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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, & 9 only.
           .\" Not used in OpenBSD.
           .Sh SYNOPSIS
           .Nm progname
           .Op Fl options
           .Ar
           .Sh DESCRIPTION
           The
           .Nm
           utility processes files ...
           .\" .Sh IMPLEMENTATION NOTES
           .\" Not used in OpenBSD.
           .\" .Sh RETURN VALUES
           .\" For sections 2, 3, & 9 only.
           .\" .Sh ENVIRONMENT
           .\" For sections 1, 6, 7, & 8 only.
           .\" .Sh FILES
           .\" .Sh EXIT STATUS
           .\" For sections 1, 6, & 8 only.
           .\" .Sh EXAMPLES
           .\" .Sh DIAGNOSTICS
           .\" For sections 1, 4, 6, 7, & 8 only.
           .\" .Sh ERRORS
           .\" For sections 2, 3, & 9 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

       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.

       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 conditions.  This is most useful in section 4 manuals.
       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 error handling in sections 2, 3, 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.

       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 [volume | 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, Lp           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)
     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
     br               force output line break in text mode (no arguments)
     sp               force vertical space: [height]

   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)
     Ft               function type (>0 arguments)
     Fo, Fc           function block: funcname
     Fn               function name: [functype] funcname [[argtype] argname]
     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 [name]
     Mt               ``mailto'' hyperlink: address
     Cd               kernel configuration declaration (>0 arguments)
     Ad               memory address (>0 arguments)
     Ms               mathematical symbol (>0 arguments)
     Tn               tradename (>0 arguments)

   Physical markup
     Em               italic font or underline (emphasis) (>0 arguments)
     Sy               boldface font (symbolic) (>0 arguments)
     Li               typewriter font (literal) (>0 arguments)
     No               return to roman font (normal) (no 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'
     Ql               single-quoted literal text: `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)
     Ux               UNIX
     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
     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
     Book title of an Rs block.  This macro may also be used in a non-
     bibliographic context when referring to book titles.

   %C
     Publication city or location of an Rs block.

   %D
     Publication date of an Rs block.  Recommended formats of arguments are
     month day, year or just year.

   %I
     Publisher or issuer name of an Rs block.

   %J
     Journal name of an Rs block.

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

   %O
     Optional information of an Rs block.

   %P
     Book or journal page number of an Rs block.

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

   %R
     Technical report name of an Rs block.

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

   %U
     URI of reference document.

   %V
     Volume number of an Rs block.

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

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

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

   An
     Author name.  Can be used both for the authors of the program, function,
     or driver documented in the manual, or for the authors of the manual
     itself.  Requires either the name of an author or one of the following
     arguments:

           -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 kristapsATbsd.lv

   Ao
     Begin a block enclosed by angle brackets.  Does not have any head
     arguments.

     Examples:
           .Fl -key= Ns Ao Ar val Ac

     See also Aq.

   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
     Encloses its arguments in angle brackets.

     Examples:
           .Fl -key= Ns Aq Ar val

     Remarks: this macro is often abused for rendering URIs, which should
     instead use Lk or Mt, or to note pre-processor ``#include'' statements,
     which should use In.

     See also Ao.

   Ar
     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
     Formats an AT&T version.  Accepts one optional argument:

           v[1-7] | 32v   A version of AT&T UNIX.
           III            AT&T System III UNIX.
           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, Ox, and Ux.

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

   Bd
     Begin a display block.  Its syntax is as follows:

           .Bd -type [-offset width] [-compact]

     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
                          centre-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
                          centre 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 width using the syntax described in Scaling
                          Widths.

                          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
     Change the font mode for a scoped block of text.  Its syntax is as
     follows:

           .Bf [-emphasis | -literal | -symbolic | Em | Li | Sy]

     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
     For each macro, keep its output together on the same output line, until
     the end of the macro or the end of the input line is reached, whichever
     comes first.  Line breaks in text lines are unaffected.  The syntax is as
     follows:

           .Bk -words

     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
     Begin a list.  Lists consist of items specified using the It macro,
     containing a head or a body or both.  The list syntax is as follows:

           .Bl -type [-width val] [-offset val] [-compact] [HEAD ...]

     The list type is mandatory and must be specified first.  The -width and
     -offset arguments accept Scaling Widths 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, each argument specifies the width of
                         one column, using either the Scaling Widths syntax or
                         the string length of the argument.  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
     Begin a block enclosed by square brackets.  Does not have any head
     arguments.

