Provided by: mandoc_1.14.6-3_amd64 bug

NAME

     mdoc — semantic markup language for formatting manual pages

DESCRIPTION

     The mdoc language supports authoring of manual pages for the 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 mdoc, and to support hyperlinking if supported by the output medium.

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

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

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

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

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

MANUAL STRUCTURE

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

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

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

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

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

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

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

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

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

           Multiple ‘Nm’ names should be separated by commas.

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

           See Nm and Nd.

           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:

                 .Lb libarm

           See Lb.

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

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

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

           Commands should be ordered alphabetically.

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

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

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

           And for the third, configurations (section 4):

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

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

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

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

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

                 The
                 .Nm
                 utility does this, that, and the other.

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

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

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

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

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

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

           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.

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

           See Rv.

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

           See Ev.

           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.).

           See Pa.

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

           See Ex.

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

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

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

           See Bl -diag.

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

           See Er.

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

           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.

           See Rs and Xr.

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

           See St.

           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.

           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.

           See An.

           CAVEATS
           Common misuses and misunderstandings should be explained in this section.

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

           SECURITY CONSIDERATIONS
           Documents any security precautions that operators should consider.

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 MACRO REFERENCE.

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

   Sections and cross references
     Sh               section header (one line)
     Ss               subsection header (one line)
     Sx               internal cross reference to a section or subsection
     Xr               cross reference to another manual page: name section
     Tg               tag the definition of a term (<= 1 arguments)
     Pp               start a text paragraph (no arguments)

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

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

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

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

   Various semantic markup
     An               author name (>0 arguments)
     Lk               hyperlink: uri [display_name]
     Mt               “mailto” hyperlink: localpart@domain
     Cd               kernel configuration declaration (>0 arguments)
     Ad               memory address (>0 arguments)
     Ms               mathematical symbol (>0 arguments)

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

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

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

MACRO REFERENCE

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

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

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

     %C location
          Publication city or location of an Rs block.

     %D [month day,] year
          Publication date of an Rs block.  Provide the full English name of the month and all
          four digits of the year.

     %I name
          Publisher or issuer name of an Rs block.

     %J name
          Journal name of an Rs block.

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

     %O line
          Optional information of an Rs block.

     %P number
          Book or journal page number of an Rs block.  Conventionally, the argument starts with
          ‘p.’ for a single page or ‘pp.’ for a range of pages, for example:

                .%P pp. 42\(en47

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

     %R name
          Technical report name of an Rs block.

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

     %U protocol://path
          URI of reference document.

     %V number
          Volume number of an Rs block.

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

     Ad address
          Memory address.  Do not use this for postal addresses.

          Examples:
                .Ad [0,$]
                .Ad 0x00000000

     An -split | -nosplit | first_name ... last_name
          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:

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

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

          Examples:
                .An -nosplit
                .An Kristaps Dzonsons Aq Mt kristaps@bsd.lv

     Ao block
          Begin a block enclosed by angle brackets.  Does not have any head arguments.  This
          macro is almost never useful.  See Aq for more details.

     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.

          Examples:
                .Fn execve Ap d

     Aq line
          Enclose the rest of the input line in angle brackets.  The only important use case is
          for email addresses.  See Mt for an example.

          Occasionally, it is used for names of characters and keys, for example:

                Press the
                .Aq escape
                key to ...

          For URIs, use Lk instead, and In for “#include” directives.  Never wrap Ar in Aq.

          Since Aq usually renders with non-ASCII characters in non-ASCII output modes, do not
          use it where the ASCII characters ‘<’ and ‘>’ are required as syntax elements.
          Instead, use these characters directly in such cases, combining them with the macros
          Pf, Ns, or Eo as needed.

          See also Ao.

     Ar [placeholder ...]
          Command arguments.  If an argument is not provided, the string “file ...” is used as a
          default.

          Examples:
                .Fl o Ar file
                .Ar
                .Ar arg1 , arg2 .

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

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

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

          Note that these arguments do not begin with a hyphen.

          Examples:
                .At
                .At III
                .At V.1

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

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

     Bd -type [-offset width] [-compact]
          Begin a display block.  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.

