Provided by: groff_1.23.0-6_amd64 bug

Name

     groff_mdoc — compose BSD-style manual (man) pages with GNU roff

Synopsis

     groff -mdoc file ...

Description

     The GNU implementation of the mdoc macro package is part of the groff(1) document formatting
     system.  mdoc is a structurally- and semantically-oriented package for writing UNIX manual
     pages with troff(1).  Its predecessor, the man(7) package, primarily addressed page layout
     and presentational concerns, leaving the selection of fonts and other typesetting details to
     the individual author.  This discretion has led to divergent styling practices among authors
     using it.

     mdoc organizes its macros into domains.  The page structure domain lays out the page and
     comprises titles, section headings, displays, and lists.  The general text domain supplies
     macros to quote or style text, or to interpolate common noun phrases.  The manual domain
     offers semantic macros corresponding to the terminology used by practitioners in discussion
     of UNIX commands, routines, and files.  Manual domain macros distinguish command-line
     arguments and options, function names, function parameters, pathnames, variables, cross
     references to other manual pages, and so on.  These terms are meaningful both to the author
     and the readers of a manual page.  It is hoped that the resulting increased consistency of
     the man page corpus will enable easier translation to future documentation tools.

     Throughout UNIX documentation, a manual entry is referred to simply as a “man page”,
     regardless of its length, without gendered implication, and irrespective of the macro
     package selected for its composition.

Getting started

     The mdoc package attempts to simplify man page authorship and maintenance without requiring
     mastery of the roff language.  This document presents only essential facts about roff. For
     further background, including a discussion of basic typographical concepts like “breaking”,
     “filling”, and “adjustment”, see roff(7).  Specialized units of measurement also arise,
     namely ens, vees, inches, and points, abbreviated “n”, “v”, “i”, and “p”, respectively; see
     section Measurements of groff(7).

     For brief examples, we employ an arrow notation illustrating a transformation of input on
     the left to rendered output on the right.  Consider the .Dq macro, which double-quotes its
     arguments.
           .Dq man page  → “man page”

   Usage
     An mdoc macro is called by placing the roff control character, ‘.’ (dot) at the beginning of
     a line followed by its name.  In this document, we often discuss a macro name with this
     leading dot to identify it clearly, but the dot is not part of its name.  Space or tab
     characters can separate the dot from the macro name.  Arguments may follow, separated from
     the macro name and each other by spaces, but not tabs.  The dot at the beginning of the line
     prepares the formatter to expect a macro name.  A dot followed immediately by a newline is
     ignored; this is called the empty request.  To begin an input line with a dot (or a neutral
     apostrophe ‘'’) in some context other than a macro call, precede it with the ‘\&’ escape
     sequence; this is a dummy character, not formatted for output.  The backslash is the roff
     escape character; it can appear anywhere and it always followed by at least one more
     character.  If followed by a newline, the backslash escapes the input line break; you can
     thus keep input lines to a reasonable length without affecting their interpretation.

     Macros in GNU troff accept an unlimited number of arguments, in contrast to other troffs
     that often can't handle more than nine.  In limited cases, arguments may be continued or
     extended on the next input line without resort to the ‘\newline’ escape sequence; see
     subsection Extended arguments below.  Neutral double quotes " can be used to group multiple
     words into an argument; see subsection Passing space characters in an argument below.

     Most of mdoc's general text and manual domain macros parse their argument lists for callable
     macro names.  This means that an argument in the list matching a general text or manual
     domain macro name (and defined to be callable) will be called with the remaining arguments
     when it is encountered.  In such cases, the argument, although the name of a macro, is not
     preceded by a dot.  Macro calls can thus be nested.  This approach to macro argument
     processing is a unique characteristic of the mdoc package, not a general feature of roff
     syntax.

     For example, the option macro, .Op, may call the flag and argument macros, .Fl and .Ar, to
     specify an optional flag with an argument.
           .Op Fl s Ar bytes      → [-s bytes]
     To prevent a word from being interpreted as a macro name, precede it with the dummy
     character.
           .Op \&Fl s \&Ar bytes  → [Fl s Ar bytes]

     In this document, macros whose argument lists are parsed for callable arguments are referred
     to as parsed, and those that may be called from an argument list are referred to as
     callable.  This usage is a technical faux pas, since all mdoc macros are in fact interpreted
     (unless prevented with ‘\&’), but as it is cumbersome to constantly refer to macros as
     “being able to call other macros”, we employ the term “parsed” instead.  Except where
     explicitly stated, all mdoc macros are parsed and callable.

     In the following, we term an mdoc macro that starts a line (with a leading dot) a command if
     a distinction from those appearing as arguments of other macros is necessary.

   Passing space characters in an argument
     Sometimes it is desirable to give a macro an argument containing one or more space
     characters, for instance to specify a particular arrangement of arguments demanded by the
     macro.  Additionally, quoting multi-word arguments that are to be treated the same makes
     mdoc work faster; macros that parse arguments do so once (at most) for each.  For example,
     the function command .Fn expects its first argument to be the name of a function and any
     remaining arguments to be function parameters.  Because C language standards mandate the
     inclusion of types and identifiers in the parameter lists of function definitions, each ‘Fn’
     parameter after the first will be at least two words in length, as in “int foo”.

     There are a few ways to embed a space in a macro argument.  One is to use the unadjustable
     space escape sequence \space.  The formatter treats this escape sequence as if it were any
     other printable character, and will not break a line there as it would a word space when the
     output line is full.  This method is useful for macro arguments that are not expected to
     straddle an output line boundary, but has a drawback: this space does not adjust as others
     do when the output line is formatted.  An alternative is to use the unbreakable space escape
     sequence, ‘\~’, which cannot break but does adjust.  This groff extension is widely but not
     perfectly portable.  Another method is to enclose the string in double quotes.
           .Fn fetch char\ *str   → fetch(char *str)
           .Fn fetch char\~*str   → fetch(char *str)
           .Fn fetch "char *str"  → fetch(char *str)
     If the ‘\’ before the space in the first example or the double quotes in the third example
     were omitted, ‘.Fn’ would see three arguments, and the result would contain an undesired
     comma.
           .Fn fetch char *str    → fetch(char, *str)

   Trailing space characters
     It is wise to remove trailing spaces from the ends of input lines.  Should the need arise to
     put a formattable space at the end of a line, do so with the unadjustable or unbreakable
     space escape sequences.

   Formatting the backslash glyph
     When you need the roff escape character ‘\’ to appear in the output, use ‘\e’ or ‘\(rs’
     instead.  Technically, ‘\e’ formats the current escape character; it works reliably as long
     as no roff request is used to change it, which should never happen in man pages.  ‘\(rs’ is
     a groff special character escape sequence that explicitly formats the “reverse solidus”
     (backslash) glyph.

   Other possible pitfalls
     groff mdoc warns when an empty input line is found outside of a display, a topic presented
     in subsection Examples and displays below.  Use empty requests to space the source document
     for maintenance.

     Leading spaces cause a break and are formatted.  Avoid this behaviour if possible.
     Similarly, do not put more than one space between words in an ordinary text line; they are
     not “normalized” to a single space as other text formatters might do.

     Don't try to use the neutral double quote character ‘"’ to represent itself in an argument.
     Use the special character escape sequence ‘\(dq’ to format it.  Further, this glyph should
     not be used for conventional quotation; mdoc offers several quotation macros.  See
     subsection Enclosure and quoting macros below.

     The formatter attempts to detect the ends of sentences and by default puts the equivalent of
     two spaces between sentences on the same output line; see roff(7).  To defeat this detection
     in a parsed list of macro arguments, put ‘\&’ before the punctuation mark.  Thus,
           The
           .Ql .
           character.
           .Pp
           The
           .Ql \&.
           character.
           .Pp
           .No test .
           test
           .Pp
           .No test.
           test
     gives
           The ‘’.  character

           The ‘.’ character.

           test.  test

           test. test
     as output.  As can be seen in the first and third output lines, mdoc handles punctuation
     characters specially in macro arguments.  This will be explained in section General syntax
     below.

     A comment in the source file of a man page can begin with ‘.\"’ at the start of an input
     line, ‘\"’ after other input, or ‘\#’ anywhere (the last is a groff extension); the
     remainder of any such line is ignored.

A man page template

     Use mdoc to construct a man page from the following template.

           .\" The following three macro calls are required.
           .Dd date
           .Dt topic [section-identifier [section-keyword-or-title]]
           .Os [package-or-operating system [version-or-release]]
           .Sh Name
           .Nm topic
           .Nd summary-description
           .\" The next heading is used in sections 2 and 3.
           .\" .Sh Library
           .\" The next heading is used in sections 1-4, 6, 8, and 9.
           .Sh Synopsis
           .Sh Description
           .\" Uncomment and populate the following sections as needed.
           .\" .Sh "Implementation notes"
           .\" The next heading is used in sections 2, 3, and 9.
           .\" .Sh "Return values"
           .\" The next heading is used in sections 1, 3, 6, and 8.
           .\" .Sh Environment
           .\" .Sh Files
           .\" The next heading is used in sections 1, 6, and 8.
           .\" .Sh "Exit status"
           .\" .Sh Examples
           .\" The next heading is used in sections 1, 4, 6, 8, and 9.
           .\" .Sh Diagnostics
           .\" .Sh Compatibility
           .\" The next heading is used in sections 2, 3, 4, and 9.
           .\" .Sh Errors
           .\" .Sh "See also"
           .\" .Sh Standards
           .\" .Sh History
           .\" .Sh Authors
           .\" .Sh Caveats
           .\" .Sh Bugs

     The first items in the template are the commands .Dd, .Dt, and .Os.  They identify the page
     and are discussed below in section Title macros.

     The remaining items in the template are section headings (.Sh); of which Name and
     Description are mandatory.  These headings are discussed in section Page structure domain,
     which follows section Manual domain.  Familiarize yourself with manual domain macros first;
     we use them to illustrate the use of page structure domain macros.

Conventions

     In the descriptions of macros below, square brackets surround optional arguments.  An
     ellipsis (‘...’) represents repetition of the preceding argument zero or more times.
     Alternative values of a parameter are separated with ‘|’.  If a mandatory parameter can take
     one of several alternative values, use braces to enclose the set, with spaces and ‘|’
     separating the items.
           ztar {c | x} [-w [-y | -z]] [-f archive] member ...
     An alternative to using braces is to separately synopsize distinct operation modes,
     particularly if the list of valid optional arguments is dependent on the user's choice of a
     mandatory parameter.
           ztar c [-w [-y | -z]] [-f archive] member ...
           ztar x [-w [-y | -z]] [-f archive] member ...