     Examples:
           .Bo 1 ,
           .Dv BUFSIZ Bc

     See also Bq.

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

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

     See also Brq.

   Brq
     Encloses its arguments in curly braces.

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

     See also Bro.

   Bsx
     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, Ox, and Ux.

   Bt
     Prints ``is currently in beta test.''

   Bx
     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, Ox, and Ux.

   Cd
     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
     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
     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
     Switch debugging mode.  Its syntax is as follows:

           .Db on | off

     This macro is ignored by mandoc(1).

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

   Dd
     Document date.  This is the mandatory first macro of any mdoc manual.
     Its syntax is as follows:

           .Dd month day, year

     The month is the full English month name, the day is an optionally zero-
     padded numeral, 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.
        -   A few alternative date formats are accepted as well and converted
            to the standard form.
        -   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 $Mdocdate: July 21 2007$
           .Dd July 21, 2007

     See also Dt and Os.

   Dl
     One-line intended 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 Bd and D1.

   Do
     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
     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
     Document title.  This is the mandatory second macro of any mdoc file.
     Its syntax is as follows:

           .Dt [title [section [volume] [arch]]]

     Its arguments are as follows:

       title   The document's title (name), defaulting to ``UNKNOWN'' if
               unspecified.  It should be capitalised.

       section
               The manual section.  This may be one of 1 (utilities), 2
               (system calls), 3 (libraries), 3p (Perl libraries), 4
               (devices), 5 (file formats), 6 (games), 7 (miscellaneous), 8
               (system utilities), 9 (kernel functions), X11 (X Window
               System), X11R6 (X Window System), unass (unassociated), local
               (local system), draft (draft manual), or paper (paper).  It
               should correspond to the manual's filename suffix and defaults
               to ``1'' if unspecified.

       volume  This overrides the volume inferred from section.  This field is
               optional, and if specified, must be one of USD (users'
               supplementary documents), PS1 (programmers' supplementary
               documents), AMD (administrators' supplementary documents), SMM
               (system managers' manuals), URM (users' reference manuals), PRM
               (programmers' reference manuals), KM (kernel manuals), IND
               (master index), MMI (master index), LOCAL (local manuals), LOC
               (local manuals), or CON (contributed manuals).

       arch    This specifies the machine architecture a manual page applies
               to, where relevant, for example alpha, amd64, i386, or sparc64.
               The list of supported architectures varies by operating system.
               For the full list of all architectures recognized by mandoc(1),
               see the file arch.in in the source distribution.

     Examples:
           .Dt FOO 1
           .Dt FOO 4 KM
           .Dt FOO 9 i386

     See also Dd and Os.

   Dv
     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 and Va for variable
     symbols.

   Dx
     Format the DragonFly BSD 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, Ox, and Ux.

   Ec
     Close a scope started by Eo.  Its syntax is as follows:

           .Ec [TERM]

     The TERM 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 Bl and It.

   Em
     Denotes text that should be emphasised.  Note that this is a presentation
     term and should not be used for stylistically decorating technical terms.
     Depending on the output device, this is usually represented using an
     italic font or underlined characters.

     Examples:
           .Em Warnings!
           .Em Remarks:

     See also Bf, Li, No, and Sy.

   En
     This macro is obsolete and not implemented in mandoc(1).

   Eo
     An arbitrary enclosure.  Its syntax is as follows:

           .Eo [TERM]

     The TERM argument is used as the enclosure head, for example, specifying
     \(lq will emulate Do.

   Er
     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
     This macro is obsolete and not implemented.

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

     Examples:
           .Ev DISPLAY
           .Ev PATH

     See also Dv for general constants.

   Ex
     Insert a standard sentence regarding command exit values of 0 on success
     and >0 on failure.  This is most often used in section 1, 6, and 8 manual
     pages.  Its syntax is as follows:

           .Ex -std [utility ...]

     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
     Function argument.  Its syntax is as follows:

           .Fa [argtype] argname

     This may be invoked for names with or without the corresponding type.  It
     is also used to specify the field name of a structure.  Most often, the
     Fa macro is used in the SYNOPSIS within Fo section when documenting
     multi-line function prototypes.  If invoked with multiple arguments, the
     arguments are separated by a comma.  Furthermore, if the following macro
     is another Fa, the last argument will also have a trailing comma.

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

     See also Fo.

   Fc
     End a function context started by Fo.

