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+++ new/usr/src/man/man5/mdoc.5	Fri Jul 18 08:34:41 2014
@@ -0,0 +1,3211 @@
+.\"
+.\" Permission to use, copy, modify, and distribute this software for any
+.\" purpose with or without fee is hereby granted, provided that the above
+.\" copyright notice and this permission notice appear in all copies.
+.\"
+.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+.\"
+.\"
+.\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
+.\" Copyright (c) 2010, 2011 Ingo Schwarze <schwarze@openbsd.org>
+.\" Copyright 2012 Nexenta Systems, Inc. All rights reserved.
+.\" Copyright 2014 Garrett D'Amore <garrett@dmaore.org>
+.\"
+.Dd Jul 16, 2014
+.Dt MDOC 5
+.Os
+.Sh NAME
+.Nm mdoc
+.Nd semantic markup language for formatting manual pages
+.Sh DESCRIPTION
+The
+.Nm mdoc
+language supports authoring of manual pages for the
+.Xr man 1
+utility by allowing semantic annotations of words, phrases,
+page sections and complete manual pages.
+Such annotations are used by formatting tools to achieve a uniform
+presentation across all manuals written in
+.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
+section describes compatibility with other implementations.
+.Pp
+In an
+.Nm
+document, lines beginning with the control character
+.Sq \&.
+are called
+.Dq macro lines .
+The first word is the macro name.
+It consists of two or three letters.
+Most macro names begin with a capital letter.
+For a list of available macros, see
+.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
+\&.Sh Macro lines change control state.
+Text lines are interpreted within the current state.
+.Ed
+.Pp
+Many aspects of the basic syntax of the
+.Nm
+language are based on the
+.Xr roff 5
+language; see the
+.Em LANGUAGE SYNTAX
+and
+.Em MACRO SYNTAX
+sections in the
+.Xr roff 5
+manual for details, in particular regarding
+comments, escape sequences, whitespace, and quoting.
+However, using
+.Xr roff 5
+requests in
+.Nm
+documents is discouraged;
+.Xr mandoc 1
+supports some of them merely for backward compatibility.
+.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 the
+.Sx \&Dd ,
+.Sx \&Dt ,
+and
+.Sx \&Os
+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
+followed by
+.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
+\&.Dd Jan 1, 1970
+\&.Dt PROGNAME section
+\&.Os
+\&.Sh NAME
+\&.Nm progname
+\&.Nd one line description
+\&.\e\(dq .Sh LIBRARY
+\&.\e\(dq For sections 2, 3, & 9 only.
+\&.Sh SYNOPSIS
+\&.Nm progname
+\&.Op Fl options
+\&.Ar
+\&.Sh DESCRIPTION
+The
+\&.Nm
+utility processes files ...
+\&.\e\(dq .Sh IMPLEMENTATION NOTES
+\&.\e\(dq .Sh RETURN VALUES
+\&.\e\(dq For sections 2, 3, & 9 only.
+\&.\e\(dq .Sh ENVIRONMENT
+\&.\e\(dq For sections 1, 1M, 5, & 6 only.
+\&.\e\(dq .Sh FILES
+\&.\e\(dq .Sh EXIT STATUS
+\&.\e\(dq For sections 1, 1M, & 6 only.
+\&.\e\(dq .Sh EXAMPLES
+\&.\e\(dq .Sh DIAGNOSTICS
+\&.\e\(dq For sections 1, 1M, 5, 6, & 7 only.
+\&.\e\(dq .Sh ERRORS
+\&.\e\(dq For sections 2, 3, & 9 only.
+\&.\e\(dq .Sh ARCHITECTURE
+\&.\e\(dq .Sh CODE SET INDEPENDENCE
+\&.\e\(dq For sections 1, 1M, & 3 only.
+\&.\e\(dq .Sh INTERFACE STABILITY
+\&.\e\(dq .Sh MT-LEVEL
+\&.\e\(dq For sections 2 & 3 only.
+\&.\e\(dq .Sh SEE ALSO
+\&.\e\(dq .Xr foobar 1
+\&.\e\(dq .Sh STANDARDS
+\&.\e\(dq .Sh HISTORY
+\&.\e\(dq .Sh AUTHORS
+\&.\e\(dq .Sh CAVEATS
+\&.\e\(dq .Sh BUGS
+\&.\e\(dq .Sh SECURITY CONSIDERATIONS
+\&.\e\(dq Not used in OpenBSD.
+.Ed
+.Pp
+The sections in an
+.Nm
+document are conventionally ordered as they appear above.
+Sections should be composed as follows:
+.Bl -ohang -offset Ds
+.It Em NAME
+The name(s) and a one line description of the documented material.
+The syntax for this as follows:
+.Bd -literal -offset indent
+\&.Nm name0 ,
+\&.Nm name1 ,
+\&.Nm name2
+\&.Nd a one line description
+.Ed
+.Pp
+Multiple
+.Sq \&Nm
+names should be separated by commas.
+.Pp
+The
+.Sx \&Nm
+macro(s) must precede the
+.Sx \&Nd
+macro.
+.Pp
+See
+.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
+.Pp
+See
+.Sx \&Lb .
+.It Em SYNOPSIS
+Documents the utility invocation syntax, function call syntax, or device
+configuration.