     Most macros affect subsequent arguments until another macro or a newline is encountered.
     For example, ‘.Li ls Bq Ar file’ doesn't produce ‘ls [file]’, but ‘ls [file]’.
     Consequently, a warning message is emitted for many commands if the first argument is itself
     a macro, since it cancels the effect of the preceding one.  On rare occasions, you might
     want to format a word along with surrounding brackets as a literal.
           .Li "ls [file]"  → ls [file] # list any files named e, f, i, or l

     Many macros possess an implicit width, used when they are contained in lists and displays.
     If you avoid relying on these default measurements, you escape potential conflicts with
     site-local modifications of the mdoc package.  Explicit -width and -offset arguments to the
     .Bl and .Bd macros are preferable.

Title macros

     We present the mandatory title macros first due to their importance even though they
     formally belong to the page structure domain macros.  They designate the topic, date of last
     revision, and the operating system or software project associated with the page.  Call each
     once at the beginning of the document.  They populate the page headers and footers, which
     are in roff parlance termed “titles”.

     .Dd date
             This first macro of any mdoc manual records the last modification date of the
             document source.  Arguments are concatenated and separated with space characters.

             Historically, date was written in U.S. traditional format, “Month day , year” where
             Month is the full month name in English, day an integer without a leading zero, and
             year the four-digit year.  This localism is not enforced, however.  You may prefer
             ISO 8601 format, YYYY-MM-DD. A date of the form ‘$Mdocdate: Month day year $’ is
             also recognized.  It is used in OpenBSD manuals to automatically insert the current
             date when committing.

             This macro is neither callable nor parsed.

     .Dt topic [section-identifier [section-keyword-or-title]]
             topic is the subject of the man page.  A section-identifier that begins with an
             integer in the range 1–9 or is one of the words ‘unass’, ‘draft’, or ‘paper’ selects
             a predefined section title.  This use of “section” has nothing to do with the
             section headings otherwise discussed in this page; it arises from the organizational
             scheme of printed and bound Unix manuals.

             In this implementation, the following titles are defined for integral section
             numbers.

                   1   General Commands Manual
                   2   System Calls Manual
                   3   Library Functions Manual
                   4   Kernel Interfaces Manual
                   5   File Formats Manual
                   6   Games Manual
                   7   Miscellaneous Information Manual
                   8   System Manager's Manual
                   9   Kernel Developer's Manual

             A section title may be arbitrary or one of the following abbreviations.

                   USD     User's Supplementary Documents
                   PS1     Programmer's Supplementary Documents
                   AMD     Ancestral Manual Documents
                   SMM     System Manager's Manual
                   URM     User's Reference Manual
                   PRM     Programmer's Manual
                   KM      Kernel Manual
                   IND     Manual Master Index
                   LOCAL   Local Manual
                   CON     Contributed Software Manual

             For compatibility, ‘MMI’ can be used for ‘IND’, and ‘LOC’ for ‘LOCAL’.  Values from
             the previous table will specify a new section title.  If section-keyword-or-title
             designates a computer architecture recognized by groff mdoc, its value is prepended
             to the default section title as specified by the second parameter.  By default, the
             following architecture keywords are defined.

                 acorn26, acorn32, algor, alpha, amd64, amiga, amigappc, arc, arm, arm26, arm32,
                 armish, atari, aviion, beagle, bebox, cats, cesfic, cobalt, dreamcast, emips,
                 evbarm, evbmips, evbppc, evbsh3, ews4800mips, hp300, hp700, hpcarm, hpcmips,
                 hpcsh, hppa, hppa64, i386, ia64, ibmnws, iyonix, landisk, loongson, luna68k,
                 luna88k, m68k, mac68k, macppc, mips, mips64, mipsco, mmeye, mvme68k, mvme88k,
                 mvmeppc, netwinder, news68k, newsmips, next68k, ofppc, palm, pc532,
                 playstation2, pmax, pmppc, powerpc, prep, rs6000, sandpoint, sbmips, sgi,
                 sgimips, sh3, shark, socppc, solbourne, sparc, sparc64, sun2, sun3, tahoe, vax,
                 x68k, x86_64, xen, zaurus

             If a section title is not determined after the above matches have been attempted,
             section-keyword-or-title is used.

             The effects of varying ‘.Dt’ arguments on the page header content are shown below.
             Observe how ‘\&’ prevents the numeral 2 from being used to look up a predefined
             section title.

               .Dt foo 2       →  foo(2)     System Calls Manual      foo(2)
               .Dt foo 2 m68k  →  foo(2)   m68k System Calls Manual   foo(2)
               .Dt foo 2 baz   →  foo(2)     System Calls Manual      foo(2)
               .Dt foo \&2 baz →  foo(2)             baz              foo(2)
               .Dt foo "" baz  →  foo                baz                 foo
               .Dt foo M Z80   →  foo(M)             Z80              foo(M)

             roff strings define section titles and architecture identifiers.  Site-specific
             additions might be found in the file mdoc.local; see section Files below.

             This macro is neither callable nor parsed.

     .Os [operating-system-or-package-name [version-or-release]]
             This macro associates the document with a software distribution.  When composing a
             man page to be included in the base installation of an operating system, do not
             provide an argument; mdoc will supply it.  In this implementation, that default is
             “BSD”.  It may be overridden in the site configuration file, mdoc.local; see section
             Files below.  A portable software package maintaining its own man pages can supply
             its name and version number or release identifier as optional arguments.  A
             version-or-release argument should use the standard nomenclature for the software
             specified.  In the following table, recognized version-or-release arguments for some
             predefined operating systems are listed.  As with .Dt, site additions might be
             defined in mdoc.local.

                   ATT        7th, 7, III, 3, V, V.2, V.3, V.4

                   BSD        3, 4, 4.1, 4.2, 4.3, 4.3t, 4.3T, 4.3r, 4.3R, 4.4

                   NetBSD     0.8, 0.8a, 0.9, 0.9a, 1.0, 1.0a, 1.1, 1.2, 1.2a, 1.2b, 1.2c, 1.2d,
                              1.2e, 1.3, 1.3a, 1.4, 1.4.1, 1.4.2, 1.4.3, 1.5, 1.5.1, 1.5.2,
                              1.5.3, 1.6, 1.6.1, 1.6.2, 1.6.3, 2.0, 2.0.1, 2.0.2, 2.0.3, 2.1,
                              3.0, 3.0.1, 3.0.2, 3.0.3, 3.1, 3.1.1, 4.0, 4.0.1, 5.0, 5.0.1,
                              5.0.2, 5.1, 5.1.2, 5.1.3, 5.1.4, 5.2, 5.2.1, 5.2.2, 6.0, 6.0.1,
                              6.0.2, 6.0.3, 6.0.4, 6.0.5, 6.0.6, 6.1, 6.1.1, 6.1.2, 6.1.3, 6.1.4,
                              6.1.5, 7.0, 7.0.1, 7.0.2, 7.1, 7.1.1, 7.1.2, 7.2, 8.0, 8.1

                   FreeBSD    1.0, 1.1, 1.1.5, 1.1.5.1, 2.0, 2.0.5, 2.1, 2.1.5, 2.1.6, 2.1.7,
                              2.2, 2.2.1, 2.2.2, 2.2.5, 2.2.6, 2.2.7, 2.2.8, 2.2.9, 3.0, 3.1,
                              3.2, 3.3, 3.4, 3.5, 4.0, 4.1, 4.1.1, 4.2, 4.3, 4.4, 4.5, 4.6,
                              4.6.2, 4.7, 4.8, 4.9, 4.10, 4.11, 5.0, 5.1, 5.2, 5.2.1, 5.3, 5.4,
                              5.5, 6.0, 6.1, 6.2, 6.3, 6.4, 7.0, 7.1, 7.2, 7.3, 7.4, 8.0, 8.1,
                              8.2, 8.3, 8.4, 9.0, 9.1, 9.2, 9.3, 10.0, 10.1, 10.2, 10.3, 10.4,
                              11.0, 11.1, 11.2, 11.3, 12.0, 12.1

                   OpenBSD    2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2,
                              3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5,
                              4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8,
                              5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6

                   DragonFly  1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.8.1, 1.9, 1.10,
                              1.11, 1.12, 1.12.2, 1.13, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7,
                              2.8, 2.9, 2.9.1, 2.10, 2.10.1, 2.11, 2.12, 2.13, 3.0, 3.0.1, 3.0.2,
                              3.1, 3.2, 3.2.1, 3.2.2, 3.3, 3.4, 3.4.1, 3.4.2, 3.4.3, 3.5, 3.6,
                              3.6.1, 3.6.2, 3.7, 3.8, 3.8.1, 3.8.2, 4.0, 4.0.1, 4.0.2, 4.0.3,
                              4.0.4, 4.0.5, 4.0.6, 4.1, 4.2, 4.2.1, 4.2.2, 4.2.3, 4.2.4, 4.3,
                              4.4, 4.4.1, 4.4.2, 4.4.3, 4.5, 4.6, 4.6.1, 4.6.2, 4.7, 4.8, 4.8.1,
                              4.9, 5.0, 5.0.1, 5.0.2, 5.1, 5.2, 5.2.1, 5.2.2, 5.3, 5.4, 5.4.1,
                              5.4.2, 5.4.3, 5.5, 5.6, 5.6.1, 5.6.2

                   Darwin     8.0.0, 8.1.0, 8.2.0, 8.3.0, 8.4.0, 8.5.0, 8.6.0, 8.7.0, 8.8.0,
                              8.9.0, 8.10.0, 8.11.0, 9.0.0, 9.1.0, 9.2.0, 9.3.0, 9.4.0, 9.5.0,
                              9.6.0, 9.7.0, 9.8.0, 10.0.0, 10.1.0, 10.2.0, 10.3.0, 10.4.0,
                              10.5.0, 10.6.0, 10.7.0, 10.8.0, 11.0.0, 11.1.0, 11.2.0, 11.3.0,
                              11.4.0, 11.5.0, 12.0.0, 12.1.0, 12.2.0, 13.0.0, 13.1.0, 13.2.0,
                              13.3.0, 13.4.0, 14.0.0, 14.1.0, 14.2.0, 14.3.0, 14.4.0, 14.5.0,
                              15.0.0, 15.1.0, 15.2.0, 15.3.0, 15.4.0, 15.5.0, 15.6.0, 16.0.0,
                              16.1.0, 16.2.0, 16.3.0, 16.4.0, 16.5.0, 16.6.0, 17.0.0, 17.1.0,
                              17.2.0, 17.3.0, 17.4.0, 17.5.0, 17.6.0, 17.7.0, 18.0.0, 18.1.0,
                              18.2.0, 18.3.0, 18.4.0, 18.5.0, 18.6.0, 18.7.0, 19.0.0, 19.1.0,
                              19.2.0

             Historically, the first argument used with .Dt was BSD or ATT.  An unrecognized
             version argument after ATT is replaced with “UNIX”; for other predefined
             abbreviations, it is ignored and a warning diagnostic emitted.  Otherwise,
             unrecognized arguments are displayed verbatim in the page footer.  For instance,
             this page uses “.Os groff 1.23.0” whereas a locally produced page might employ “.Os
             "UXYZ CS Department"”, omitting versioning.