          The type must be one of the following:

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

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

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

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

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

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

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

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

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

                               A scaling width as described in roff(7).

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

                               When the argument is missing, -offset is ignored.

                -compact       Do not assert vertical space before the display.

          Examples:

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

          See also D1 and Dl.

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

          See also Li, Ef, Em, and Sy.

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

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

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

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

     Bl -type [-width val] [-offset val] [-compact] [col ...]
          Begin a list.  Lists consist of items specified using the It macro, containing a head
          or a body or both.

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

          A list must specify one of the following list types:

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

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

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

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

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

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

                -hyphen       Synonym for -dash.

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

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

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

                -tag          Item bodies are indented according to the -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.

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

          See also El and It.

     Bo block
          Begin a block enclosed by square brackets.  Does not have any head arguments.

          Examples:
                .Bo 1 ,
                .Dv BUFSIZ Bc

          See also Bq.

     Bq line
          Encloses its arguments in square brackets.

          Examples:
                .Bq 1, Dv BUFSIZ

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

          See also Bo.

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

     Bro block
          Begin a block enclosed by curly braces.  Does not have any head arguments.

          Examples:
                .Bro 1 , ... ,
                .Va n Brc

          See also Brq.

     Brq line
          Encloses its arguments in curly braces.

          Examples:
                .Brq 1, ..., Va n

          See also Bro.

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

          Examples:
                .Bsx 1.0
                .Bsx

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

     Bt   Supported only for compatibility, do not use this in new manuals.  Prints “is currently
          in beta test.”

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

          Examples:
                .Bx 4.3 Tahoe
                .Bx 4.4
                .Bx

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

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

          Examples:
                .Cd device le0 at scode?

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

     Cm keyword ...
          Command modifiers.  Typically used for fixed strings passed as arguments to interactive
          commands, to commands in interpreted scripts, or to configuration file directives,
          unless Fl is more appropriate.

          Examples:
                .Nm mt Fl f Ar device Cm rewind
                .Nm ps Fl o Cm pid , Ns Cm command
                .Nm dd Cm if= Ns Ar file1 Cm of= Ns Ar file2
                .Ic set Fl o Cm vi
                .Ic lookup Cm file bind
                .Ic permit Ar identity Op Cm as Ar target

     D1 line
          One-line indented display.  This is formatted by the default rules and is useful for
          simple indented statements.  It is followed by a newline.

          Examples:
                .D1 Fl abcdefgh

          See also Bd and Dl.

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

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

     Dd $Mdocdate$ | month day, year
          Document date for display in the page footer, by convention the date of the last
          change.  This is the mandatory first macro of any mdoc manual.

          The month is the full English month name, the day is an integer number, and the year is
          the full four-digit year.

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

          Examples:
                .Dd $Mdocdate$
                .Dd $Mdocdate: July 2 2018$
                .Dd July 2, 2018

          See also Dt and Os.

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

          Examples:
                .Dl % mandoc mdoc.7 \(ba less

          See also Ql, Bd -literal, and D1.

     Do block
          Begin a block enclosed by double quotes.  Does not have any head arguments.

          Examples:
                .Do
                April is the cruellest month
                .Dc
                \(em T.S. Eliot

          See also Dq.

     Dq line
          Encloses its arguments in “typographic” double-quotes.

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

          See also Qq, Sq, and Do.

     Dt TITLE section [arch]
          Document title for display in the page header.  This is the mandatory second macro of
          any mdoc file.

          Its arguments are as follows:

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

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

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

          Examples:
                .Dt FOO 1
                .Dt FOO 9 i386

          See also Dd and Os.

     Dv identifier ...
          Defined variables such as preprocessor constants, constant symbols, enumeration values,
          and so on.

          Examples:
                .Dv NULL
                .Dv BUFSIZ
                .Dv STDOUT_FILENO

          See also Er and Ev for special-purpose constants, Va for variable symbols, and Fd for
          listing preprocessor variable definitions in the SYNOPSIS.

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

          Examples:
                .Dx 2.4.1
                .Dx

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

     Ec [closing_delimiter]
          Close a scope started by Eo.