   Fd
     Historically used to document include files.  This usage has been
     deprecated in favour of In.  Do not use this macro.

     See also MANUAL STRUCTURE and In.

   Fl
     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
     A function name.  Its syntax is as follows:

           .Fn [functype] funcname [[argtype] argname]

     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
     Begin a function block.  This is a multi-line version of Fn.  Its syntax
     is as follows:

           .Fo funcname

     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
     This macro is obsolete and not implemented in mandoc(1).

     It was used to show function return values.  The syntax was:

           .Fr value

   Ft
     A function type.  Its syntax is as follows:

           .Ft functype

     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
     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, Ox, and Ux.

   Hf
     This macro is not implemented in mandoc(1).

     It was used to include the contents of a (header) file literally.  The
     syntax was:

           .Hf filename

   Ic
     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 Bd -literal or D1 is preferred for displaying code; the
     Ic macro is used when referring to specific instructions.

   In
     An ``include'' file.  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.  This is most often used in section
     2, 3, and 9 manual pages.

     Examples:
           .In sys/types.h

     See also MANUAL STRUCTURE.

   It
     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 [<TAB> cell ...]
           .It cell [Ta 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 tabs or by the special Ta block macro.  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 Ta is only recognised as a macro
     when called by other macros, not 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 semicolon whitespace except for the last.

     See also Bl.

   Lb
     Specify a library.  The syntax is as follows:

           .Lb library

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

     Examples:
           .Lb libz
           .Lb mdoc

   Li
     Denotes text that should be in a literal font mode.  Note that this is a
     presentation term and should not be used for stylistically decorating
     technical terms.

     On terminal output devices, this is often indistinguishable from normal
     text.

     See also Bf, Em, No, and Sy.

   Lk
     Format a hyperlink.  Its syntax is as follows:

           .Lk uri [name]

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

     See also Mt.

   Lp
     Synonym for Pp.

   Ms
     Display a mathematical symbol.  Its syntax is as follows:

           .Ms symbol

     Examples:
           .Ms sigma
           .Ms aleph

   Mt
     Format a ``mailto:'' hyperlink.  Its syntax is as follows:

           .Mt address

     Examples:
           .Mt discussATmanpages.lv

   Nd
     A one line description of the manual's content.  This may only be invoked
     in the SYNOPSIS section subsequent the Nm macro.

     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
     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
     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, Li, 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
     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, Ox, and Ux.

   Oc
     Close multi-line Oo context.

   Oo
     Multi-line version of Op.

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

   Op
     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
     Document operating system version.  This is the mandatory third macro of
     any mdoc file.  Its syntax is as follows:

           .Os [system [version]]

     The optional system parameter specifies the relevant operating system or
     environment.  Left unspecified, it defaults to the local operating system
     version.  This is the suggested form.

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

     See also Dd and Dt.

   Ot
     This macro is obsolete and not implemented in mandoc(1).

     Historical mdoc(7) packages described it as ``old function type
     (FORTRAN)''.

   Ox
     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, Nx, and Ux.

   Pa
     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
     Removes the space between its argument (``prefix'') and the following
     macro.  Its syntax is as follows:

           .Pf prefix macro arguments ...

     This is equivalent to:

           .No prefix Ns macro arguments ...

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

     See also Ns and Sm.

   Po
     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) or lists (Bl) unless the -compact flag is given.

   Pq
     Parenthesised enclosure.

     See also Po.

   Qc
     Close quoted context opened by Qo.

   Ql
     Format a single-quoted literal.  See also Qq and Sq.

   Qo
     Multi-line version of Qq.

   Qq
     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, Massachusettes
           .%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
     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.  Its syntax is as follows:

           .Rv -std [function ...]

     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
     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
     Switches the spacing mode for output generated from macros.  Its syntax
     is as follows:

           .Sm on | off

     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.

   So
     Multi-line version of Sq.

   Sq
     Encloses its arguments in `typewriter' single-quotes.

     See also Dq, Qq, and So.

