is followed by a newline.
   .Pp
   Examples:
   .D1 \&.Dl % mandoc mdoc.7 | less
   .Pp
   See also
   .Sx \&Bd
   and
   .Sx \&D1 .
   .Ss \&Do
   Begins a block enclosed by double quotes.  Does not have any head
   arguments.
   .Pp
   Examples:
   .D1 \&.D1 \&Do April is the cruellest month \&Dc \e(em T.S. Eliot
   .Pp
   See also
   .Sx \&Dq .
   .Ss \&Dq
   Encloses its arguments in 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 \&Do .
   .Ss \&Dt
   Document title.
   This is the mandatory second macro of any
 .Nm  .Nm
 utility was written by  file.
 .An Kristaps Dzonsons Aq kristaps@openbsd.org .  Its calling syntax is as follows:
 .\" SECTION  
 .Sh CAVEATS  
 There are several ambiguous parts of mdoc.  
 .Pp  .Pp
   .D1 \. Ns Sx \&Dt Op Cm title Op Cm section Op Cm volume | arch
   .Pp
   Its arguments are as follows:
   .Bl -tag -width Ds -offset Ds
   .It Cm title
   The document's title (name), defaulting to
   .Qq UNKNOWN
   if unspecified.
   It should be capitalised.
   .It Cm section
   The manual section.
   This may be one of
   .Ar 1
   .Pq utilities ,
   .Ar 2
   .Pq system calls ,
   .Ar 3
   .Pq libraries ,
   .Ar 3p
   .Pq Perl libraries ,
   .Ar 4
   .Pq devices ,
   .Ar 5
   .Pq file formats ,
   .Ar 6
   .Pq games ,
   .Ar 7
   .Pq miscellaneous ,
   .Ar 8
   .Pq system utilities ,
   .Ar 9
   .Pq kernel functions ,
   .Ar X11
   .Pq X Window System ,
   .Ar X11R6
   .Pq X Window System ,
   .Ar unass
   .Pq unassociated ,
   .Ar local
   .Pq local system ,
   .Ar draft
   .Pq draft manual ,
   or
   .Ar paper
   .Pq paper .
   It should correspond to the manual's filename suffix and defaults to
   .Qq 1
   if unspecified.
   .It Cm volume
   This overrides the volume inferred from
   .Ar section .
   This field is optional, and if specified, must be one of
   .Ar USD
   .Pq users' supplementary documents ,
   .Ar PS1
   .Pq programmers' supplementary documents ,
   .Ar AMD
   .Pq administrators' supplementary documents ,
   .Ar SMM
   .Pq system managers' manuals ,
   .Ar URM
   .Pq users' reference manuals ,
   .Ar PRM
   .Pq programmers' reference manuals ,
   .Ar KM
   .Pq kernel manuals ,
   .Ar IND
   .Pq master index ,
   .Ar MMI
   .Pq master index ,
   .Ar LOCAL
   .Pq local manuals ,
   .Ar LOC
   .Pq local manuals ,
   or
   .Ar CON
   .Pq contributed manuals .
   .It Cm arch
   This specifies a specific relevant architecture.
   If
   .Cm volume
   is not provided, it may be used in its place, else it may be used
   subsequent that.
   It, too, is optional.
   It must be one of
   .Ar alpha ,
   .Ar amd64 ,
   .Ar amiga ,
   .Ar arc ,
   .Ar arm ,
   .Ar armish ,
   .Ar aviion ,
   .Ar hp300 ,
   .Ar hppa ,
   .Ar hppa64 ,
   .Ar i386 ,
   .Ar landisk ,
   .Ar loongson ,
   .Ar luna88k ,
   .Ar mac68k ,
   .Ar macppc ,
   .Ar mvme68k ,
   .Ar mvme88k ,
   .Ar mvmeppc ,
   .Ar pmax ,
   .Ar sgi ,
   .Ar socppc ,
   .Ar sparc ,
   .Ar sparc64 ,
   .Ar sun3 ,
   .Ar vax ,
   or
   .Ar zaurus .