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

     Ed   End a display context started by Bd.

     Ef   End a font mode context started by Bf.

     Ek   End a keep context started by Bk.

     El   End a list context started by Bl.  See also It.

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

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

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

          See also No, Ql, and Sy.

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

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

     Eo [opening_delimiter]
          An arbitrary enclosure.  The opening_delimiter argument is used as the enclosure head,
          for example, specifying \(lq will emulate Do.

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

          Examples:
                .Er EPERM
                .Er ENOENT

          See also Dv for general constants.

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

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

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

          Examples:
                .Ev DISPLAY
                .Ev PATH

          See also Dv for general constants.

     Ex -std [utility ...]
          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.

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

          See also Rv.

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

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

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

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

          See also Fo.

     Fc   End a function context started by Fo.

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

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

          See also MANUAL STRUCTURE, In, and Dv.

     Fl [word ...]
          Command-line flag or option.  Used when listing arguments to command-line utilities.
          For each argument, prints an ASCII hyphen-minus character ‘-’, immediately followed by
          the argument.  If no arguments are provided, a hyphen-minus is printed followed by a
          space.  If the argument is a macro, a hyphen-minus is prefixed to the subsequent macro
          output.

          Examples:
                .Nm du Op Fl H | L | P
                .Nm ls Op Fl 1AaCcdFfgHhikLlmnopqRrSsTtux
                .Nm route Cm add Fl inet Ar destination gateway
                .Nm locate.updatedb Op Fl \-fcodes Ns = Ns Ar dbfile
                .Nm aucat Fl o Fl
                .Nm kill Fl Ar signal_number

          For GNU-sytle long options, escaping the additional hyphen-minus is not strictly
          required, but may be safer with future versions of GNU troff; see mandoc_char(7) for
          details.

          See also Cm.

     Fn funcname [argument ...]
          A function name.

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

          Examples:
                .Fn "int funcname" "int arg0" "int arg1"
                .Fn funcname "int arg0"
                .Fn funcname arg0

                .Ft functype
                .Fn funcname

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

     Fo funcname
          Begin a function block.  This is a multi-line version of Fn.

          Invocations usually occur in the following context:

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

          A Fo scope is closed by Fc.

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

     Fr number
          This macro is obsolete.  No replacement markup is needed.

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

     Ft functype
          A function type.

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

          Examples:
                .Ft int
                .Ft functype
                .Fn funcname

          See also MANUAL STRUCTURE, Fn, and Fo.

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

          Examples:
                .Fx 7.1
                .Fx

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

     Hf filename
          This macro is not implemented in mandoc(1).  It was used to include the contents of a
          (header) file literally.

     Ic keyword ...
          Internal or interactive command, or configuration instruction in a configuration file.
          See also Cm.

          Examples:
                .Ic :wq
                .Ic hash
                .Ic alias

          Note that using Ql, Dl, or Bd -literal is preferred for displaying code samples; the Ic
          macro is used when referring to an individual command name.

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

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

          Examples:
                .In sys/types.h

          See also MANUAL STRUCTURE.

     It [head]
          A list item.  The syntax of this macro depends on the list type.

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

                .It args

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

                .It

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

          The -tag list has the following syntax:

                .It [args]

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

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

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

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

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

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

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

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

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

          See also Bl.

     Lb libname
          Specify a library.

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

          Examples:
                .Lb libz
                .Lb libmandoc

     Li word ...
          Request a typewriter (literal) font.  Deprecated because on terminal output devices,
          this is usually indistinguishable from normal text.  For literal displays, use Ql
          (in-line), Dl (single line), or Bd -literal (multi-line) instead.

     Lk uri [display_name]
          Format a hyperlink.

          Examples:
                .Lk https://bsd.lv "The BSD.lv Project"
                .Lk https://bsd.lv

          See also Mt.

     Lp   Deprecated synonym for Pp.

     Ms name
          Display a mathematical symbol.

          Examples:
                .Ms sigma
                .Ms aleph

     Mt localpart@domain
          Format a “mailto:” hyperlink.