             This macro is neither callable nor parsed.

Introduction to manual and general text domains

   What's in a Name...
     The manual domain macro names are derived from the day to day informal language used to
     describe commands, subroutines and related files.  Slightly different variations of this
     language are used to describe the three different aspects of writing a man page.  First,
     there is the description of mdoc macro command usage.  Second is the description of a UNIX
     command with mdoc macros, and third, the description of a command to a user in the verbal
     sense; that is, discussion of a command in the text of a man page.

     In the first case, troff macros are themselves a type of command; the general syntax for a
     troff command is:

           .Xx argument1 argument2 ...

     ‘.Xx’ is a macro command, and anything following it are arguments to be processed.  In the
     second case, the description of a UNIX command using the manual domain macros is a bit more
     involved; a typical Synopsis command line might be displayed as:

           filter [-flag] ⟨infile⟩ ⟨outfile⟩

     Here, filter is the command name and the bracketed string -flag is a flag argument
     designated as optional by the option brackets.  In mdoc terms, ⟨infile⟩ and ⟨outfile⟩ are
     called meta arguments; in this example, the user has to replace the meta expressions given
     in angle brackets with real file names.  Note that in this document meta arguments are used
     to describe mdoc commands; in most man pages, meta variables are not specifically written
     with angle brackets.  The macros that formatted the above example:

           .Nm filter
           .Op Fl flag
           .Ao Ar infile Ac Ao Ar outfile Ac

     In the third case, discussion of commands and command syntax includes both examples above,
     but may add more detail.  The arguments ⟨infile⟩ and ⟨outfile⟩ from the example above might
     be referred to as operands or file arguments.  Some command-line argument lists are quite
     long:

           make  [-eiknqrstv] [-D variable] [-d flags] [-f makefile] [-I directory] [-j max_jobs]
                 [variable=value] [target ...]

     Here one might talk about the command make and qualify the argument, makefile, as an
     argument to the flag, -f, or discuss the optional file operand target.  In the verbal
     context, such detail can prevent confusion, however the mdoc package does not have a macro
     for an argument to a flag.  Instead the ‘Ar’ argument macro is used for an operand or file
     argument like target as well as an argument to a flag like variable.  The make command line
     was produced from:

           .Nm make
           .Op Fl eiknqrstv
           .Op Fl D Ar variable
           .Op Fl d Ar flags
           .Op Fl f Ar makefile
           .Op Fl I Ar directory
           .Op Fl j Ar max_jobs
           .Op Ar variable Ns = Ns Ar value
           .Bk
           .Op Ar target ...
           .Ek

     The ‘.Bk’ and ‘.Ek’ macros are explained in Keeps.

   General Syntax
     The manual domain and general text domain macros share a similar syntax with a few minor
     deviations; most notably, ‘.Ar’, ‘.Fl’, ‘.Nm’, and ‘.Pa’ differ only when called without
     arguments; and ‘.Fn’ and ‘.Xr’ impose an order on their argument lists.  All manual domain
     macros are capable of recognizing and properly handling punctuation, provided each
     punctuation character is separated by a leading space.  If a command is given:

           .Ar sptr, ptr),

     The result is:

           sptr, ptr),

     The punctuation is not recognized and all is output in the font used by ‘.Ar’.  If the
     punctuation is separated by a leading white space:

           .Ar sptr , ptr ) ,

     The result is:

           sptr, ptr),

     The punctuation is now recognized and output in the default font distinguishing it from the
     argument strings.  To remove the special meaning from a punctuation character, escape it
     with ‘\&’.

     The following punctuation characters are recognized by mdoc:

               .         ,         :         ;         (
               )         [         ]         ?         !

     troff is limited as a macro language, and has difficulty when presented with a string
     containing certain mathematical, logical, or quotation character sequences:

                 {+,-,/,*,%,<,>,<=,>=,=,==,&,`,',"}

     The problem is that troff may assume it is supposed to actually perform the operation or
     evaluation suggested by the characters.  To prevent the accidental evaluation of these
     characters, escape them with ‘\&’.  Typical syntax is shown in the first manual domain macro
     displayed below, ‘.Ad’.

Manual domain

   Addresses
     The address macro identifies an address construct.

           Usage: .Ad ⟨address⟩ ...

                    .Ad addr1           addr1
                    .Ad addr1 .         addr1.
                    .Ad addr1 , file2   addr1, file2
                    .Ad f1 , f2 , f3 :  f1, f2, f3:
                    .Ad addr ) ) ,      addr)),

     The default width is 12n.

   Author Name
     The ‘.An’ macro is used to specify the name of the author of the item being documented, or
     the name of the author of the actual manual page.

           Usage: .An ⟨author name⟩ ...

                    .An "Joe Author"        Joe Author

                    .An "Joe Author" ,      Joe Author,

                    .An "Joe Author" Aq nobody@FreeBSD.org
                                            Joe Author <nobody@FreeBSD.org>

                    .An "Joe Author" ) ) ,  Joe Author)),

     The default width is 12n.

     In a section titled “Authors”, ‘An’ causes a break, allowing each new name to appear on its
     own line.  If this is not desirable,

           .An -nosplit

     call will turn this off.  To turn splitting back on, write

           .An -split

   Arguments
     The .Ar argument macro may be used whenever an argument is referenced.  If called without
     arguments, ‘file ...’ is output.  This places the ellipsis in italics, which is ugly and
     incorrect, and will be noticed on terminals that underline text instead of using an oblique
     typeface.  We recommend using ‘.Ar file No ...’ instead.

           Usage: .Ar [⟨argument⟩] ...

                    .Ar              file ...
                    .Ar file No ...  file ...
                    .Ar file1        file1
                    .Ar file1 .      file1.
                    .Ar file1 file2  file1 file2
                    .Ar f1 f2 f3 :   f1 f2 f3:
                    .Ar file ) ) ,   file)),

     The default width is 12n.

   Configuration Declaration (Section Four Only)
     The ‘.Cd’ macro is used to demonstrate a config(8) declaration for a device interface in a
     section four manual.

           Usage: .Cd ⟨argument⟩ ...

                    .Cd "device le0 at scode?"  device le0 at scode?

     In a section titled “Synopsis”, ‘Cd’ causes a break before and after its arguments.

     The default width is 12n.

   Command Modifiers
     The command modifier is identical to the ‘.Fl’ (flag) command with the exception that the
     ‘.Cm’ macro does not assert a dash in front of every argument.  Traditionally flags are
     marked by the preceding dash, however, some commands or subsets of commands do not use them.
     Command modifiers may also be specified in conjunction with interactive commands such as
     editor commands.  See Flags.

     The default width is 10n.

   Defined Variables
     A variable (or constant) that is defined in an include file is specified by the macro ‘.Dv’.

           Usage: .Dv ⟨defined-variable⟩ ...

                    .Dv MAXHOSTNAMELEN  MAXHOSTNAMELEN
                    .Dv TIOCGPGRP )     TIOCGPGRP)

     The default width is 12n.

   Errnos
     The ‘.Er’ errno macro specifies the error return value for section 2, 3, and 9 library
     routines.  The second example below shows ‘.Er’ used with the ‘.Bq’ general text domain
     macro, as it would be used in a section two manual page.

           Usage: .Er ⟨errno type⟩ ...

                    .Er ENOENT      ENOENT
                    .Er ENOENT ) ;  ENOENT);
                    .Bq Er ENOTDIR  [ENOTDIR]

     The default width is 17n.

   Environment Variables
     The ‘.Ev’ macro specifies an environment variable.

           Usage: .Ev ⟨argument⟩ ...

                    .Ev DISPLAY        DISPLAY
                    .Ev PATH .         PATH.
                    .Ev PRINTER ) ) ,  PRINTER)),

     The default width is 15n.

   Flags
     The ‘.Fl’ macro handles command-line flags.  It prepends a dash, ‘-’, to the flag.  For
     interactive command flags that are not prepended with a dash, the ‘.Cm’ (command modifier)
     macro is identical, but without the dash.

           Usage: .Fl ⟨argument⟩ ...

                    .Fl          -
                    .Fl cfv      -cfv
                    .Fl cfv .    -cfv.
                    .Cm cfv .    cfv.
                    .Fl s v t    -s -v -t
                    .Fl - ,      --,
                    .Fl xyz ) ,  -xyz),
                    .Fl |        - |

     The ‘.Fl’ macro without any arguments results in a dash representing stdin/stdout.  Note
     that giving ‘.Fl’ a single dash will result in two dashes.

     The default width is 12n.

   Function Declarations
     The ‘.Fd’ macro is used in the Synopsis section with section two or three functions.  It is
     neither callable nor parsed.

           Usage: .Fd ⟨argument⟩ ...

                    .Fd "#include <sys/types.h>"  #include <sys/types.h>

     In a section titled “Synopsis”, ‘Fd’ causes a break if a function has already been presented
     and a break has not occurred, leaving vertical space between one function declaration and
     the next.

     In a section titled “Synopsis”, the ‘In’ macro represents the #include statement, and is the
     short form of the above example.  It specifies the C header file as being included in a
     C program.  It also causes a break.

     While not in the “Synopsis” section, it represents the header file enclosed in angle
     brackets.

           Usage: .In ⟨header file⟩

                    .In stdio.h  <stdio.h>
                    .In stdio.h  <stdio.h>

   Function Types
     This macro is intended for the “Synopsis” section.  It may be used anywhere else in the man
     page without problems, but its main purpose is to present the function type (in BSD kernel
     normal form) for the “Synopsis” of sections two and three.  (It causes a break, allowing the
     function name to appear on the next line.)

           Usage: .Ft ⟨type⟩ ...

                    .Ft struct stat  struct stat

   Functions (Library Routines)
     The ‘.Fn’ macro is modeled on ANSI C conventions.

           Usage: .Fn ⟨function⟩ [⟨parameter⟩] ...

                    .Fn getchar              getchar()
                    .Fn strlen ) ,           strlen()),
                    .Fn align "char *ptr" ,  align(char *ptr),

     Note that any call to another macro signals the end of the ‘.Fn’ call (it will insert a
     closing parenthesis at that point).

     For functions with many parameters (which is rare), the macros ‘.Fo’ (function open) and
     ‘.Fc’ (function close) may be used with ‘.Fa’ (function argument).