+.Pp
+For the first, utilities (sections 1, 1M, and 6), this is
+generally structured as follows:
+.Bd -literal -offset indent
+\&.Nm bar
+\&.Op Fl v
+\&.Op Fl o Ar file
+\&.Op Ar
+\&.Nm foo
+\&.Op Fl v
+\&.Op Fl o Ar file
+\&.Op Ar
+.Ed
+.Pp
+Commands should be ordered alphabetically.
+.Pp
+For the second, function calls (sections 2, 3, 9):
+.Bd -literal -offset indent
+\&.In header.h
+\&.Vt extern const char *global;
+\&.Ft "char *"
+\&.Fn foo "const char *src"
+\&.Ft "char *"
+\&.Fn bar "const char *src"
+.Ed
+.Pp
+Ordering of
+.Sx \&In ,
+.Sx \&Vt ,
+.Sx \&Fn ,
+and
+.Sx \&Fo
+macros should follow C header-file conventions.
+.Pp
+And for the third, configurations (section 7):
+.Bd -literal -offset indent
+\&.Cd \(dqit* at isa? port 0x2e\(dq
+\&.Cd \(dqit* at isa? port 0x4e\(dq
+.Ed
+.Pp
+Manuals not in these sections generally don't need a
+.Em SYNOPSIS .
+.Pp
+Some macros are displayed differently in the
+.Em SYNOPSIS
+section, particularly
+.Sx \&Nm ,
+.Sx \&Cd ,
+.Sx \&Fd ,
+.Sx \&Fn ,
+.Sx \&Fo ,
+.Sx \&In ,
+.Sx \&Vt ,
+and
+.Sx \&Ft .
+All of these macros are output on their own line.
+If two such dissimilar macros are pairwise invoked (except for
+.Sx \&Ft
+before
+.Sx \&Fo
+or
+.Sx \&Fn ) ,
+they are separated by a vertical space, unless in the case of
+.Sx \&Fo ,
+.Sx \&Fn ,
+and
+.Sx \&Ft ,
+which are always separated by vertical space.
+.Pp
+When text and macros following an
+.Sx \&Nm
+macro starting an input line span multiple output lines,
+all output lines but the first will be indented to align
+with the text immediately following the
+.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
+The
+\&.Nm
+utility does this, that, and the other.
+.Ed
+.Pp
+It usually follows with a breakdown of the options (if documenting a
+command), such as:
+.Bd -literal -offset indent
+The arguments are as follows:
+\&.Bl \-tag \-width Ds
+\&.It Fl v
+Print verbose information.
+\&.El
+.Ed
+.Pp
+Manuals not documenting a command won't include the above fragment.
+.Pp
+Since the
+.Em DESCRIPTION
+section usually contains most of the text of a manual, longer manuals
+often use the
+.Sx \&Ss
+macro to form subsections.
+In very long manuals, the
+.Em DESCRIPTION
+may be split into multiple sections, each started by an
+.Sx \&Sh
+macro followed by a non-standard section name, and each having
+several subsections, like in the present
+.Nm
+manual.
+.It Em IMPLEMENTATION NOTES
+Implementation-specific notes should be kept here.
+This is useful when implementing standard functions that may have side
+effects or notable algorithmic implications.
+.It Em RETURN VALUES
+This section documents the
+return values of functions in sections 2, 3, and 9.
+.Pp
+See
+.Sx \&Rv .
+.It Em ENVIRONMENT
+Lists the environment variables used by the utility,
+and explains the syntax and semantics of their values.
+The
+.Xr environ 5
+manual provides examples of typical content and formatting.
+.Pp
+See
+.Sx \&Ev .
+.It Em FILES
+Documents files used.
+It's helpful to document both the file name and a short description of how
+the file is used (created, modified, etc.).
+.Pp
+See
+.Sx \&Pa .
+.It Em EXIT STATUS
+This section documents the
+command exit status for section 1, 6, and 8 utilities.
+Historically, this information was described in
+.Em DIAGNOSTICS ,
+a practise that is now discouraged.
+.Pp
+See
+.Sx \&Ex .
+.It Em EXAMPLES
+Example usages.
+This often contains snippets of well-formed, well-tested invocations.
+Make sure that examples work properly!
+.It Em DIAGNOSTICS
+Documents error conditions.
+This is most useful in section 4 manuals.
+Historically, this section was used in place of
+.Em EXIT STATUS
+for manuals in sections 1, 6, and 8; however, this practise is
+discouraged.
+.Pp
+See
+.Sx \&Bl
+.Fl diag .
+.It Em ERRORS
+Documents error handling in sections 2, 3, and 9.
+.Pp
+See
+.Sx \&Er .
+.It Em ARCHITECTURE
+This section is usually absent, but will be present when the
+interface is specific to one or more architectures.
+.It Em CODE SET INDEPENDENCE
+Indicates whether the interface operates correctly with various different
+code sets.  True independent code sets will support not only ASCII and
+Extended UNIX Codesets (EUC), but also other multi-byte encodings such as
+UTF-8 and GB2312.
+.Pp
+Generally there will be some limitations that are fairly standard.  See
+.Xr standards 5 for more information about some of these.  Most interfaces
+should support at least UTF-8 in addition to ASCII.
+.It Em INTERFACE STABILITY
+Indicates the level of commitment to the interface. Interfaces can be described
+with in the following ways:
+.Bl -tag -width Ds
+.It Nm Standard
+Indicates that the interface is defined by one or more standards bodies.