          Examples:
                .Mt discuss@manpages.bsd.lv
                .An Kristaps Dzonsons Aq Mt kristaps@bsd.lv

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

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

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

          See also Nm.

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

          Examples:

                .Sh SYNOPSIS
                .Nm cat
                .Op Fl benstuv
                .Op Ar

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

     No word ...
          Normal text.  Closes the scope of any preceding in-line macro.  When used after
          physical formatting macros like Em or Sy, switches back to the standard font face and
          weight.  Can also be used to embed plain text strings in macro lines using semantic
          annotation macros.

          Examples:
                .Em italic , Sy bold , No and roman

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

          See also Em, Ql, and Sy.

     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 No
          macro.

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

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

          See also No and Sm.

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

          Examples:
                .Nx 5.01
                .Nx

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

     Oc   Close multi-line Oo context.

     Oo block
          Multi-line version of Op.

          Examples:
                .Oo
                .Op Fl flag Ns Ar value
                .Oc

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

          Examples:
                .Op Fl a Ar b
                .Op Ar a | b

          See also Oo.

     Os [system [version]]
          Operating system version for display in the page footer.  This is the mandatory third
          macro of any mdoc file.

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

          Examples:
                .Os
                .Os KTH/CSC/TCS
                .Os BSD 4.3

          See also Dd and Dt.

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

          Historical mdoc packages described it as “old function type (FORTRAN)”.

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

          Examples:
                .Ox 4.5
                .Ox

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

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

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

          See also Lk.

     Pc   Close parenthesised context opened by Po.

     Pf prefix macro [argument ...]
          Removes the space between its argument and the following macro.  It is equivalent to:

                No \&prefix Ns macro [argument ...]

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

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

          See also Ns and Sm.

     Po block
          Multi-line version of Pq.

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

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

     Pq line
          Parenthesised enclosure.

          See also Po.

     Qc   Close quoted context opened by Qo.

     Ql line
          In-line literal display.  This can be used for complete command invocations and for
          multi-word code examples when an indented display is not desired.

          See also Dl and Bd -literal.

     Qo block
          Multi-line version of Qq.

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

          See also Dq, Sq, and Qo.

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

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

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

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

     Rv -std [function ...]
          Insert a standard sentence regarding a function call's return value of 0 on success and
          -1 on error, with the errno libc global variable set on error.

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

          See also Ex.

     Sc   Close single-quoted context opened by So.

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

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

          See also Pp, Ss, and Sx.

     Sm [on | off]
          Switches the spacing mode for output generated from macros.

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

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

     So block
          Multi-line version of Sq.

     Sq line
          Encloses its arguments in ‘typewriter’ single-quotes.

          See also Dq, Qq, and So.

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

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

          See also Pp, Sh, and Sx.

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

          C language standards

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

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

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

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

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

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

          POSIX.1 before the Single UNIX Specification

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

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

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

             -p1003.1c-95    IEEE Std 1003.1c-1995 (“POSIX.1”)
                             POSIX thread interfaces.

             -p1003.1i-95    IEEE Std 1003.1i-1995 (“POSIX.1”)
                             Technical Corrigendum.

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

          X/Open Portability Guide version 4 and related standards

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

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

             -p1003.2a-92    IEEE Std 1003.2a-1992 (“POSIX.2”)
                             Updates to POSIX.2.

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

          Single UNIX Specification version 1 and related standards

             -susv1
             -xpg4.2         X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”)
                             This standard was published in 1994.  It was used as the basis for
                             UNIX 95 certification.  The following three refer to parts of it.

             -xsh4.2

             -xcurses4.2     X/Open Curses Issue 4, Version 2 (“XCURSES4.2”)

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

             -svid4          System V Interface Definition, Fourth Edition (“SVID4”),
                             Published in 1995.