   .El
   .Pp
   Examples:
   .D1 \&.Dt FOO 1
   .D1 \&.Dt FOO 4 KM
   .D1 \&.Dt FOO 9 i386
   .Pp
   See also
   .Sx \&Dd
   and
   .Sx \&Os .
   .Ss \&Dv
   Defined variables such as preprocessor constants.
   .Pp
   Examples:
   .D1 \&.Dv BUFSIZ
   .D1 \&.Dv STDOUT_FILENO
   .Pp
   See also
   .Sx \&Er .
   .Ss \&Dx
   Format the DragonFly BSD version provided as an argument, or a default
   value if no argument is provided.
   .Pp
   Examples:
   .D1 \&.Dx 2.4.1
   .D1 \&.Dx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   .Sx \&Ox ,
   and
   .Sx \&Ux .
   .Ss \&Ec
   .Ss \&Ed
   .Ss \&Ef
   .Ss \&Ek
   .Ss \&El
   .Ss \&Em
   Denotes text that should be emphasised.
   Note that this is a presentation term and should not be used for
   stylistically decorating technical terms.
   .Pp
   Examples:
   .D1 \&.Em Warnings!
   .D1 \&.Em Remarks :
   .Ss \&En
   .Ss \&Eo
   .Ss \&Er
   Display error constants.
   .Pp
   Examples:
   .D1 \&.Er EPERM
   .D1 \&.Er ENOENT
   .Pp
   See also
   .Sx \&Dv .
   .Ss \&Es
   .Ss \&Ev
   Environmental variables such as those specified in
   .Xr environ 7 .
   .Pp
   Examples:
   .D1 \&.Ev DISPLAY
   .D1 \&.Ev PATH
   .Ss \&Ex
   Inserts text regarding a utility's exit values.
   This macro must have first the
   .Fl std
   argument specified, then an optional
   .Ar utility .
   If
   .Ar utility
   is not provided, the document's name as stipulated in
   .Sx \&Nm
   is provided.
   .Ss \&Fa
   .Ss \&Fc
   .Ss \&Fd
   .Ss \&Fl
   Command-line flag.
   Used when listing arguments to command-line utilities.
   Prints a fixed-width hyphen
   .Sq \-
   directly followed by each argument.
   If no arguments are provided, a hyphen is printed followed by a space.
   If the argument is a macro, a hyphen is prefixed to the subsequent macro
   output.
   .Pp
   Examples:
   .D1 \&.Fl a b c
   .D1 \&.Fl \&Pf a b
   .D1 \&.Fl
   .D1 \&.Op \&Fl o \&Ns \&Ar file
   .Pp
   See also
   .Sx \&Cm .
   .Ss \&Fn
   .Ss \&Fo
   .Ss \&Fr
   .Ss \&Ft
   .Ss \&Fx
   Format the FreeBSD version provided as an argument, or a default value
   if no argument is provided.
   .Pp
   Examples:
   .D1 \&.Fx 7.1
   .D1 \&.Fx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Nx ,
   .Sx \&Ox ,
   and
   .Sx \&Ux .
   .Ss \&Hf
   .Ss \&Ic
   .Ss \&In
   .Ss \&It
   .Ss \&Lb
   Specify a library.
   The calling syntax is as follows:
   .Pp
   .D1 \. Ns Sx \&Lb Cm library
   .Pp
   The
   .Cm library
   parameter may be a system library, such as
   .Cm libz
   or
   .Cm libpam ,
   in which case a small library description is printed next to the linker
   invocation; or a custom library, in which case the library name is
   printed in quotes.
   This is most commonly used in the
   .Em SYNOPSIS
   section as described in
   .Sx MANUAL STRUCTURE .
   .Pp
   Examples:
   .D1 \&.Lb libz
   .D1 \&.Lb mdoc
   .Ss \&Li
   .Ss \&Lk
   Format a hyperlink.
   The calling syntax is as follows:
   .Pp
   .D1 \. Ns Sx \&Lk Cm uri Op Cm name
   .Pp
   Examples:
   .D1 \&.Lk http://bsd.lv "The BSD.lv Project"
   .D1 \&.Lk http://bsd.lv
   .Pp
   See also
   .Sx \&Mt .