+Generally, changes to the interface will be carefully managed to conform
+to the relevant standards.  These interfaces are generally the most suitable
+for use in portable programs.
+.It Nm Committed
+Indicates that the interface is intended to be preserved for the long-haul, and
+will rarely, if ever change, and never without notification (barring
+extraordinary and extenuating circumstances). These interfaces are
+preferred over other interfaces with the exeception of
+.Nm Standard
+interfaces.
+.It Nm Uncommitted
+Indicates that the interface may change.  Generally, changes to these interfaces
+should be infrequent, and some effort will be made to address compatibility
+considerations when changing or removing such interfaces.  However, there is
+no firm commitment to the preservation of the interface.  Most often this
+is applied to interfaces where operational experience with the interface
+is still limited and some need to change may be anticipated.
+.Pp
+Consumers should expect to revalidate any
+.Nm Uncommitted
+interfaces when crossing release boundaries.  Products intended for
+use on many releases or intended to support compatibility with future
+releases should avoid these interfaces.
+.It Nm Volatile
+The interface can change at any time for any reason. Often this relates to
+interfaces that are part of external software components that are still evolving
+rapidly.  Consumers should not expect that the interface (either binary or
+source level) will be unchanged from one release to the next.
+.It Nm Not-an-Interface
+Describes something that is specifically not intended for programmatic
+consumption.  For example, specific human-readable output, or the layout
+of graphical items on a user interface, may be described this way.  Generally
+programmatic alternatives to these will be available, and should be used
+when programmatic consumption is needed.
+.It Nm Private
+This is an internal interface.  Generally these interfaces should only be
+used within the project, and should not be used by other programs or modules.
+The interface can and will change without notice as the project needs, at
+any time.
+.Pp
+Most often, Private interfaces will lack any documentation whatsoever, and
+generally any undocumented interface can be assumed to be Private.
+.It Nm Obsolete
+The interface is not intended for use in new projects or programs, and may
+be removed at a future date.  The
+.Nm Obsolete
+word is a modifier that can
+be applied to other commitment levels. For example an
+.Nm Obsolete Committed
+interface is unlikely to be removed or changed, but nonetheless new use
+is discouraged (perhaps a better newer alternative is present).
+.El
+.It Em MT-LEVEL
+This section describes considerations for the interface when used within
+programs that use multiple threads.  More discussion of these considerations
+is made in the MT-Level section of
+.Xr attributes 5 .
+The interface can be described in the following ways.
+.Bl -tag -width Ds
+.It Nm Safe
+Indicates the interface is safe for use within multiple threads.  There
+may be additional caveats that apply, in which case those will be
+described.  Note that some interfaces have semantics which may affect
+other threads, but these should be an intrinsic part of the interface
+rather than an unexpected side effect.  For example, closing a file in
+one thread will cause that file to be closed in all threads.
+.It Nm Unsafe
+Indicates the interface is unsuitable for concurrent use within multiple
+threads.  A threaded application may still make use of the interface, but
+will be required to provide external synchronization means to ensure that
+only a single thread calls the interface at a time.
+.It Nm MT-Safe
+Indicates that the interface is not only safe for concurrent use, but is
+designed for such use.  For example, a
+.Nm Safe
+interface may make use of a global lock to provide safety, but at reduced
+internal concurrency, whereas an
+.Nm MT-Safe
+interface will be designed to be efficient even when used concurrently.
+.It Nm Async-Signal-Safe
+Indicates that the library is safe for use within a signal handler.  An
+.Nm MT-Safe
+interface can be made
+.Nm Async-Signal-Safe
+by ensuring that it blocks signals when acquiring locks.
+.It Nm Safe with Exections
+As for
+.Nm Safe
+but with specific exceptions noted.
+.It Nm MT-Safe with Exections
+As for
+.Nm MT-Safe
+but with specific exceptions noted.
+.El
+.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
+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: Ar month day , year
+.It Sx \&Dt Ta document title: Ar TITLE SECTION Op Ar volume | 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 \&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: Cm on | off
+.It Sx \&Bk , \&Ek Ta keep block: Fl words
+.It Sx \&br Ta force output line break in text mode (no arguments)
+.It Sx \&sp Ta force vertical space: Op Ar height
+.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 \&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)
+.It Sx \&Tn Ta tradename (>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 \&Ql Ta single-quoted literal text: Ql 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 \&Ux Ta Ux
+.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
+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.
+.Ss \&%D
+Publication date of an
+.Sx \&Rs
+block.
+Recommended formats of arguments are
+.Ar month day , year
+or just
+.Ar year .
+.Ss \&%I
+Publisher or issuer name of an
+.Sx \&Rs
+block.
+.Ss \&%J
+Journal name of an
+.Sx \&Rs
+block.
+.Ss \&%N
+Issue number (usually for journals) of an
+.Sx \&Rs
+block.
+.Ss \&%O
+Optional information of an
+.Sx \&Rs
+block.
+.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
+Close an
+.Sx \&Ao
+block.
+Does not have any tail arguments.
+.Ss \&Ad
+Memory address.
+Do not use this for postal addresses.
+.Pp
+Examples:
+.Dl \&.Ad [0,$]
+.Dl \&.Ad 0x00000000
+.Ss \&An
+Author name.