     Example:

           .Ft int
           .Fo res_mkquery
           .Fa "int op"
           .Fa "char *dname"
           .Fa "int class"
           .Fa "int type"
           .Fa "char *data"
           .Fa "int datalen"
           .Fa "struct rrec *newrr"
           .Fa "char *buf"
           .Fa "int buflen"
           .Fc

     Produces:

           int res_mkquery(int op, char *dname, int class, int type, char *data, int datalen,
           struct rrec *newrr, char *buf, int buflen)

     Typically, in a “Synopsis” section, the function delcaration will begin the line.  If more
     than one function is presented in the “Synopsis” section and a function type has not been
     given, a break will occur, leaving vertical space between the current and prior function
     names.

     The default width values of ‘.Fn’ and ‘.Fo’ are 12n and 16n, respectively.

   Function Arguments
     The ‘.Fa’ macro is used to refer to function arguments (parameters) outside of the Synopsis
     section of the manual or inside the Synopsis section if the enclosure macros ‘.Fo’ and ‘.Fc’
     instead of ‘.Fn’ are used.  ‘.Fa’ may also be used to refer to structure members.

           Usage: .Fa ⟨function argument⟩ ...

                    .Fa d_namlen ) ) ,  d_namlen)),
                    .Fa iov_len         iov_len

     The default width is 12n.

   Return Values
     The ‘.Rv’ macro generates text for use in the Return values section.

           Usage: .Rv [-std] [⟨function⟩ ...]

     For example, ‘.Rv -std atexit’ produces:

           The atexit() function returns the value 0 if successful; otherwise the value -1 is
           returned and the global variable errno is set to indicate the error.

     The -std option is valid only for manual page sections 2 and 3.  Currently, this macro does
     nothing if used without the -std flag.

   Exit Status
     The ‘.Ex’ macro generates text for use in the Diagnostics section.

           Usage: .Ex [-std] [⟨utility⟩ ...]

     For example, ‘.Ex -std cat’ produces:

           The cat utility exits 0 on success, and >0 if an error occurs.

     The -std option is valid only for manual page sections 1, 6 and 8.  Currently, this macro
     does nothing if used without the -std flag.

   Interactive Commands
     The ‘.Ic’ macro designates an interactive or internal command.

           Usage: .Ic ⟨argument⟩ ...

                    .Ic :wq                :wq
                    .Ic "do while {...}"   do while {...}
                    .Ic setenv , unsetenv  setenv, unsetenv

     The default width is 12n.

   Library Names
     The ‘.Lb’ macro is used to specify the library where a particular function is compiled in.

           Usage: .Lb ⟨argument⟩ ...

     Available arguments to ‘.Lb’ and their results are:

           libarchive     Reading and Writing Streaming Archives Library (libarchive, -larchive)
           libarm         ARM Architecture Library (libarm, -larm)
           libarm32       ARM32 Architecture Library (libarm32, -larm32)
           libbluetooth   Bluetooth Library (libbluetooth, -lbluetooth)
           libbsm         Basic Security Module Library (libbsm, -lbsm)
           libc           Standard C Library (libc, -lc)
           libc_r         Reentrant C Library (libc_r, -lc_r)
           libcalendar    Calendar Arithmetic Library (libcalendar, -lcalendar)
           libcam         Common Access Method User Library (libcam, -lcam)
           libcdk         Curses Development Kit Library (libcdk, -lcdk)
           libcipher      FreeSec Crypt Library (libcipher, -lcipher)
           libcompat      Compatibility Library (libcompat, -lcompat)
           libcrypt       Crypt Library (libcrypt, -lcrypt)
           libcurses      Curses Library (libcurses, -lcurses)
           libdevinfo     Device and Resource Information Utility Library (libdevinfo, -ldevinfo)
           libdevstat     Device Statistics Library (libdevstat, -ldevstat)
           libdisk        Interface to Slice and Partition Labels Library (libdisk, -ldisk)
           libdwarf       DWARF Access Library (libdwarf, -ldwarf)
           libedit        Command Line Editor Library (libedit, -ledit)
           libelf         ELF Access Library (libelf, -lelf)
           libevent       Event Notification Library (libevent, -levent)
           libfetch       File Transfer Library for URLs (libfetch, -lfetch)
           libform        Curses Form Library (libform, -lform)
           libgeom        Userland API Library for kernel GEOM subsystem (libgeom, -lgeom)
           libgpib        General-Purpose Instrument Bus (GPIB) library (libgpib, -lgpib)
           libi386        i386 Architecture Library (libi386, -li386)
           libintl        Internationalized Message Handling Library (libintl, -lintl)
           libipsec       IPsec Policy Control Library (libipsec, -lipsec)
           libipx         IPX Address Conversion Support Library (libipx, -lipx)
           libiscsi       iSCSI protocol library (libiscsi, -liscsi)
           libjail        Jail Library (libjail, -ljail)
           libkiconv      Kernel side iconv library (libkiconv, -lkiconv)
           libkse         N:M Threading Library (libkse, -lkse)
           libkvm         Kernel Data Access Library (libkvm, -lkvm)
           libm           Math Library (libm, -lm)
           libm68k        m68k Architecture Library (libm68k, -lm68k)
           libmagic       Magic Number Recognition Library (libmagic, -lmagic)
           libmd          Message Digest (MD4, MD5, etc.) Support Library (libmd, -lmd)
           libmemstat     Kernel Memory Allocator Statistics Library (libmemstat, -lmemstat)
           libmenu        Curses Menu Library (libmenu, -lmenu)
           libnetgraph    Netgraph User Library (libnetgraph, -lnetgraph)
           libnetpgp      Netpgp signing, verification, encryption and decryption (libnetpgp,
                          -lnetpgp)
           libossaudio    OSS Audio Emulation Library (libossaudio, -lossaudio)
           libpam         Pluggable Authentication Module Library (libpam, -lpam)
           libpcap        Packet Capture Library (libpcap, -lpcap)
           libpci         PCI Bus Access Library (libpci, -lpci)
           libpmc         Performance Counters Library (libpmc, -lpmc)
           libposix       POSIX Compatibility Library (libposix, -lposix)
           libprop        Property Container Object Library (libprop, -lprop)
           libpthread     POSIX Threads Library (libpthread, -lpthread)
           libpuffs       puffs Convenience Library (libpuffs, -lpuffs)
           librefuse      File System in Userspace Convenience Library (librefuse, -lrefuse)
           libresolv      DNS Resolver Library (libresolv, -lresolv)
           librpcsec_gss  RPC GSS-API Authentication Library (librpcsec_gss, -lrpcsec_gss)
           librpcsvc      RPC Service Library (librpcsvc, -lrpcsvc)
           librt          POSIX Real-time Library (librt, -lrt)
           libsdp         Bluetooth Service Discovery Protocol User Library (libsdp, -lsdp)
           libssp         Buffer Overflow Protection Library (libssp, -lssp)
           libSystem      System Library (libSystem, -lSystem)
           libtermcap     Termcap Access Library (libtermcap, -ltermcap)
           libterminfo    Terminal Information Library (libterminfo, -lterminfo)
           libthr         1:1 Threading Library (libthr, -lthr)
           libufs         UFS File System Access Library (libufs, -lufs)
           libugidfw      File System Firewall Interface Library (libugidfw, -lugidfw)
           libulog        User Login Record Library (libulog, -lulog)
           libusbhid      USB Human Interface Devices Library (libusbhid, -lusbhid)
           libutil        System Utilities Library (libutil, -lutil)
           libvgl         Video Graphics Library (libvgl, -lvgl)
           libx86_64      x86_64 Architecture Library (libx86_64, -lx86_64)
           libz           Compression Library (libz, -lz)

     Site-specific additions might be found in the file mdoc.local; see section Files below.

     In a section titled “Library”, ‘Lb’ causes a break before and after its arguments.

   Literals
     The ‘Li’ literal macro may be used for special characters, symbolic constants, and other
     syntactical items that should be typed exactly as displayed.

           Usage: .Li ⟨argument⟩ ...

                    .Li \en          \n
                    .Li M1 M2 M3 ;   M1 M2 M3;
                    .Li cntrl-D ) ,  cntrl-D),
                    .Li 1024 ...     1024 ...

     The default width is 16n.

   Names
     The ‘Nm’ macro is used for the document title or page topic.  Upon its first call, it has
     the peculiarity of remembering its argument, which should always be the topic of the man
     page.  When subsequently called without arguments, ‘Nm’ regurgitates this initial name for
     the sole purpose of making less work for the author.  Use of ‘Nm’ is also appropriate when
     presenting a command synopsis for the topic of a man page in section 1, 6, or 8.  Its
     behavior changes when presented with arguments of various forms.

                    .Nm groff_mdoc  groff_mdoc
                    .Nm             groff_mdoc
                    .Nm \-mdoc      -mdoc
                    .Nm foo ) ) ,   foo)),
                    .Nm :           groff_mdoc:

     By default, the topic is set in boldface to reflect its prime importance in the discussion.
     Cross references to other man page topics should use ‘Xr’; including a second argument for
     the section number enables them to be hyperlinked.  By default, cross-referenced topics are
     set in italics to avoid cluttering the page with boldface.

     The default width is 10n.

   Options
     The ‘.Op’ macro places option brackets around any remaining arguments on the command line,
     and places any trailing punctuation outside the brackets.  The macros ‘.Oo’ and ‘.Oc’ (which
     produce an opening and a closing option bracket, respectively) may be used across one or
     more lines or to specify the exact position of the closing parenthesis.

           Usage: .Op [⟨option⟩] ...

                    .Op                                []
                    .Op Fl k                           [-k]
                    .Op Fl k ) .                       [-k]).
                    .Op Fl k Ar kookfile               [-k kookfile]
                    .Op Fl k Ar kookfile ,             [-k kookfile],
                    .Op Ar objfil Op Ar corfil         [objfil [corfil]]
                    .Op Fl c Ar objfil Op Ar corfil ,  [-c objfil [corfil]],
                    .Op word1 word2                    [word1 word2]
                    .Li .Op Oo Ao option Ac Oc ...     .Op [⟨option⟩] ...

     Here a typical example of the ‘.Oo’ and ‘.Oc’ macros:

           .Oo
           .Op Fl k Ar kilobytes
           .Op Fl i Ar interval
           .Op Fl c Ar count
           .Oc

     Produces:

           [[-k kilobytes] [-i interval] [-c count]]

     The default width values of ‘.Op’ and ‘.Oo’ are 14n and 10n, respectively.

   Pathnames
     The ‘.Pa’ macro formats file specifications.  If called without arguments, ‘~’ (recognized
     by many shells) is output, representing the user's home directory.

           Usage: .Pa [⟨pathname⟩] ...