   .Ss \&Lp
   .Ss \&Ms
   .Ss \&Mt
   .Ss \&Nd
   .Ss \&Nm
   .Ss \&No
   .Ss \&Ns
   .Ss \&Nx
   Format the NetBSD version provided as an argument, or a default value if
   no argument is provided.
   .Pp
   Examples:
   .D1 \&.Nx 5.01
   .D1 \&.Nx
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Ox ,
   and
   .Sx \&Ux .
   .Ss \&Oc
   .Ss \&Oo
   .Ss \&Op
   .Ss \&Os
   Document operating system version.
   This is the mandatory third macro of
   any
   .Nm
   file.  Its calling syntax is as follows:
   .Pp
   .D1 \. Ns Sx \&Os Op Cm system
   .Pp
   The optional
   .Cm system
   parameter specifies the relevant operating system or environment.
   Left unspecified, it defaults to the local operating system version.
   This is the suggested form.
   .Pp
   Examples:
   .D1 \&.Os
   .D1 \&.Os KTH/CSC/TCS
   .D1 \&.Os BSD 4.3
   .Pp
   See also
   .Sx \&Dd
   and
   .Sx \&Dt .
   .Ss \&Ot
   Unknown usage.
   .Pp
   .Em Remarks :
   this macro has been deprecated.
   .Ss \&Ox
   Format the OpenBSD version provided as an argument, or a default value
   if no argument is provided.
   .Pp
   Examples:
   .D1 \&.Ox 4.5
   .D1 \&.Ox
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ux .
   .Ss \&Pa
   .Ss \&Pc
   .Ss \&Pf
   .Ss \&Po
   .Ss \&Pp
   .Ss \&Pq
   .Ss \&Qc
   .Ss \&Ql
   .Ss \&Qo
   .Ss \&Qq
   .Ss \&Re
   Closes a
   .Sx \&Rs
   block.
   Does not have any tail arguments.
   .Ss \&Rs
   Begins a bibliographic
   .Pq Dq reference
   block.
   Does not have any head arguments.
   The block macro may only contain
   .Sx \&%A ,
   .Sx \&%B ,
   .Sx \&%C ,
   .Sx \&%D ,
   .Sx \&%I ,
   .Sx \&%J ,
   .Sx \&%N ,
   .Sx \&%O ,
   .Sx \&%P ,
   .Sx \&%Q ,
   .Sx \&%R ,
   .Sx \&%T ,
   and
   .Sx \&%V
   child macros (at least one must be specified).
   .Pp
   Examples:
   .Bd -literal -offset indent -compact
   \&.Rs
   \&.%A J. E. Hopcroft
   \&.%A J. D. Ullman
   \&.%B Introduction to Automata Theory, Languages, and Computation
   \&.%I Addison-Wesley
   \&.%C Reading, Massachusettes
   \&.%D 1979
   \&.Re
   .Ed
   .Pp
   If an
   .Sx \&Rs
   block is used within a SEE ALSO section, a vertical space is asserted
   before the rendered output, else the block continues on the current
   line.
   .Ss \&Rv
   .Ss \&Sc
   .Ss \&Sh
   .Ss \&Sm
   .Ss \&So
   .Ss \&Sq
   .Ss \&Ss
   .Ss \&St
   .Ss \&Sx
   .Ss \&Sy
   .Ss \&Tn
   .Ss \&Ud
   Prints out
   .Dq currently under development.
   .Ss \&Ux
   Format the UNIX name.
   Accepts no argument.
   .Pp
   Examples:
   .D1 \&.Ux
   .Pp
   See also
   .Sx \&At ,
   .Sx \&Bsx ,
   .Sx \&Bx ,
   .Sx \&Dx ,
   .Sx \&Fx ,
   .Sx \&Nx ,
   and
   .Sx \&Ox .
   .Ss \&Va
   .Ss \&Vt
   A variable type.
   This is also used for indicating global variables in the SYNOPSIS
   section, in which case a variable name is also specified.
   Note that it accepts
   .Sx Block partial-implicit
   syntax when invoked as the first macro in the SYNOPSIS section, else it
   accepts ordinary
   .Sx In-line
   syntax.