+Can be used both for the authors of the program, function, or driver
+documented in the manual, or for the authors of the manual itself.
+Requires either the name of an author or one of the following arguments:
+.Pp
+.Bl -tag -width "-nosplitX" -offset indent -compact
+.It Fl split
+Start a new output line before each subsequent invocation of
+.Sx \&An .
+.It Fl nosplit
+The opposite of
+.Fl split .
+.El
+.Pp
+The default is
+.Fl nosplit .
+The effect of selecting either of the
+.Fl split
+modes ends at the beginning of the
+.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
+Examples:
+.Dl \&.An -nosplit
+.Dl \&.An Kristaps Dzonsons \&Aq kristaps@bsd.lv
+.Ss \&Ao
+Begin a block enclosed by angle brackets.
+Does not have any head arguments.
+.Pp
+Examples:
+.Dl \&.Fl -key= \&Ns \&Ao \&Ar val \&Ac
+.Pp
+See also
+.Sx \&Aq .
+.Ss \&Ap
+Inserts an apostrophe without any surrounding whitespace.
+This is generally used as a grammatical device when referring to the verb
+form of a function.
+.Pp
+Examples:
+.Dl \&.Fn execve \&Ap d
+.Ss \&Aq
+Encloses its arguments in angle brackets.
+.Pp
+Examples:
+.Dl \&.Fl -key= \&Ns \&Aq \&Ar val
+.Pp
+.Em Remarks :
+this macro is often abused for rendering URIs, which should instead use
+.Sx \&Lk
+or
+.Sx \&Mt ,
+or to note pre-processor
+.Dq Li #include
+statements, which should use
+.Sx \&In .
+.Pp
+See also
+.Sx \&Ao .
+.Ss \&Ar
+Command arguments.
+If an argument is not provided, the string
+.Dq file ...\&
+is used as a default.
+.Pp
+Examples:
+.Dl ".Fl o Ar file"
+.Dl ".Ar"
+.Dl ".Ar arg1 , arg2 ."
+.Pp
+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
+Formats an AT&T version.
+Accepts one optional argument:
+.Pp
+.Bl -tag -width "v[1-7] | 32vX" -offset indent -compact
+.It Cm v[1-7] | 32v
+A version of
+.At .
+.It Cm III
+.At III .
+.It Cm V[.[1-4]]?
+A version of
+.At V .
+.El
+.Pp
+Note that these arguments do not begin with a hyphen.
+.Pp
+Examples:
+.Dl \&.At
+.Dl \&.At III
+.Dl \&.At V.1
+.Pp
+See also
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Bc
+Close a
+.Sx \&Bo
+block.
+Does not have any tail arguments.
+.Ss \&Bd
+Begin a display block.
+Its syntax is as follows:
+.Bd -ragged -offset indent
+.Pf \. Sx \&Bd
+.Fl Ns Ar type
+.Op Fl offset Ar width
+.Op Fl compact
+.Ed
+.Pp
+Display blocks are used to select a different indentation and
+justification than the one used by the surrounding text.
+They may contain both macro lines and text lines.
+By default, a display block is preceded by a vertical space.
+.Pp
+The
+.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 centre-justify each line.
+Using this display type is not recommended; many
+.Nm
+implementations render it poorly.
+.It Fl filled
+Change the positions of line breaks to fill each line, and left- and
+right-justify the resulting block.
+.It Fl literal
+Produce one output line from each input line,
+and do not justify the block at all.
+Preserve white space as it appears in the input.
+Always use a constant-width font.
+Use this for displaying source code.
+.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
+.Pp
+The
+.Ar type
+must be provided first.
+Additional arguments may follow:
+.Bl -tag -width 13n -offset indent
+.It Fl offset Ar width
+Indent the display by the
+.Ar width ,
+which may be one of the following:
+.Bl -item
+.It
+One of the pre-defined strings
+.Cm indent ,
+the width of a standard indentation (six constant width characters);
+.Cm indent-two ,
+twice
+.Cm indent ;
+.Cm left ,
+which has no effect;
+.Cm right ,
+which justifies to the right margin; or
+.Cm center ,
+which aligns around an imagined centre axis.
+.It
+A macro invocation, which selects a predefined width
+associated with that macro.
+The most popular is the imaginary macro
+.Ar \&Ds ,
+which resolves to
+.Sy 6n .
+.It
+A width using the syntax described in
+.Sx Scaling Widths .
+.It
+An arbitrary string, which indents by the length of this string.
+.El
+.Pp
+When the argument is missing,
+.Fl offset
+is ignored.
+.It Fl compact
+Do not assert vertical space before the display.
+.El
+.Pp
+Examples:
+.Bd -literal -offset indent
+\&.Bd \-literal \-offset indent \-compact
+   Hello       world.
+\&.Ed
+.Ed
+.Pp
+See also
+.Sx \&D1
+and
+.Sx \&Dl .
+.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
+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
+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
+.Sx Scaling Widths
+or use the length of the given string.
+The
+.Fl offset
+is a global indentation for the whole list, affecting both item heads
+and bodies.
+For those list types supporting it, the
+.Fl width
+argument requests an additional indentation of item bodies,
+to be added to the
+.Fl offset .
+Unless the
+.Fl compact
+argument is specified, list entries are separated by vertical space.
+.Pp
+A list must specify one of the following list types:
+.Bl -tag -width 12n -offset indent
+.It Fl bullet
+No item heads can be specified, but a bullet will be printed at the head
+of each item.