   Ss
     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
     Replace an abbreviation for a standard with the full form.  The following
     standards are recognised:

     -p1003.1-88      IEEE Std 1003.1-1988 (``POSIX.1'')
     -p1003.1-90      IEEE Std 1003.1-1990 (``POSIX.1'')
     -p1003.1-96      ISO/IEC 9945-1:1996 (``POSIX.1'')
     -p1003.1-2001    IEEE Std 1003.1-2001 (``POSIX.1'')
     -p1003.1-2004    IEEE Std 1003.1-2004 (``POSIX.1'')
     -p1003.1-2008    IEEE Std 1003.1-2008 (``POSIX.1'')
     -p1003.1         IEEE Std 1003.1 (``POSIX.1'')
     -p1003.1b        IEEE Std 1003.1b (``POSIX.1'')
     -p1003.1b-93     IEEE Std 1003.1b-1993 (``POSIX.1'')
     -p1003.1c-95     IEEE Std 1003.1c-1995 (``POSIX.1'')
     -p1003.1g-2000   IEEE Std 1003.1g-2000 (``POSIX.1'')
     -p1003.1i-95     IEEE Std 1003.1i-1995 (``POSIX.1'')
     -p1003.2-92      IEEE Std 1003.2-1992 (``POSIX.2'')
     -p1003.2a-92     IEEE Std 1003.2a-1992 (``POSIX.2'')
     -p1387.2-95      IEEE Std 1387.2-1995 (``POSIX.7.2'')
     -p1003.2         IEEE Std 1003.2 (``POSIX.2'')
     -p1387.2         IEEE Std 1387.2 (``POSIX.7.2'')
     -isoC            ISO/IEC 9899:1990 (``ISO C90'')
     -isoC-90         ISO/IEC 9899:1990 (``ISO C90'')
     -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'')
     -isoC-2011       ISO/IEC 9899:2011 (``ISO C11'')
     -iso9945-1-90    ISO/IEC 9945-1:1990 (``POSIX.1'')
     -iso9945-1-96    ISO/IEC 9945-1:1996 (``POSIX.1'')
     -iso9945-2-93    ISO/IEC 9945-2:1993 (``POSIX.2'')
     -ansiC           ANSI X3.159-1989 (``ANSI C89'')
     -ansiC-89        ANSI X3.159-1989 (``ANSI C89'')
     -ansiC-99        ANSI/ISO/IEC 9899-1999 (``ANSI C99'')
     -ieee754         IEEE Std 754-1985
     -iso8802-3       ISO 8802-3: 1989
     -iso8601         ISO 8601
     -ieee1275-94     IEEE Std 1275-1994 (``Open Firmware'')
     -xpg3            X/Open Portability Guide Issue 3 (``XPG3'')
     -xpg4            X/Open Portability Guide Issue 4 (``XPG4'')
     -xpg4.2          X/Open Portability Guide Issue 4, Version 2 (``XPG4.2'')
     -xpg4.3          X/Open Portability Guide Issue 4, Version 3 (``XPG4.3'')
     -xbd5            X/Open System Interface Definitions Issue 5 (``XBD5'')
     -xcu5            X/Open Commands and Utilities Issue 5 (``XCU5'')
     -xsh5            X/Open System Interfaces and Headers Issue 5 (``XSH5'')
     -xns5            X/Open Networking Services Issue 5 (``XNS5'')
     -xns5.2          X/Open Networking Services Issue 5.2 (``XNS5.2'')
     -xns5.2d2.0      X/Open Networking Services Issue 5.2 Draft 2.0
                      (``XNS5.2D2.0'')
     -xcurses4.2      X/Open Curses Issue 4, Version 2 (``XCURSES4.2'')
     -susv2           Version 2 of the Single UNIX Specification
     -susv3           Version 3 of the Single UNIX Specification
     -svid4           System V Interface Definition, Fourth Edition
                      (``SVID4'')

   Sx
     Reference a section or subsection in the same manual page.  The
     referenced section or subsection name must be identical to the enclosed
     argument, including whitespace.

     Examples:
           .Sx MANUAL STRUCTURE

     See also Sh and Ss.

   Sy
     Format enclosed arguments in symbolic (``boldface'').  Note that this is
     a presentation term and should not be used for stylistically decorating
     technical terms.

     See also Bf, Em, Li, and No.

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

   Tn
     Format a tradename.

     Since this macro is often implemented to use a small caps font, it has
     historically been used for acronyms (like ASCII) as well.  Such usage is
     not recommended because it would use the same macro sometimes for
     semantical annotation, sometimes for physical formatting.

     Examples:
           .Tn IBM

   Ud
     Prints out ``currently under development.''

   Ux
     Format the UNIX name.  Accepts no argument.

     Examples:
           .Ux

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

   Va
     A variable name.