                    .Pa                    ~
                    .Pa /usr/share         /usr/share
                    .Pa /tmp/fooXXXXX ) .  /tmp/fooXXXXX).

     The default width is 32n.

   Standards
     The ‘.St’ macro replaces standard abbreviations with their formal names.

           Usage: .St ⟨abbreviation⟩ ...

     Available pairs for “Abbreviation/Formal Name” are:

     ANSI/ISO C

           -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”)
           -isoC-99        ISO/IEC 9899:1999 (“ISO C99”)
           -isoC-2011      ISO/IEC 9899:2011 (“ISO C11”)

     POSIX Part 1: System API

           -iso9945-1-90   ISO/IEC 9945-1:1990 (“POSIX.1”)
           -iso9945-1-96   ISO/IEC 9945-1:1996 (“POSIX.1”)
           -p1003.1        IEEE Std 1003.1 (“POSIX.1”)
           -p1003.1-88     IEEE Std 1003.1-1988 (“POSIX.1”)
           -p1003.1-90     ISO/IEC 9945-1:1990 (“POSIX.1”)
           -p1003.1-96     ISO/IEC 9945-1:1996 (“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”)
           -p1003.1-2001   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”)

     POSIX Part 2: Shell and Utilities

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

     X/Open

           -susv1
           -susv2          Version 2 of the Single UNIX Specification (“SUSv2”)
           -susv3          Version 3 of the Single UNIX Specification (“SUSv3”)
           -susv4
           -svid4          System V Interface Definition, Fourth Edition (“SVID4”)
           -xbd5           X/Open Base Definitions Issue 5 (“XBD5”)
           -xcu5           X/Open Commands and Utilities Issue 5 (“XCU5”)
           -xcurses4.2     X/Open Curses Issue 4, Version 2 (“XCURSES4.2”)
           -xns5           X/Open Networking Services Issue 5 (“XNS5”)
           -xns5.2         X/Open Networking Services Issue 5.2 (“XNS5.2”)
           -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”)
           -xsh5           X/Open System Interfaces and Headers Issue 5 (“XSH5”)

     Miscellaneous

           -ieee754        IEEE Std 754-1985
           -iso8601        ISO 8601
           -iso8802-3      ISO/IEC 8802-3:1989

   Variable Types
     The ‘.Vt’ macro may be used whenever a type is referenced.  In a section titled “Synopsis”,
     ‘Vt’ causes a break (useful for old-style C variable declarations).

           Usage: .Vt ⟨type⟩ ...

                    .Vt extern char *optarg ;  extern char *optarg;
                    .Vt FILE *                 FILE *

   Variables
     Generic variable reference.

           Usage: .Va ⟨variable⟩ ...

                    .Va count             count
                    .Va settimer ,        settimer,
                    .Va "int *prt" ) :    int *prt):
                    .Va "char s" ] ) ) ,  char s])),

     The default width is 12n.

   Manual Page Cross References
     The ‘.Xr’ macro expects the first argument to be a manual page name.  The optional second
     argument, if a string (defining the manual section), is put into parentheses.

           Usage: .Xr ⟨man page name⟩ [⟨section⟩] ...

                    .Xr mdoc        mdoc
                    .Xr mdoc ,      mdoc,
                    .Xr mdoc 7      mdoc(7)
                    .Xr xinit 1x ;  xinit(1x);

     The default width is 10n.

General text domain

   AT&T Macro
           Usage: .At [⟨version⟩] ...

                    .At       AT&T UNIX
                    .At v6 .  Version 6 AT&T UNIX.

     The following values for ⟨version⟩ are possible:

           32v, v1, v2, v3, v4, v5, v6, v7, III, V, V.1, V.2, V.3, V.4

   BSD Macro
           Usage: .Bx {-alpha | -beta | -devel} ...
                  .Bx [⟨version⟩ [⟨release⟩]] ...

                    .Bx         BSD
                    .Bx 4.3 .   4.3BSD.
                    .Bx -devel  BSD (currently under development)

     ⟨version⟩ will be prepended to the string ‘BSD’.  The following values for ⟨release⟩ are
     possible:

           Reno, reno, Tahoe, tahoe, Lite, lite, Lite2, lite2

   NetBSD Macro
           Usage: .Nx [⟨version⟩] ...

                    .Nx        NetBSD
                    .Nx 1.4 .  NetBSD 1.4.

     For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section
     Title macros.

   FreeBSD Macro
           Usage: .Fx [⟨version⟩] ...

                    .Fx        FreeBSD
                    .Fx 2.2 .  FreeBSD 2.2.

     For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section
     Title macros.

   DragonFly Macro
           Usage: .Dx [⟨version⟩] ...

                    .Dx        DragonFly
                    .Dx 1.4 .  DragonFly 1.4.

     For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section
     Title macros.

   OpenBSD Macro
           Usage: .Ox [⟨version⟩] ...

                    .Ox 1.0  OpenBSD 1.0

   BSD/OS Macro
           Usage: .Bsx [⟨version⟩] ...

                    .Bsx 1.0  BSD/OS 1.0

   Unix Macro
           Usage: .Ux ...

                    .Ux  UNIX

   Emphasis Macro
     Text may be stressed or emphasized with the ‘.Em’ macro.  The usual font for emphasis is
     italic.

           Usage: .Em ⟨argument⟩ ...

                    .Em does not          does not
                    .Em exceed 1024 .     exceed 1024.
                    .Em vide infra ) ) ,  vide infra)),

     The default width is 10n.

   Font Mode
     The ‘.Bf’ font mode must be ended with the ‘.Ef’ macro (the latter takes no arguments).
     Font modes may be nested within other font modes.

     ‘.Bf’ has the following syntax:

           .Bf ⟨font mode⟩

     ⟨font mode⟩ must be one of the following three types:

           Em | -emphasis  Same as if the ‘.Em’ macro was used for the entire block of text.
           Li | -literal   Same as if the ‘.Li’ macro was used for the entire block of text.
           Sy | -symbolic  Same as if the ‘.Sy’ macro was used for the entire block of text.

     Both macros are neither callable nor parsed.

   Enclosure and Quoting Macros
     The concept of enclosure is similar to quoting.  The object being to enclose one or more
     strings between a pair of characters like quotes or parentheses.  The terms quoting and
     enclosure are used interchangeably throughout this document.  Most of the one-line enclosure
     macros end in small letter ‘q’ to give a hint of quoting, but there are a few
     irregularities.  For each enclosure macro, there is a pair of opening and closing macros
     that end with the lowercase letters ‘o’ and ‘c’ respectively.

     Quote   Open   Close   Function                  Result
     .Aq     .Ao    .Ac     Angle Bracket Enclosure   <string>

     .Bq     .Bo    .Bc     Bracket Enclosure         [string]
     .Brq    .Bro   .Brc    Brace Enclosure           {string}
     .Dq     .Do    .Dc     Double Quote              “string”
     .Eq     .Eo    .Ec     Enclose String (in XY)    XstringY
     .Pq     .Po    .Pc     Parenthesis Enclosure     (string)
     .Ql                    Quoted Literal            “string” or string
     .Qq     .Qo    .Qc     Straight Double Quote     "string"
     .Sq     .So    .Sc     Single Quote              ‘string’

     All macros ending with ‘q’ and ‘o’ have a default width value of 12n.

     .Eo, .Ec  These macros expect the first argument to be the opening and closing strings,
               respectively.

     .Es, .En  To work around the nine-argument limit in the original troff program, mdoc
               supports two other macros that are now obsolete.  ‘.Es’ uses its first and second
               parameters as opening and closing marks which are then used to enclose the
               arguments of ‘.En’.  The default width value is 12n for both macros.

     .Eq       The first and second arguments of this macro are the opening and closing strings
               respectively, followed by the arguments to be enclosed.

     .Ql       The quoted literal macro behaves differently in troff and nroff modes.  If
               formatted with nroff(1), a quoted literal is always quoted.  If formatted with
               troff, an item is only quoted if the width of the item is less than three
               constant-width characters.  This is to make short strings more visible where the
               font change to literal (constant-width) is less noticeable.

               The default width is 16n.

     .Pf       The prefix macro suppresses the whitespace between its first and second argument:

                     .Pf ( Fa name2  (name2

               The default width is 12n.

               The ‘.Ns’ macro (see below) performs the analogous suffix function.

     .Ap       The ‘.Ap’ macro inserts an apostrophe and exits any special text modes, continuing
               in ‘.No’ mode.

     Examples of quoting:

           .Aq                      ⟨⟩
           .Aq Pa ctype.h ) ,       ⟨ctype.h⟩),
           .Bq                      []
           .Bq Em Greek , French .  [Greek, French].
           .Dq                      “”
           .Dq string abc .         “string abc”.
           .Dq '\[ha][A-Z]'         “'^[A-Z]'”
           .Ql man mdoc             ‘man mdoc’
           .Qq                      ""
           .Qq string ) ,           "string"),
           .Qq string Ns ),         "string),"
           .Sq                      ‘’
           .Sq string               ‘string’
           .Em or Ap ing            or'ing

     For a good example of nested enclosure macros, see the ‘.Op’ option macro.  It was created
     from the same underlying enclosure macros as those presented in the list above.  The ‘.Xo’
     and ‘.Xc’ extended argument list macros are discussed below.

   Normal text macro
     ‘No’ formats subsequent argument(s) normally, ending the effect of ‘Em’ and similar.
     Parsing is not suppressed, so you must prefix words like ‘No’ with ‘\&’ to avoid their
     interpretation as mdoc macros.

           Usage: .No argument ...

                    .Em Use caution No here .  → Use caution here.
                    .Em No dogs allowed .      → No dogs allowed.
                    .Em \&No dogs allowed .    → No dogs allowed.

     The default width is 12n.

   No-Space Macro
     The ‘.Ns’ macro suppresses insertion of a space between the current position and its first
     parameter.  For example, it is useful for old style argument lists where there is no space
     between the flag and argument:

           Usage: ... ⟨argument⟩ Ns [⟨argument⟩] ...
                  .Ns ⟨argument⟩ ...

                    .Op Fl I Ns Ar directory  [-Idirectory]

     Note: The ‘.Ns’ macro always invokes the ‘.No’ macro after eliminating the space unless
     another macro name follows it.  If used as a command (i.e., the second form above in the
     ‘Usage’ line), ‘.Ns’ is identical to ‘.No’.

   (Sub)section cross references
     Use the ‘.Sx’ macro to cite a (sub)section heading within the given document.

           Usage: .Sx ⟨section-reference⟩ ...

                    .Sx Files  → Files

     The default width is 16n.

   Symbolics
     The symbolic emphasis macro is generally a boldface macro in either the symbolic sense or
     the traditional English usage.