+Item bodies start on the same output line as the bullet
+and are indented according to the
+.Fl width
+argument.
+.It Fl column
+A columnated list.
+The
+.Fl width
+argument has no effect; instead, each argument specifies the width
+of one column, using either the
+.Sx Scaling Widths
+syntax or the string length of the argument.
+If the first line of the body of a
+.Fl column
+list is not an
+.Sx \&It
+macro line,
+.Sx \&It
+contexts spanning one input line each are implied until an
+.Sx \&It
+macro line is encountered, at which point items start being interpreted as
+described in the
+.Sx \&It
+documentation.
+.It Fl dash
+Like
+.Fl bullet ,
+except that dashes are used in place of bullets.
+.It Fl diag
+Like
+.Fl inset ,
+except that item heads are not parsed for macro invocations.
+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
+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
+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
+Close a
+.Sx \&Bro
+block.
+Does not have any tail arguments.
+.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
+Encloses its arguments in curly braces.
+.Pp
+Examples:
+.Dl \&.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:
+.Dl \&.Bsx 1.0
+.Dl \&.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:
+.Dl \&.Bx 4.3 Tahoe
+.Dl \&.Bx 4.4
+.Dl \&.Bx
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.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
+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
+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
+Switch debugging mode.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Sx \&Db Cm on | off
+.Pp
+This macro is ignored by
+.Xr mandoc 1 .
+.Ss \&Dc
+Close 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 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
+A few alternative date formats are accepted as well
+and converted to the standard form.
+.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
+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:
+.Dl \&.Dl % mandoc mdoc.5 \e(ba less
+.Pp
+See also
+.Sx \&Bd
+and
+.Sx \&D1 .
+.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
+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
+Document title.
+This is the mandatory second macro of any
+.Nm
+file.
+Its syntax is as follows:
+.Bd -ragged -offset indent
+.Pf \. Sx \&Dt
+.Oo
+.Ar title
+.Oo
+.Ar section
+.Op Ar volume
+.Op Ar arch
+.Oc
+.Oc
+.Ed
+.Pp
+Its arguments are as follows:
+.Bl -tag -width Ds -offset Ds
+.It Ar title
+The document's title (name), defaulting to
+.Dq UNKNOWN
+if unspecified.
+It should be capitalised.
+.It Ar section
+The manual section. It should correspond to the manual's filename suffix
+and defaults to
+.Dq 1
+if unspecified.
+.It Ar volume
+This overrides the volume inferred from
+.Ar section .
+This field is optional.
+.It Ar arch
+This specifies the machine architecture a manual page applies to,
+where relevant.
+.El
+.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 and
+.Sx \&Va
+for variable symbols.
+.Ss \&Dx
+Format the DragonFly BSD 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 ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.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
+End a display context started by
+.Sx \&Bd .
+.Ss \&Ef
+End a font mode context started by
+.Sx \&Bf .
+.Ss \&Ek
+End a keep context started by
+.Sx \&Bk .
+.Ss \&El
+End a list context started by
+.Sx \&Bl .
+.Pp
+See also
+.Sx \&Bl
+and
+.Sx \&It .
+.Ss \&Em
+Denotes text that should be
+.Em emphasised .
+Note that this is a presentation term and should not be used for
+stylistically decorating technical terms.
+Depending on the output device, this is usually represented
+using an italic font or underlined characters.
+.Pp
+Examples:
+.Dl \&.Em Warnings!
+.Dl \&.Em Remarks :
+.Pp
+See also
+.Sx \&Bf ,
+.Sx \&Li ,
+.Sx \&No ,
+and
+.Sx \&Sy .
+.Ss \&En
+This macro is obsolete and not implemented in
+.Xr mandoc 1 .
+.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
+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
+This macro is obsolete and not implemented.
+.Ss \&Ev
+Environmental variables such as those specified in
+.Xr environ 5 .
+.Pp
+Examples:
+.Dl \&.Ev DISPLAY
+.Dl \&.Ev PATH
+.Pp
+See also
+.Sx \&Dv
+for general constants.
+.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
+Function argument.
+Its syntax is as follows:
+.Bd -ragged -offset indent
+.Pf \. Sx \&Fa
+.Op Cm argtype
+.Cm argname
+.Ed
+.Pp
+This may be invoked for names with or without the corresponding type.
+It is also used to specify the field name of a structure.
+Most often, the
+.Sx \&Fa
+macro is used in the
+.Em SYNOPSIS
+within
+.Sx \&Fo
+section when documenting multi-line function prototypes.
+If invoked with multiple arguments, the arguments are separated by a
+comma.
+Furthermore, if the following macro is another
+.Sx \&Fa ,
+the last argument will also have a trailing comma.
+.Pp
+Examples:
+.Dl \&.Fa \(dqconst char *p\(dq
+.Dl \&.Fa \(dqint a\(dq \(dqint b\(dq \(dqint c\(dq
+.Dl \&.Fa foo
+.Pp
+See also
+.Sx \&Fo .
+.Ss \&Fc
+End a function context started by
+.Sx \&Fo .
+.Ss \&Fd
+Historically used to document include files.
+This usage has been deprecated in favour of
+.Sx \&In .
+Do not use this macro.
+.Pp
+See also
+.Sx MANUAL STRUCTURE
+and
+.Sx \&In .
