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MDOC(7)                Miscellaneous Information Manual                MDOC(7)

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 arguments 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
     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.

     %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, unless Fl is more appropriate.  Also useful when
          specifying configuration options or keys.

          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
                .Cm IdentityFile Pa ~/.ssh/id_rsa
                .Cm LogLevel Dv DEBUG

     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.  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 year-month-day
                 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.  Prints a fixed-width hyphen `-' 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.

          Examples:
                .Fl R Op Fl H | L | P
                .Op Fl 1AaCcdFfgHhikLlmnopqRrSsTtux
                .Fl type Cm d Fl name Pa CVS
                .Fl Ar signal_number
                .Fl o Fl

          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 ...
          Designate an internal or interactive command.  This is similar to Cm
          but used for instructions rather than values.

          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 http://bsd.lv "The BSD.lv Project"
                .Lk http://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.

             -isoC-2018
                             The fourth 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     IEEE Std 1003.1-1990 ("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.1b")
             -p1003.1b       IEEE Std 1003.1b ("POSIX.1b")
                             Real-time extensions.

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

             -p1003.1i-95    IEEE Std 1003.1i-1995 ("POSIX.1i")
                             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          Version 1 of the Single UNIX Specification
                             ("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         X/Open System Interfaces and Headers Issue 4,
                             Version 2 ("XSH4.2")

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

             -p1003.1g-2000  IEEE Std 1003.1g-2000 ("POSIX.1g")
                             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          Version 4 of the Single UNIX Specification
                             ("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 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.

     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
           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.

   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:

     -   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 "Epoch" is printed.
     -   Lk only accepts a single link-name argument; the remainder is
         misformatted.
     -   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.
     -   %C is not implemented (up to and including groff-1.22.2).
     -   `\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:
     http://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.

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>.

NetBSD 8.99.34                 February 7, 2019                 NetBSD 8.99.34