           Usage: .Sy ⟨symbol⟩ ...

                    .Sy Important Notice  → Important Notice

     The default width is 6n.

   Mathematical Symbols
     Use this macro for mathematical symbols and similar things.

           Usage: .Ms ⟨math symbol⟩ ...

                    .Ms sigma  → sigma

     The default width is 6n.

   References and Citations
     The following macros make a modest attempt to handle references.  At best, the macros make
     it convenient to manually drop in a subset of refer(1) style references.

           .Rs     Reference start (does not take arguments).  In a section titled “See also”, it
                   causes a break and begins collection of reference information until the
                   reference end macro is read.
           .Re     Reference end (does not take arguments).  The reference is printed.
           .%A     Reference author name; one name per invocation.
           .%B     Book title.
           .%C     City/place.
           .%D     Date.
           .%I     Issuer/publisher name.
           .%J     Journal name.
           .%N     Issue number.
           .%O     Optional information.
           .%P     Page number.
           .%Q     Corporate or foreign author.
           .%R     Report name.
           .%T     Title of article.
           .%U     Optional hypertext reference.
           .%V     Volume.

     Macros beginning with ‘%’ are not callable but accept multiple arguments in the usual way.
     Only the ‘.Tn’ macro is handled properly as a parameter; other macros will cause strange
     output.  ‘.%B’ and ‘.%T’ can be used outside of the ‘.Rs/.Re’ environment.

     Example:

           .Rs
           .%A "Matthew Bar"
           .%A "John Foo"
           .%T "Implementation Notes on foobar(1)"
           .%R "Technical Report ABC-DE-12-345"
           .%Q "Drofnats College"
           .%C "Nowhere"
           .%D "April 1991"
           .Re

     produces

           Matthew Bar and John Foo, Implementation Notes on foobar(1), Technical Report ABC-
           DE-12-345, Drofnats College, Nowhere, April 1991.

   Trade Names or Acronyms
     The trade name macro prints its arguments at a smaller type size.  It is intended to imitate
     a small caps fonts for fully capitalized acronyms.

           Usage: .Tn ⟨symbol⟩ ...

                    .Tn DEC    DEC
                    .Tn ASCII  ASCII

     The default width is 10n.

   Extended Arguments
     The .Xo and .Xc macros allow one to extend an argument list on a macro boundary for the
     ‘.It’ macro (see below).  Note that .Xo and .Xc are implemented similarly to all other
     macros opening and closing an enclosure (without inserting characters, of course).  This
     means that the following is true for those macros also.

     Here is an example of ‘.Xo’ using the space mode macro to turn spacing off:

           .Bd -literal -offset indent
           .Sm off
           .It Xo Sy I Ar operation
           .No \en Ar count No \en
           .Xc
           .Sm on
           .Ed

     produces

           Ioperation\ncount\n

     Another one:

           .Bd -literal -offset indent
           .Sm off
           .It Cm S No / Ar old_pattern Xo
           .No / Ar new_pattern
           .No / Op Cm g
           .Xc
           .Sm on
           .Ed

     produces

           S/old_pattern/new_pattern/[g]

     Another example of ‘.Xo’ and enclosure macros: Test the value of a variable.

           .Bd -literal -offset indent
           .It Xo
           .Ic .ifndef
           .Oo \&! Oc Ns Ar variable Oo
           .Ar operator variable No ...
           .Oc Xc
           .Ed

     produces

           .ifndef [!]variable [operator variable ...]

Page structure domain

   Section headings
     The following ‘.Sh’ section heading macros are required in every man page.  The remaining
     section headings are recommended at the discretion of the author writing the manual page.
     The ‘.Sh’ macro is parsed but not generally callable.  It can be used as an argument in a
     call to ‘.Sh’ only; it then reactivates the default font for ‘.Sh’.

     The default width is 8n.

     .Sh Name           The ‘.Sh Name’ macro is mandatory.  If not specified, headers, footers,
                        and page layout defaults will not be set and things will be rather
                        unpleasant.  The Name section consists of at least three items.  The
                        first is the ‘.Nm’ name macro naming the subject of the man page.  The
                        second is the name description macro, ‘.Nd’, which separates the subject
                        name from the third item, which is the description.  The description
                        should be the most terse and lucid possible, as the space available is
                        small.

                        ‘.Nd’ first prints ‘-’, then all its arguments.

     .Sh Library        This section is for section two and three function calls.  It should
                        consist of a single ‘.Lb’ macro call; see Library Names.

     .Sh Synopsis       The Synopsis section describes the typical usage of the subject of a man
                        page.  The macros required are either ‘.Nm’, ‘.Cd’, or ‘.Fn’ (and
                        possibly ‘.Fo’, ‘.Fc’, ‘.Fd’, and ‘.Ft’).  The function name macro ‘.Fn’
                        is required for manual page sections 2 and 3; the command and general
                        name macro ‘.Nm’ is required for sections 1, 5, 6, 7, and 8.  Section 4
                        manuals require a ‘.Nm’, ‘.Fd’ or a ‘.Cd’ configuration device usage
                        macro.  Several other macros may be necessary to produce the synopsis
                        line as shown below:

                              cat [-benstuv] [-] file ...

                        The following macros were used:

                              .Nm cat
                              .Op Fl benstuv
                              .Op Fl
                              .Ar file No ...

     .Sh Description    In most cases the first text in the Description section is a brief
                        paragraph on the command, function or file, followed by a lexical list of
                        options and respective explanations.  To create such a list, the ‘.Bl’
                        (begin list), ‘.It’ (list item) and ‘.El’ (end list) macros are used (see
                        Lists and Columns below).

     .Sh Implementation notes
                        Implementation specific information should be placed here.

     .Sh Return values  Sections 2, 3 and 9 function return values should go here.  The ‘.Rv’
                        macro may be used to generate text for use in the Return values section
                        for most section 2 and 3 library functions; see Return Values.

     The following ‘.Sh’ section headings are part of the preferred manual page layout and must
     be used appropriately to maintain consistency.  They are listed in the order in which they
     would be used.

     .Sh Environment    The Environment section should reveal any related environment variables
                        and clues to their behavior and/or usage.

     .Sh Files          Files which are used or created by the man page subject should be listed
                        via the ‘.Pa’ macro in the Files section.

     .Sh Examples       There are several ways to create examples.  See subsection Examples and
                        Displays below for details.

     .Sh Diagnostics    Diagnostic messages from a command should be placed in this section.  The
                        ‘.Ex’ macro may be used to generate text for use in the Diagnostics
                        section for most section 1, 6 and 8 commands; see Exit Status.

     .Sh Compatibility  Known compatibility issues (e.g. deprecated options or parameters) should
                        be listed here.

     .Sh Errors         Specific error handling, especially from library functions (man page
                        sections 2, 3, and 9) should go here.  The ‘.Er’ macro is used to specify
                        an error (errno).

     .Sh See also       References to other material on the man page topic and cross references
                        to other relevant man pages should be placed in the See also section.
                        Cross references are specified using the ‘.Xr’ macro.  Currently refer(1)
                        style references are not accommodated.

                        It is recommended that the cross references be sorted by section number,
                        then alphabetically by name within each section, then separated by
                        commas.  Example:

                        ls(1), ps(1), group(5), passwd(5)

     .Sh Standards      If the command, library function, or file adheres to a specific
                        implementation such as IEEE Std 1003.2 (“POSIX.2”) or ANSI X3.159-1989
                        (“ANSI C89”) this should be noted here.  If the command does not adhere
                        to any standard, its history should be noted in the History section.

     .Sh History        Any command which does not adhere to any specific standards should be
                        outlined historically in this section.

     .Sh Authors        Credits should be placed here.  Use the ‘.An’ macro for names and the
                        ‘.Aq’ macro for email addresses within optional contact information.
                        Explicitly indicate whether the person authored the initial manual page
                        or the software or whatever the person is being credited for.

     .Sh Bugs           Blatant problems with the topic go here.

     User-specified ‘.Sh’ sections may be added; for example, this section was set with:

                    .Sh "Page structure domain"

   Subsection headings
     Subsection headings have exactly the same syntax as section headings: ‘.Ss’ is parsed but
     not generally callable.  It can be used as an argument in a call to ‘.Ss’ only; it then
     reactivates the default font for ‘.Ss’.

     The default width is 8n.

   Paragraphs and Line Spacing
     .Pp  The ‘.Pp’ paragraph command may be used to specify a line space where necessary.  The
          macro is not necessary after a ‘.Sh’ or ‘.Ss’ macro or before a ‘.Bl’ or ‘.Bd’ macro
          (which both assert a vertical distance unless the -compact flag is given).

          The macro is neither callable nor parsed and takes no arguments; an alternative name is
          ‘.Lp’.

   Keeps
     The only keep that is implemented at this time is for words.  The macros are ‘.Bk’ (begin
     keep) and ‘.Ek’ (end keep).  The only option that ‘.Bk’ currently accepts is -words (also
     the default); this prevents breaks in the middle of options.  In the example for make
     command-line arguments (see What's in a Name), the keep prevents nroff from placing the flag
     and the argument on separate lines.

     Neither macro is callable or parsed.

     More work needs to be done on the keep macros; specifically, a -line option should be added.

   Examples and Displays
     There are seven types of displays.

     .D1  (This is D-one.)  Display one line of indented text.  This macro is parsed but not
          callable.

                -ldghfstru

          The above was produced by: .D1 Fl ldghfstru.

     .Dl  (This is D-ell.)  Display one line of indented literal text.  The ‘.Dl’ example macro
          has been used throughout this file.  It allows the indentation (display) of one line of
          text.  Its default font is set to constant width (literal).  ‘.Dl’ is parsed but not
          callable.

                % ls -ldg /usr/local/bin

          The above was produced by: .Dl % ls \-ldg /usr/local/bin.

     .Bd  Begin display.  The ‘.Bd’ display must be ended with the ‘.Ed’ macro.  It has the
          following syntax:

                .Bd {-literal | -filled | -unfilled | -ragged | -centered} [-offset ⟨string⟩]
                     [-file ⟨file name⟩] [-compact]

          -ragged            Fill, but do not adjust the right margin (only left-justify).
          -centered          Center lines between the current left and right margin.  Note that
                             each single line is centered.
          -unfilled          Do not fill; break lines where their input lines are broken.  This
                             can produce overlong lines without warning messages.
          -filled            Display a filled block.  The block of text is formatted (i.e., the
                             text is justified on both the left and right side).
          -literal           Display block with literal font (usually fixed-width).  Useful for
                             source code or simple tabbed or spaced text.
          -filefile name⟩  The file whose name follows the -file flag is read and displayed
                             before any data enclosed with ‘.Bd’ and ‘.Ed’, using the selected
                             display type.  Any troff/mdoc commands in the file will be
                             processed.
          -offsetstring⟩   If -offset is specified with one of the following strings, the
                             string is interpreted to indicate the level of indentation for the
                             forthcoming block of text:

                             left        Align block on the current left margin; this is the
                                         default mode of ‘.Bd’.
                             center      Supposedly center the block.  At this time
                                         unfortunately, the block merely gets left aligned about
                                         an imaginary center margin.
                             indent      Indent by one default indent value or tab.  The default
                                         indent value is also used for the ‘.D1’ and ‘.Dl’
                                         macros, so one is guaranteed the two types of displays
                                         will line up.  The indentation value is normally set
                                         to 6n or about two thirds of an inch (six constant width
                                         characters).
                             indent-two  Indent two times the default indent value.
                             right       This left aligns the block about two inches from the
                                         right side of the page.  This macro needs work and
                                         perhaps may never do the right thing within troff.