+.Ss \&Fl
+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
+A function name.
+Its syntax is as follows:
+.Bd -ragged -offset indent
+.Pf \. Ns 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
+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 Oo Ar argtype Oc 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
+This macro is obsolete and not implemented in
+.Xr mandoc 1 .
+.Pp
+It was used to show function return values.
+The syntax was:
+.Pp
+.Dl Pf . Sx \&Fr Ar value
+.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
+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 ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.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
+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
+An
+.Dq include
+file.
+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
+.Dq #include ,
+and a blank line is inserted in front if there is a preceding
+function declaration.
+This is most often used in section 2, 3, and 9 manual pages.
+.Pp
+Examples:
+.Dl \&.In sys/types.h
+.Pp
+See also
+.Sx MANUAL STRUCTURE .
+.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 <TAB> Ar cell ...
+.D1 Pf \. Sx \&It Ar cell Op Sx \&Ta 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 tabs or by the special
+.Sx \&Ta
+block macro.
+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
+.Sx \&Ta
+is only recognised as a macro when called by other macros,
+not 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 semicolon whitespace except for the last.
+.Pp
+See also
+.Sx \&Bl .
+.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 mdoc
+.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
+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
+Synonym for
+.Sx \&Pp .
+.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
+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
+.Ss \&Nd
+A one line description of the manual's content.
+This may only be invoked in the
+.Em SYNOPSIS
+section subsequent the
+.Sx \&Nm
+macro.
+.Pp
+Examples:
+.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
+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
+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
+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
+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 ,
+.Sx \&Ox ,
+and
+.Sx \&Ux .
+.Ss \&Oc
+Close multi-line
+.Sx \&Oo
+context.
+.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
+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
+Document operating system version.
+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.
+Left unspecified, it defaults to the local operating system version.
+This is the suggested form.
+.Pp
+Examples:
+.Dl \&.Os
+.Dl \&.Os KTH/CSC/TCS
+.Dl \&.Os BSD 4.3
+.Pp
+See also
+.Sx \&Dd
+and
+.Sx \&Dt .
+.Ss \&Ot
+This macro is obsolete and not implemented in
+.Xr mandoc 1 .
+.Pp
+Historical
+.Xr mdoc 5
+packages described it as
+.Dq "old function type (FORTRAN)" .
+.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 ,
+.Sx \&Nx ,
+and
+.Sx \&Ux .
+.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/man5/mdoc.5
+.Pp
+See also
+.Sx \&Lk .
+.Ss \&Pc
+Close parenthesised context opened by
+.Sx \&Po .
+.Ss \&Pf
+Removes the space between its argument
+.Pq Dq prefix
+and the following macro.
+Its syntax is as follows:
+.Pp
+.D1 .Pf Ar prefix macro arguments ...
+.Pp
+This is equivalent to:
+.Pp
+.D1 .No Ar prefix No \&Ns Ar macro arguments ...
+.Pp
+Examples:
+.Dl ".Pf $ Ar variable_name"
+.Dl ".Pf 0x Ar hex_digits"
+.Pp
+See also
+.Sx \&Ns
+and
+.Sx \&Sm .
+.Ss \&Po
+Multi-line version of
+.Sx \&Pq .
+.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
+Parenthesised enclosure.
+.Pp
+See also
+.Sx \&Po .
+.Ss \&Qc
+Close quoted context opened by
+.Sx \&Qo .
+.Ss \&Ql
+Format a single-quoted literal.
+See also
+.Sx \&Qq
+and
+.Sx \&Sq .
+.Ss \&Qo
+Multi-line version of
+.Sx \&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
+Close an
+.Sx \&Rs
+block.
+Does not have any tail arguments.
+.Ss \&Rs
+Begin 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 ,
+.Sx \&%U ,
+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
+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
+Close single-quoted context opened by
+.Sx \&So .
+.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
+Switches the spacing mode for output generated from macros.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Sx \&Sm Cm on | off
+.Pp
+By default, spacing is
+.Cm on .
+When switched
+.Cm off ,
+no white space is inserted between macro arguments and between the
+output generated from adjacent macros, but text lines
+still get normal spacing between words and sentences.
+.Ss \&So
+Multi-line version of
+.Sx \&Sq .
+.Ss \&Sq
+Encloses its arguments in
+.Sq typewriter
+single-quotes.
+.Pp
+See also
+.Sx \&Dq ,
+.Sx \&Qq ,
+and
+.Sx \&So .
+.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
+Replace an abbreviation for a standard with the full form.