   .Pp
   Note that this should not be confused with
   .Sx \&Ft ,
   which is used for function return types.
   .Pp
   Examples:
   .D1 \&.Vt unsigned char
   .D1 \&.Vt extern const char * const sys_signame[] ;
   .Pp
   See also
   .Sx \&Ft
   and
   .Sx \&Va .
   .Ss \&Xc
   Close a scope opened by
   .Sx \&Xo .
   .Ss \&Xo
   Open an extension scope.
   This macro originally existed to extend the 9-argument limit of troff;
   since this limit has been lifted, the macro has been deprecated.
   .Ss \&Xr
   Link to another manual
   .Pq Qq cross-reference .
   Its calling syntax is
   .Pp
   .D1 \. Ns Sx \&Xr Cm name section
   .Pp
   The
   .Cm name
   and
   .Cm section
   are the name and section of the linked manual.
   If
   .Cm section
   is followed by non-punctuation, an
   .Sx \&Ns
   is inserted into the token stream.
   This behaviour is for compatibility with
   .Xr groff 1 .
   .Pp
   Examples:
   .D1 \&.Xr mandoc 1
   .D1 \&.Xr mandoc 1 ;
   .D1 \&.Xr mandoc 1 \&Ns s behaviour
   .Ss \&br
   .Ss \&sp
   .Sh COMPATIBILITY
   This section documents compatibility between mandoc and other other
   troff implementations, at this time limited to GNU troff
   .Pq Qq groff .
   The term
   .Qq historic groff
   refers to groff versions before the
   .Pa doc.tmac
   file re-write
   .Pq somewhere between 1.15 and 1.19 .
   .Pp
   Heirloom troff, the other significant troff implementation accepting
   \-mdoc, is similar to historic groff.
   .Pp
 .Bl -dash -compact  .Bl -dash -compact
 .\" LIST-ITEM  
 .It  .It
 .Sq \&.Fa  The comment syntax
 should be  .Sq \e."
 .Sq \&.Va  is no longer accepted.
 as function arguments are variables.  
 .\" LIST-ITEM  
 .It  .It
 .Sq \&.Ft  In groff, the
 should be  .Sx \&Pa
 .Sq \&.Vt  macro does not format its arguments when used in the FILES section under
 as function return types are still types.  Furthermore, the  certain list types.
 .Sq \&.Ft  mandoc does.
 should be removed and  
 .Sq \&.Fo ,  
 which ostensibly follows it, should follow the same convention as  
 .Sq \&.Va .  
 .\" LIST-ITEM  
 .It  .It
 .Sq \&.Va  Historic groff does not print a dash for empty
 should formalise that only one or two arguments are acceptable: a  .Sx \&Fl
 variable name and optional, preceeding type.  arguments.
 .\" LIST-ITEM  mandoc and newer groff implementations do.
 .It  .It
 .Sq \&.Fd  groff behaves irregularly when specifying
 is ambiguous.  It's commonly used to indicate an include file in the  .Sq \ef
 synopsis section.  .Sx Text Decoration
 .Sq \&.In  within line-macro scopes.
 should be used, instead.  mandoc follows a consistent system.
 .\" LIST-ITEM  
 .It  .It
 Only the  In mandoc, negative scaling units are truncated to zero; groff would
 .Sq \-literal  move to prior lines.
 argument to  Furthermore, the
 .Sq \&.Bd  .Sq f
 makes sense.  The remaining ones should be removed.  scaling unit, while accepted, is rendered as the default unit.
 .\" LIST-ITEM  
 .It  .It
 The  In quoted literals, groff allowed pair-wise double-quotes to produce a
 .Sq \&.Xo  standalone double-quote in formatted output.
   This idiosyncratic behaviour is not applicable in mandoc.
   .It
   Display types
   .Sx \&Bd
   .Fl center
 and  and
 .Sq \&.Xc  .Fl right
 macros should be deprecated.  are aliases for
 .\" LIST-ITEM  .Fl left
   in manodc.  Furthermore, the
   .Fl file Ar file
   argument is ignored.