                             If ⟨string⟩ is a valid numeric expression instead (with a scaling
                             indicator other thanu’), use that value for indentation.  The most
                             useful scaling indicators are ‘m’ and ‘n’, specifying the so-called
                             Em and En square.  This is approximately the width of the letters
                             ‘m’ and ‘n’ respectively of the current font (for nroff output, both
                             scaling indicators give the same values).  If ⟨string⟩ isn't a
                             numeric expression, it is tested whether it is an mdoc macro name,
                             and the default offset value associated with this macro is used.
                             Finally, if all tests fail, the width of ⟨string⟩ (typeset with a
                             fixed-width font) is taken as the offset.
          -compact           Suppress insertion of vertical space before begin of display.

     .Ed  End display (takes no arguments).

   Lists and Columns
     There are several types of lists which may be initiated with the ‘.Bl’ begin-list macro.
     Items within the list are specified with the ‘.It’ item macro, and each list must end with
     the ‘.El’ macro.  Lists may be nested within themselves and within displays.  The use of
     columns inside of lists or lists inside of columns is untested.

     In addition, several list attributes may be specified such as the width of a tag, the list
     offset, and compactness (blank lines between items allowed or disallowed).  Most of this
     document has been formatted with a tag style list (-tag).

     It has the following syntax forms:

           .Bl {-hang | -ohang | -tag | -diag | -inset} [-width ⟨string⟩] [-offset ⟨string⟩]
                [-compact]
           .Bl -column [-offset ⟨string⟩] ⟨string1⟩ ⟨string2⟩ ...
           .Bl {-item | -enum [-nested] | -bullet | -hyphen | -dash} [-offset ⟨string⟩]
                [-compact]

     And now a detailed description of the list types.

     -bullet  A bullet list.

                    .Bl -bullet -offset indent -compact
                    .It
                    Bullet one goes here.
                    .It
                    Bullet two here.
                    .El

              Produces:

                       Bullet one goes here.
                       Bullet two here.

     -dash (or -hyphen)
              A dash list.

                    .Bl -dash -offset indent -compact
                    .It
                    Dash one goes here.
                    .It
                    Dash two here.
                    .El

              Produces:

                    -   Dash one goes here.
                    -   Dash two here.

     -enum    An enumerated list.

                    .Bl -enum -offset indent -compact
                    .It
                    Item one goes here.
                    .It
                    And item two here.
                    .El

              The result:

                    1.   Item one goes here.
                    2.   And item two here.

              If you want to nest enumerated lists, use the -nested flag (starting with the
              second-level list):

                    .Bl -enum -offset indent -compact
                    .It
                    Item one goes here
                    .Bl -enum -nested -compact
                    .It
                    Item two goes here.
                    .It
                    And item three here.
                    .El
                    .It
                    And item four here.
                    .El

              Result:

                    1.   Item one goes here.
                         1.1.   Item two goes here.
                         1.2.   And item three here.
                    2.   And item four here.

     -item    A list of type -item without list markers.

                    .Bl -item -offset indent
                    .It
                    Item one goes here.
                    Item one goes here.
                    Item one goes here.
                    .It
                    Item two here.
                    Item two here.
                    Item two here.
                    .El

              Produces:

                    Item one goes here.  Item one goes here.  Item one goes here.

                    Item two here.  Item two here.  Item two here.

     -tag     A list with tags.  Use -width to specify the tag width.

                    SL    sleep time of the process (seconds blocked)
                    PAGEIN
                          number of disk I/O operations resulting from references by the process
                          to pages not loaded in core.
                    UID   numerical user-id of process owner
                    PPID  numerical id of parent of process priority (non-positive when in non-
                          interruptible wait)

              The raw text:

                    .Bl -tag -width "PPID" -compact -offset indent
                    .It SL
                    sleep time of the process (seconds blocked)
                    .It PAGEIN
                    number of disk I/O operations resulting from references
                    by the process to pages not loaded in core.
                    .It UID
                    numerical user-id of process owner
                    .It PPID
                    numerical id of parent of process priority
                    (non-positive when in non-interruptible wait)
                    .El

     -diag    Diag lists create section four diagnostic lists and are similar to inset lists
              except callable macros are ignored.  The -width flag is not meaningful in this
              context.

              Example:

                    .Bl -diag
                    .It You can't use Sy here.
                    The message says all.
                    .El

              produces

              You can't use Sy here.  The message says all.

     -hang    A list with hanging tags.

                    Hanged  labels appear similar to tagged lists when the label is smaller than
                            the label width.

                    Longer hanged list labels blend into the paragraph unlike tagged paragraph
                            labels.

              And the unformatted text which created it:

                    .Bl -hang -offset indent
                    .It Em Hanged
                    labels appear similar to tagged lists when the
                    label is smaller than the label width.
                    .It Em Longer hanged list labels
                    blend into the paragraph unlike
                    tagged paragraph labels.
                    .El

     -ohang   Lists with overhanging tags do not use indentation for the items; tags are written
              to a separate line.

                    SL
                    sleep time of the process (seconds blocked)

                    PAGEIN
                    number of disk I/O operations resulting from references by the process to
                    pages not loaded in core.

                    UID
                    numerical user-id of process owner

                    PPID
                    numerical id of parent of process priority (non-positive when in non-
                    interruptible wait)

              The raw text:

                    .Bl -ohang -offset indent
                    .It Sy SL
                    sleep time of the process (seconds blocked)
                    .It Sy PAGEIN
                    number of disk I/O operations resulting from references
                    by the process to pages not loaded in core.
                    .It Sy UID
                    numerical user-id of process owner
                    .It Sy PPID
                    numerical id of parent of process priority
                    (non-positive when in non-interruptible wait)
                    .El

     -inset   Here is an example of inset labels:

                    Tag The tagged list (also called a tagged paragraph) is the most common type
                    of list used in the Berkeley manuals.  Use a -width attribute as described
                    below.

                    Diag Diag lists create section four diagnostic lists and are similar to inset
                    lists except callable macros are ignored.

                    Hang Hanged labels are a matter of taste.

                    Ohang Overhanging labels are nice when space is constrained.

                    Inset Inset labels are useful for controlling blocks of paragraphs and are
                    valuable for converting mdoc manuals to other formats.

              Here is the source text which produced the above example:

                    .Bl -inset -offset indent
                    .It Em Tag
                    The tagged list (also called a tagged paragraph)
                    is the most common type of list used in the
                    Berkeley manuals.
                    .It Em Diag
                    Diag lists create section four diagnostic lists
                    and are similar to inset lists except callable
                    macros are ignored.
                    .It Em Hang
                    Hanged labels are a matter of taste.
                    .It Em Ohang
                    Overhanging labels are nice when space is constrained.
                    .It Em Inset
                    Inset labels are useful for controlling blocks of
                    paragraphs and are valuable for converting
                    .Xr mdoc
                    manuals to other formats.
                    .El

     -column  This list type generates multiple columns.  The number of columns and the width of
              each column is determined by the arguments to the -column list, ⟨string1⟩,
              ⟨string2⟩, etc.  If ⟨stringN⟩ starts with a ‘.’ (dot) immediately followed by a
              valid mdoc macro name, interpret ⟨stringN⟩ and use the width of the result.
              Otherwise, the width of ⟨stringN⟩ (typeset with a fixed-width font) is taken as the
              Nth column width.

              Each ‘.It’ argument is parsed to make a row, each column within the row is a
              separate argument separated by a tab or the ‘.Ta’ macro.

              The table:

                    String    Nroff    Troff
                    <=        <=       ≤
                    >=        >=       ≥

              was produced by:

              .Bl -column -offset indent ".Sy String" ".Sy Nroff" ".Sy Troff"
              .It Sy String Ta Sy Nroff Ta Sy Troff
              .It Li <= Ta <= Ta \*(<=
              .It Li >= Ta >= Ta \*(>=
              .El

              Don't abuse this list type!  For more complicated cases it might be far better and
              easier to use tbl(1), the table preprocessor.

     Other keywords:

     -widthstring⟩   If ⟨string⟩ starts with a ‘.’ (dot) immediately followed by a valid mdoc
                       macro name, interpret ⟨string⟩ and use the width of the result.  Almost
                       all lists in this document use this option.

                       Example:

                             .Bl -tag -width ".Fl test Ao Ar string Ac"
                             .It Fl test Ao Ar string Ac
                             This is a longer sentence to show how the
                             .Fl width
                             flag works in combination with a tag list.
                             .El

                       gives:

                       -teststring⟩  This is a longer sentence to show how the -width flag
                                       works in combination with a tag list.

                       (Note that the current state of mdoc is saved before ⟨string⟩ is
                       interpreted; afterwards, all variables are restored again.  However, boxes
                       (used for enclosures) can't be saved in GNU troff(1); as a consequence,
                       arguments must always be balanced to avoid nasty errors.  For example, do
                       not write ‘.Ao Ar string’ but ‘.Ao Ar string Xc’ instead if you really
                       need only an opening angle bracket.)

                       Otherwise, if ⟨string⟩ is a valid numeric expression (with a scaling
                       indicator other thanu’), use that value for indentation.  The most
                       useful scaling indicators are ‘m’ and ‘n’, specifying the so-called Em and
                       En square.  This is approximately the width of the letters ‘m’ and ‘n’
                       respectively of the current font (for nroff output, both scaling
                       indicators give the same values).  If ⟨string⟩ isn't a numeric expression,
                       it is tested whether it is an mdoc macro name, and the default width value
                       associated with this macro is used.  Finally, if all tests fail, the width
                       of ⟨string⟩ (typeset with a fixed-width font) is taken as the width.

                       If a width is not specified for the tag list type, ‘6n’ is used.