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

   Vt
     A variable type.  This is also used for indicating global variables in
     the SYNOPSIS section, in which case a variable name is also specified.
     Note that it accepts 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.

     Note that this should not be confused with Ft, which is used for function
     return types.

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

     See also MANUAL STRUCTURE and Va.

   Xc
     Close a scope opened by Xo.

   Xo
     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
     Link to another manual ("cross-reference").  Its syntax is as follows:

           .Xr name section

     The name and section are the name and section of the linked manual.  If
     section is followed by non-punctuation, an Ns is inserted into the token
     stream.  This behaviour is for compatibility with GNU troff.

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

   br
     Emits a line-break.  This macro should not be used; it is implemented for
     compatibility with historical manuals.

     Consider using Pp in the event of natural paragraph breaks.

   sp
     Emits vertical space.  This macro should not be used; it is implemented
     for compatibility with historical manuals.  Its syntax is as follows:

           .sp [height]

     The height argument must be formatted as described in Scaling Widths.  If
     unspecified, sp asserts a single vertical space.

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
           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
           En        No           No         0
           Er        Yes          Yes        >0
           Es        No           No         0
           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        No           No         n
           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        No           No         n
           Ox        Yes          Yes        n
           Pa        Yes          Yes        n
           Pf        Yes          Yes        1
           Pp        No           No         0
           Rv        No           No         n
           Sm        No           No         1
           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        >0
           br        No           No         0
           sp        No           No         1

   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.  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:

           |       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 documents compatibility between mandoc and other other troff
     implementations, at this time limited to GNU troff ("groff").  The term
     "historic groff" refers to groff versions before 1.17, which featured a
     significant update of the doc.tmac file.

     Heirloom troff, the other significant troff implementation accepting
     -mdoc, is similar to historic groff.

     The following problematic behaviour is found in groff:

     -   Display macros (Bd, Dl, and D1) may not be nested.  (Historic groff
         only.)
     -   At with unknown arguments produces no output at all.  (Historic groff
         only.)  Newer groff and mandoc print "AT&T UNIX" and the arguments.
     -   Bl -column does not recognise trailing punctuation characters when
         they immediately precede tabulator characters, but treats them as
         normal text and outputs a space before them.
     -   Bd -ragged -compact does not start a new line.  (Historic groff
         only.)
     -   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.
     -   Fl does not print a dash for an empty argument.  (Historic groff
         only.)
     -   Fn does not start a new line unless invoked as the line macro in the
         SYNOPSIS section.  (Historic groff only.)
     -   Fo with non-Fa children causes inconsistent spacing between
         arguments.  In mandoc, a single space is always inserted between
         arguments.
     -   Ft in the SYNOPSIS causes inconsistent vertical spacing, depending on
         whether a prior Fn has been invoked.  See Ft and Fn for the
         normalised behaviour in mandoc.
     -   In ignores additional arguments and is not treated specially in the
         SYNOPSIS.  (Historic groff only.)
     -   It sometimes requires a -nested flag.  (Historic groff only.)  In new
         groff and mandoc, any list may be nested by default and -enum lists
         will restart the sequence only for the sub-list.
     -   Li followed by a delimiter is incorrectly used in some manuals
         instead of properly quoting that character, which sometimes works
         with historic groff.
     -   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.
     -   Historic groff only allows up to eight or nine arguments per macro
         input line, depending on the exact situation.  Providing more
         arguments causes garbled output.  The number of arguments on one
         input line is not limited with mandoc.
     -   Historic groff has many un-callable macros.  Most of these (excluding
         some block-level macros) are callable in new groff and mandoc.
     -   `|' (vertical bar) is not fully supported as a delimiter.  (Historic
         groff only.)
     -   `\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.
     -   Bd -offset center and -offset right.  Groff does not implement
         centred and flush-right rendering either, but produces large
         indentations.
     -   The `\h' (horizontal position), `\v' (vertical position), `\m' (text
         colour), `\M' (text filling colour), `\z' (zero-length character),
         `\w' (string length), `\k' (horizontal position marker), `\o' (text
         overstrike), and `\s' (text size) escape sequences are all discarded
         in mandoc.
     -   The `\f' scaling unit is accepted by mandoc, but rendered as the
         default unit.
     -   In quoted literals, groff allows pairwise double-quotes to produce a
         standalone double-quote in formatted output.  This is not supported
         by mandoc.

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

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 6.1.5                    January 3, 2012                   NetBSD 6.1.5