+The following standards are recognised:
+.Pp
+.Bl -tag -width "-p1003.1g-2000X" -compact
+.It \-p1003.1-88
+.St -p1003.1-88
+.It \-p1003.1-90
+.St -p1003.1-90
+.It \-p1003.1-96
+.St -p1003.1-96
+.It \-p1003.1-2001
+.St -p1003.1-2001
+.It \-p1003.1-2004
+.St -p1003.1-2004
+.It \-p1003.1-2008
+.St -p1003.1-2008
+.It \-p1003.1
+.St -p1003.1
+.It \-p1003.1b
+.St -p1003.1b
+.It \-p1003.1b-93
+.St -p1003.1b-93
+.It \-p1003.1c-95
+.St -p1003.1c-95
+.It \-p1003.1g-2000
+.St -p1003.1g-2000
+.It \-p1003.1i-95
+.St -p1003.1i-95
+.It \-p1003.2-92
+.St -p1003.2-92
+.It \-p1003.2a-92
+.St -p1003.2a-92
+.It \-p1387.2-95
+.St -p1387.2-95
+.It \-p1003.2
+.St -p1003.2
+.It \-p1387.2
+.St -p1387.2
+.It \-isoC
+.St -isoC
+.It \-isoC-90
+.St -isoC-90
+.It \-isoC-amd1
+.St -isoC-amd1
+.It \-isoC-tcor1
+.St -isoC-tcor1
+.It \-isoC-tcor2
+.St -isoC-tcor2
+.It \-isoC-99
+.St -isoC-99
+.It \-isoC-2011
+.St -isoC-2011
+.It \-iso9945-1-90
+.St -iso9945-1-90
+.It \-iso9945-1-96
+.St -iso9945-1-96
+.It \-iso9945-2-93
+.St -iso9945-2-93
+.It \-ansiC
+.St -ansiC
+.It \-ansiC-89
+.St -ansiC-89
+.It \-ansiC-99
+.St -ansiC-99
+.It \-ieee754
+.St -ieee754
+.It \-iso8802-3
+.St -iso8802-3
+.It \-iso8601
+.St -iso8601
+.It \-ieee1275-94
+.St -ieee1275-94
+.It \-xpg3
+.St -xpg3
+.It \-xpg4
+.St -xpg4
+.It \-xpg4.2
+.St -xpg4.2
+.It \-xpg4.3
+.St -xpg4.3
+.It \-xbd5
+.St -xbd5
+.It \-xcu5
+.St -xcu5
+.It \-xsh5
+.St -xsh5
+.It \-xns5
+.St -xns5
+.It \-xns5.2
+.St -xns5.2
+.It \-xns5.2d2.0
+.St -xns5.2d2.0
+.It \-xcurses4.2
+.St -xcurses4.2
+.It \-susv2
+.St -susv2
+.It \-susv3
+.St -susv3
+.It \-svid4
+.St -svid4
+.El
+.Ss \&Sx
+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
+Format enclosed arguments in symbolic
+.Pq Dq boldface .
+Note that this is a presentation term and should not be used for
+stylistically decorating technical terms.
+.Pp
+See also
+.Sx \&Bf ,
+.Sx \&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
+Format a tradename.
+.Pp
+Since this macro is often implemented to use a small caps font,
+it has historically been used for acronyms (like ASCII) as well.
+Such usage is not recommended because it would use the same macro
+sometimes for semantical annotation, sometimes for physical formatting.
+.Pp
+Examples:
+.Dl \&.Tn IBM
+.Ss \&Ud
+Prints out
+.Dq currently under development.
+.Ss \&Ux
+Format the UNIX name.
+Accepts no argument.
+.Pp
+Examples:
+.Dl \&.Ux
+.Pp
+See also
+.Sx \&At ,
+.Sx \&Bsx ,
+.Sx \&Bx ,
+.Sx \&Dx ,
+.Sx \&Fx ,
+.Sx \&Nx ,
+and
+.Sx \&Ox .
+.Ss \&Va
+A variable name.
+.Pp
+Examples:
+.Dl \&.Va foo
+.Dl \&.Va const char *bar ;
+.Ss \&Vt
+A variable type.
+This is also used for indicating global variables in the
+.Em SYNOPSIS
+section, in which case a variable name is also specified.
+Note that it accepts
+.Sx Block partial-implicit
+syntax when invoked as the first macro 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
+Note that this should not be confused with
+.Sx \&Ft ,
+which is used for function return types.
+.Pp
+Examples:
+.Dl \&.Vt unsigned char
+.Dl \&.Vt extern const char * const sys_signame[] \&;
+.Pp
+See also
+.Sx MANUAL STRUCTURE
+and
+.Sx \&Va .
+.Ss \&Xc
+Close a scope opened by
+.Sx \&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 5 .
+.Ss \&Xr
+Link to another manual
+.Pq Qq cross-reference .
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Sx \&Xr Ar name section
+.Pp
+The
+.Ar name
+and
+.Ar section
+are the name and section of the linked manual.
+If
+.Ar section
+is followed by non-punctuation, an
+.Sx \&Ns
+is inserted into the token stream.
+This behaviour is for compatibility with
+GNU troff.
+.Pp
+Examples:
+.Dl \&.Xr mandoc 1
+.Dl \&.Xr mandoc 1 \&;
+.Dl \&.Xr mandoc 1 \&Ns s behaviour
+.Ss \&br
+Emits a line-break.
+This macro should not be used; it is implemented for compatibility with
+historical manuals.
+.Pp
+Consider using
+.Sx \&Pp
+in the event of natural paragraph breaks.
+.Ss \&sp
+Emits vertical space.
+This macro should not be used; it is implemented for compatibility with
+historical manuals.
+Its syntax is as follows:
+.Pp
+.D1 Pf \. Sx \&sp Op Ar height
+.Pp
+The
+.Ar height
+argument must be formatted as described in
+.Sx Scaling Widths .
+If unspecified,
+.Sx \&sp
+asserts a single vertical space.
+.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 \&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 \&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    >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    \&No     Ta    \&No     Ta    n
+.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    \&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
+.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.
+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:
+.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 5
+font mode, it will automatically restore the previous font when exiting
+its scope.