   Lastly, since text is not right-justified in mandoc (or even groff),
   .Fl ragged
   and
   .Fl filled
   are aliases, as are
   .Fl literal
   and
   .Fl unfilled .
 .It  .It
 The  Historic groff has many un-callable macros.
 .Sq \&.Dt  Most of these (excluding some block-level macros) are now callable.
 macro lacks clarity.  It should be absolutely clear which title will  
 render when formatting the manual page.  
 .\" LIST-ITEM  
 .It  .It
 A  The vertical bar
 .Sq \&.Lx  .Sq \(ba
 should be provided for Linux (\(`a la  made historic groff
 .Sq \&.Ox ,  .Qq go orbital
 .Sq \&.Nx  but has been a proper delimiter since then.
 etc.).  
 .\" LIST-ITEM  
 .It  .It
 There's no way to refer to references in  .Sx \&It Fl nested
 .Sq \&.Rs/.Re  is assumed for all lists (it wasn't in historic groff): any list may be
 blocks.  nested and
   .Fl enum
   lists will restart the sequence only for the sub-list.
   .It
   Some manuals use
   .Sx \&Li
   incorrectly by following it with a reserved character and expecting the
   delimiter to render.
   This is not supported in mandoc.
   .It
   In groff, the
   .Sx \&Fo
   macro only produces the first parameter.
   This is not the case in mandoc.
   .It
   In groff, the
   .Sx \&Cd ,
   .Sx \&Er ,
   .Sx \&Ex ,
   and
   .Sx \&Rv
   macros were stipulated only to occur in certain manual sections.
   mandoc does not have these restrictions.
   .It
   Newer groff and mandoc print
   .Qq AT&T UNIX
   prior to unknown arguments of
   .Sx \&At ;
   older groff did nothing.
 .El  .El
   .Sh SEE ALSO
   .Xr mandoc 1 ,
   .Xr mandoc_char 7
   .Sh AUTHORS
   The
   .Nm
   reference was written by
   .An Kristaps Dzonsons Aq kristaps@bsd.lv .
   .\"
   .\" XXX: this really isn't the place for these caveats.
   .\" .
   .\" .
   .\" .Sh CAVEATS
   .\" There are many ambiguous parts of mdoc.
   .\" .
   .\" .Pp
   .\" .Bl -dash -compact
   .\" .It
   .\" .Sq \&Fa
   .\" should be
   .\" .Sq \&Va
   .\" as function arguments are variables.
   .\" .It
   .\" .Sq \&Ft
   .\" should be
   .\" .Sq \&Vt
   .\" as function return types are still types.  Furthermore, the
   .\" .Sq \&Ft
   .\" should be removed and
   .\" .Sq \&Fo ,
   .\" which ostensibly follows it, should follow the same convention as
   .\" .Sq \&Va .
   .\" .It
   .\" .Sq \&Va
   .\" should formalise that only one or two arguments are acceptable: a
   .\" variable name and optional, preceding type.
   .\" .It
   .\" .Sq \&Fd
   .\" is ambiguous.  It's commonly used to indicate an include file in the
   .\" synopsis section.
   .\" .Sq \&In
   .\" should be used, instead.
   .\" .It
   .\" Only the
   .\" .Sq \-literal
   .\" argument to
   .\" .Sq \&Bd
   .\" makes sense.  The remaining ones should be removed.
   .\" .It
   .\" The
   .\" .Sq \&Xo
   .\" and
   .\" .Sq \&Xc
   .\" macros should be deprecated.
   .\" .It
   .\" The
   .\" .Sq \&Dt
   .\" macro lacks clarity.  It should be absolutely clear which title will
   .\" render when formatting the manual page.
   .\" .It
   .\" A
   .\" .Sq \&Lx
   .\" should be provided for Linux (\(`a la
   .\" .Sq \&Ox ,
   .\" .Sq \&Nx
   .\" etc.).
   .\" .It
   .\" There's no way to refer to references in
   .\" .Sq \&Rs/Re
   .\" blocks.
   .\" .It
   .\" The \-split and \-nosplit dictates via
   .\" .Sq \&An
   .\" are re-set when entering and leaving the AUTHORS section.
   .\" .El
   .\" .
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