          Single UNIX Specification version 2 and related standards

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

             -xbd5           X/Open Base Definitions Issue 5 (“XBD5”)

             -xsh5           X/Open System Interfaces and Headers Issue 5 (“XSH5”)

             -xcu5           X/Open Commands and Utilities Issue 5 (“XCU5”)

             -xns5           X/Open Networking Services Issue 5 (“XNS5”)
             -xns5.2         X/Open Networking Services Issue 5.2 (“XNS5.2”)

          Single UNIX Specification version 3

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

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

          Single UNIX Specification version 4

             -p1003.1-2008   IEEE Std 1003.1-2008 (“POSIX.1”)
             -susv4
                             This standard is also called X/Open Portability Guide version 7.

          Other standards

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

             -iso8601        ISO 8601
                             Representation of dates and times, published in 1988.

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

             -ieee1275-94    IEEE Std 1275-1994 (“Open Firmware”)

     Sx Title line
          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.

          Examples:
                .Sx MANUAL STRUCTURE

          See also Sh and Ss.

     Sy word ...
          Request a boldface font.

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

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

          See also Em, No, and Ql.

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

     Tg [term]
          Announce that the next input line starts a definition of the term.  This macro must
          appear alone on its own input line.  The argument defaults to the first argument of the
          first macro on the next line.  The argument may not contain whitespace characters, not
          even when it is quoted.  This macro is a mandoc(1) extension and is typically ignored
          by other formatters.

          When viewing terminal output with less(1), the interactive :t command can be used to go
          to the definition of the term as described for the MANPAGER variable in man(1); when
          producing HTML output, a fragment identifier (id attribute) is generated, to be used
          for deep linking to this place of the document.

          In most cases, adding a Tg macro would be redundant because mandoc(1) is able to
          automatically tag most definitions.  This macro is intended for cases where automatic
          tagging of a term is unsatisfactory, for example if a definition is not tagged
          automatically (false negative) or if places are tagged that do not define the term
          (false positives).  When there is at least one Tg macro for a term, no other places are
          automatically marked as definitions of that term.

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

     Ud   Supported only for compatibility, do not use this in new manuals.  Prints out
          “currently under development.”

     Ux   Supported only for compatibility, do not use this in new manuals.  Prints out “UNIX”.

     Va [type] identifier ...
          A variable name.

          Examples:
                .Va foo
                .Va const char *bar;

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

     Vt type [identifier]
          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 Block partial-implicit
          syntax when invoked as the first macro on an input line in the SYNOPSIS section, else
          it accepts ordinary In-line syntax.  In the former case, this macro starts a new output
          line, and a blank line is inserted in front if there is a preceding function definition
          or include directive.

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

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

     Xc   Close a scope opened by Xo.

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

     Xr name section
          Link to another manual ("cross-reference").

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

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

MACRO SYNTAX

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

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

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

     The Scope column, if applicable, describes closure rules.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   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 (n), then the
     macro accepts an arbitrary number of arguments.

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

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

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

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

   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 (‘\&’).  In text lines, delimiters never need escaping, but may be used as normal
     punctuation.

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

           .Aq ( [ word ] ) .

     renders as:

           ([⟨word⟩]).

     Opening delimiters are:

           (       left parenthesis
           [       left bracket

     Closing delimiters are:

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

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

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

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

     renders as:

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

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

           |       vertical bar

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

     Appending a zero-width space (‘\&’) to the end of an input line is also useful to prevent
     the interpretation of a trailing period, exclamation or question mark as the end of a
     sentence, for example when an abbreviation happens to occur at the end of a text or macro
     input line.

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

COMPATIBILITY

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

     The following problematic behaviour is found in groff:

     -   Pa does not format its arguments when used in the FILES section under certain list
         types.
     -   Ta can only be called by other macros, but not at the beginning of a line.
     -   ‘\f’ (font face) and ‘\F’ (font family face) Text Decoration escapes behave irregularly
         when specified within line-macro scopes.
     -   Negative scaling units return to prior lines.  Instead, mandoc truncates them to zero.

     The following features are unimplemented in mandoc:

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

SEE ALSO

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

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

     The manual page groff_mdoc(7): https://man.voidlinux.org/groff_mdoc contained in the “groff”
     package documents exactly the same language in a somewhat different style.

HISTORY

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

AUTHORS

     The mdoc reference was written by Kristaps Dzonsons <kristaps@bsd.lv>.