+Manually switching the font using the
+.Xr roff 5
+.Ql \ef
+font escape sequences is never required.
+.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 1.17,
+which featured a significant update of the
+.Pa doc.tmac
+file.
+.Pp
+Heirloom troff, the other significant troff implementation accepting
+\-mdoc, is similar to historic groff.
+.Pp
+The following problematic behaviour is found in groff:
+.ds hist (Historic groff only.)
+.Pp
+.Bl -dash -compact
+.It
+Display macros
+.Po
+.Sx \&Bd ,
+.Sx \&Dl ,
+and
+.Sx \&D1
+.Pc
+may not be nested.
+\*[hist]
+.It
+.Sx \&At
+with unknown arguments produces no output at all.
+\*[hist]
+Newer groff and mandoc print
+.Qq AT&T UNIX
+and the arguments.
+.It
+.Sx \&Bl Fl column
+does not recognise trailing punctuation characters when they immediately
+precede tabulator characters, but treats them as normal text and
+outputs a space before them.
+.It
+.Sx \&Bd Fl ragged compact
+does not start a new line.
+\*[hist]
+.It
+.Sx \&Dd
+with non-standard arguments behaves very strangely.
+When there are three arguments, they are printed verbatim.
+Any other number of arguments is replaced by the current date,
+but without any arguments the string
+.Dq Epoch
+is printed.
+.It
+.Sx \&Fl
+does not print a dash for an empty argument.
+\*[hist]
+.It
+.Sx \&Fn
+does not start a new line unless invoked as the line macro in the
+.Em SYNOPSIS
+section.
+\*[hist]
+.It
+.Sx \&Fo
+with
+.Pf non- Sx \&Fa
+children causes inconsistent spacing between arguments.
+In mandoc, a single space is always inserted between arguments.
+.It
+.Sx \&Ft
+in the
+.Em SYNOPSIS
+causes inconsistent vertical spacing, depending on whether a prior
+.Sx \&Fn
+has been invoked.
+See
+.Sx \&Ft
+and
+.Sx \&Fn
+for the normalised behaviour in mandoc.
+.It
+.Sx \&In
+ignores additional arguments and is not treated specially in the
+.Em SYNOPSIS .
+\*[hist]
+.It
+.Sx \&It
+sometimes requires a
+.Fl nested
+flag.
+\*[hist]
+In new groff and mandoc, any list may be nested by default and
+.Fl enum
+lists will restart the sequence only for the sub-list.
+.It
+.Sx \&Li
+followed by a delimiter is incorrectly used in some manuals
+instead of properly quoting that character, which sometimes works with
+historic groff.
+.It
+.Sx \&Lk
+only accepts a single link-name argument; the remainder is misformatted.
+.It
+.Sx \&Pa
+does not format its arguments when used in the FILES section under
+certain list types.
+.It
+.Sx \&Ta
+can only be called by other macros, but not at the beginning of a line.
+.It
+.Sx \&%C
+is not implemented.
+.It
+Historic groff only allows up to eight or nine arguments per macro input
+line, depending on the exact situation.
+Providing more arguments causes garbled output.
+The number of arguments on one input line is not limited with mandoc.
+.It
+Historic groff has many un-callable macros.
+Most of these (excluding some block-level macros) are callable
+in new groff and mandoc.
+.It
+.Sq \(ba
+(vertical bar) is not fully supported as a delimiter.
+\*[hist]
+.It
+.Sq \ef
+.Pq font face
+and
+.Sq \ef
+.Pq font family face
+.Sx Text Decoration
+escapes behave irregularly when specified within line-macro scopes.
+.It
+Negative scaling units return to prior lines.
+Instead, mandoc truncates them to zero.
+.El
+.Pp
+The following features are unimplemented in mandoc:
+.Pp
+.Bl -dash -compact
+.It
+.Sx \&Bd
+.Fl file Ar file .
+.It
+.Sx \&Bd
+.Fl offset Ar center
+and
+.Fl offset Ar right .
+Groff does not implement centred and flush-right rendering either,
+but produces large indentations.
+.It
+The
+.Sq \eh
+.Pq horizontal position ,
+.Sq \ev
+.Pq vertical position ,
+.Sq \em
+.Pq text colour ,
+.Sq \eM
+.Pq text filling colour ,
+.Sq \ez
+.Pq zero-length character ,
+.Sq \ew
+.Pq string length ,
+.Sq \ek
+.Pq horizontal position marker ,
+.Sq \eo
+.Pq text overstrike ,
+and
+.Sq \es
+.Pq text size
+escape sequences are all discarded in mandoc.
+.It
+The
+.Sq \ef
+scaling unit is accepted by mandoc, but rendered as the default unit.
+.It
+In quoted literals, groff allows pairwise double-quotes to produce a
+standalone double-quote in formatted output.
+This is not supported by mandoc.
+.El
+.Sh SEE ALSO
+.Xr man 1 ,
+.Xr mandoc 1 ,
+.Xr eqn 5 ,
+.Xr man 5 ,
+.Xr mandoc_char 5 ,
+.Xr roff 5 ,
+.Xr tbl 5
+.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 .
+in July, 2014.
+.Sh AUTHORS
+The
+.Nm
+reference was written by
+.An Kristaps Dzonsons ,
+.Mt kristaps@bsd.lv .