     -offsetstring⟩  If ⟨string⟩ is indent, a default indent value (normally set to 6n, similar
                       to the value used in ‘.Dl’ or ‘.Bd’) is used.  If ⟨string⟩ is a valid
                       numeric expression instead (with a scaling indicator other thanu’), use
                       that value for indentation.  The most useful scaling indicators are ‘m’
                       and ‘n’, specifying the so-called Em and En square.  This is approximately
                       the width of the letters ‘m’ and ‘n’ respectively of the current font (for
                       nroff output, both scaling indicators give the same values).  If ⟨string⟩
                       isn't a numeric expression, it is tested whether it is an mdoc macro name,
                       and the default offset value associated with this macro is used.  Finally,
                       if all tests fail, the width of ⟨string⟩ (typeset with a fixed-width font)
                       is taken as the offset.

     -compact          Suppress insertion of vertical space before the list and between list
                       items.

Miscellaneous macros

     A double handful of macros fit only uncomfortably into one of the above sections.  Of these,
     we couldn't find attested examples for ‘Me’ or ‘Ot’.  They are documented here for
     completeness—if you know their proper usage, please send a mail to groff@gnu.org and include
     a specimen with its provenance.

     .Bt  formats boilerplate text.

                .Bt  → is currently in beta test.

          It is neither callable nor parsed and takes no arguments.  Its default width is 6n.

     .Fr  is an obsolete means of specifying a function return value.

                Usage: .Fr return-value ...

          ‘Fr’ allows a break right before the return value (usually a single digit) which is bad
          typographical behaviour.  Instead, set the return value with the rest of the code,
          using ‘\~’ to tie the return value to the previous word.

          Its default width is 12n.

     .Hf  Inlines the contents of a (header) file into the document.

                Usage: .Hf file

          It first prints ‘File:’ followed by the file name, then the contents of file.  It is
          neither callable nor parsed.

     .Lk  Embed hyperlink.

                Usage: .Lk uri [link-text]

          Its default width is 6n.

     .Me  Usage unknown.  The mdoc sources describe it as a macro for “menu entries”.

          Its default width is 6n.

     .Mt  Embed email address.

                Usage: .Mt email-address

          Its default width is 6n.

     .Ot  Usage unknown.  The mdoc sources describe it as “old function type (fortran)”.

     .Sm  Manipulate or toggle argument-spacing mode.

                Usage: .Sm [on | off] ...

          If argument-spacing mode is off, no spaces between macro arguments are inserted.  If
          called without a parameter (or if the next parameter is neither ‘on’ nor ‘off’), ‘Sm’
          toggles argument-spacing mode.

          Its default width is 8n.

     .Ud  formats boilerplate text.

                .Ud  → currently under development.

          It is neither callable nor parsed and takes no arguments.  Its default width is 8n.

Predefined strings

     The following strings are predefined for compatibility with legacy mdoc documents.
     Contemporary ones should use the alternatives shown in the “Prefer” column below.  See
     groff_char(7) for a full discussion of these special character escape sequences.

     String   7-bit     8-bit     UCS   Prefer   Meaning
     \*(<=    <=        <=        ≤     \(<=     less than or equal to
     \*(>=    >=        >=        ≥     \(>=     greater than or equal to
     \*(Rq    "         "         ”     \(rq     right double quote
     \*(Lq    "         "         “     \(lq     left double quote
     \*(ua    ^         ^         ↑     \(ua     vertical arrow up
     \*(aa    '         ´         ´     \(aa     acute accent
     \*(ga    `         `         `     \(ga     grave accent
     \*(q     "         "         "     \(dq     neutral double quote
     \*(Pi    pi        pi        π     \(*p     lowercase pi
     \*(Ne    !=        !=        ≠     \(!=     not equals
     \*(Le    <=        <=        ≤     \(<=     less than or equal to
     \*(Ge    >=        >=        ≥     \(>=     greater than or equal to
     \*(Lt    <         <         <     <        less than
     \*(Gt    >         >         >     >        greater than
     \*(Pm    +-        ±         ±     \(+-     plus or minus
     \*(If    infinity  infinity  ∞     \(if     infinity
     \*(Am    &         &         &     &        ampersand
     \*(Na    NaN       NaN       NaN   NaN      not a number
     \*(Ba    |         |         |     |        bar

     Some column headings are shorthand for standardized character encodings; “7-bit” for ISO
     646:1991 IRV (US-ASCII), “8-bit” for ISO 8859-1 (Latin-1) and IBM code page 1047, and “UCS”
     for ISO 10646 (Unicode character set).  Historically, mdoc configured the string definitions
     to fit the capabilities expected of the output device.  Old typesetters lacked directional
     double quotes, producing repeated directional single quotes ‘‘like this’’; early versions of
     mdoc in fact defined the ‘Lq’ and ‘Rq’ strings this way.  Nowadays, output drivers take on
     the responsibility of glyph substitution, as they possess relevant knowledge of their
     available repertoires.

Diagnostics

     The debugging macro ‘.Db’ offered by previous versions of mdoc is unavailable in GNU
     troff(1) since the latter provides better facilities to check parameters; additionally,
     groff mdoc implements many error and warning messages, making the package more robust and
     more verbose.

     The remaining debugging macro is ‘.Rd’, which dumps the package's global register and string
     contents to the standard error stream.  A normal user will never need it.

Options

     The following groff options set registers (with -r) and strings (with -d) recognized and
     used by the mdoc macro package.  To ensure rendering consistent with output device
     capabilities and reader preferences, man pages should never manipulate them.

     Setting string ‘AD’ configures the adjustment mode for most formatted text.  Typical values
     are ‘b’ for adjustment to both margins (the default), or ‘l’ for left alignment (ragged
     right margin).  Any valid argument to groff's ‘ad’ request may be used.  See groff(7) for
     less-common choices.
           groff -Tutf8 -dAD=l -mdoc groff_mdoc.7 | less -R

     Setting register ‘C’ to 1 numbers output pages consecutively, rather than resetting the page
     number to 1 (or the value of register ‘P’) with each new mdoc document.

     By default, the package inhibits page breaks, headers, and footers in the midst of the
     document text if it is being displayed with a terminal device such as ‘latin1’ or ‘utf8’, to
     enable more efficient viewing of the page.  This behavior can be changed to format the page
     as if for 66-line Teletype output by setting the continuous rendering register ‘cR’ to zero
     while calling groff(1).
           groff -Tlatin1 -rcR=0 -mdoc foo.man > foo.txt
     On HTML devices, it cannot be disabled.

     Section headings (defined with ‘.Sh’) and page titles in headers (defined with ‘.Dt’) can be
     presented in full capitals by setting the registers ‘CS’ and ‘CT’, respectively, to 1.
     These transformations are off by default because they discard case distinction information.

     Setting register ‘D’ to 1 enables double-sided page layout, which is only distinct when not
     continuously rendering.  It places the page number at the bottom right on odd-numbered
     (recto) pages, and at the bottom left on even-numbered (verso) pages, swapping places with
     the arguments to ‘.Os’.
           groff -Tps -rD1 -mdoc foo.man > foo.ps

     The value of the ‘FT’ register determines the footer's distance from the page bottom; this
     amount is always negative and should specify a scaling unit.  At one half-inch above this
     location, the page text is broken before writing the footer.  It is ignored if continuous
     rendering is enabled.  The default is -0.5i.

     The ‘HF’ string sets the font used for section and subsection headings; the default is ‘B’
     (bold style of the default family).  Any valid argument to groff's ‘ft’ request may be used.

     Normally, automatic hyphenation is enabled using a mode appropriate to the groff locale; see
     section “Localization“ of groff(7).  It can be disabled by setting the ‘HY’ register to
     zero.
           groff -Tutf8 -rHY=0 -mdoc foo.man | less -R

     The paragraph and subsection heading indentation amounts can be changed by setting the
     registers ‘IN’ and ‘SN’.
           groff -Tutf8 -rIN=5n -rSN=2n -mdoc foo.man | less -R
     The default paragraph indentation is 7.2n on typesetters and 7n on terminals.  The default
     subsection heading indentation amount is 3n; section headings are set with an indentation of
     zero.

     The line and title lengths can be changed by setting the registers ‘LL’ and ‘LT’,
     respectively:
           groff -Tutf8 -rLL=100n -rLT=100n -mdoc foo.man | less -R
     If not set, both registers default to 78n for terminal devices and 6.5i otherwise.

     Setting the ‘P’ register starts enumeration of pages at its value.  The default is 1.

     To change the document font size to 11p or 12p, set register ‘S’ accordingly:
           groff -Tdvi -rS11 -mdoc foo.man > foo.dvi
     Register ‘S’ is ignored when formatting for terminal devices.

     Setting the ‘X’ register to a page number p numbers its successors as pa, pb, pc, and so
     forth.  The register tracking the suffixed page letter uses format ‘a’ (see the ‘af’ request
     in groff(7)).

Files

     /usr/share/groff/1.23.0/tmac/andoc.tmac
             This brief groff program detects whether the man or mdoc macro package is being used
             by a document and loads the correct macro definitions, taking advantage of the fact
             that pages using them must call TH or Dd, respectively, before any other macros.  A
             user typing, for example,
                   groff -mandoc page.1
             need not know which package the file page.1 uses.  Multiple man pages, in either
             format, can be handled; andoc.tmac reloads each macro package as necessary.

     /usr/share/groff/1.23.0/tmac/doc.tmac
             implements the bulk of the groff mdoc package and loads further components as needed
             from the mdoc subdirectory.

     /usr/share/groff/1.23.0/tmac/mdoc.tmac
             is a wrapper that loads doc.tmac.

     /usr/share/groff/1.23.0/tmac/mdoc/doc-common
             defines macros, registers, and strings concerned with the production of formatted
             output.  It includes strings of the form ‘doc-volume-ds-X’ and ‘doc-volume-as-X’ for
             manual section titles and architecture identifiers, respectively, where X is an
             argument recognized by .Dt.

     /usr/share/groff/1.23.0/tmac/mdoc/doc-nroff
             defines parameters appropriate for rendering to terminal devices.

     /usr/share/groff/1.23.0/tmac/mdoc/doc-ditroff
             defines parameters appropriate for rendering to typesetter devices.

     /usr/share/groff/1.23.0/tmac/mdoc/doc-syms
             defines many strings and macros that interpolate formatted text, such as names of
             operating system releases, *BSD libraries, and standards documents.  The string
             names are of the form ‘doc-str-O-V’, ‘doc-str-St--S-I’ (observe the double dashes),
             or ‘doc-str-Lb-L’, where O is one of the operating system macros from section
             General text domain above, V is an encoding of an operating system release
             (sometimes omitted along with the ‘-’ preceding it), S an identifier for a standards
             body or committee, I one for an issue of a standard promulgated by S, and L a
             keyword identifying a *BSD library.

     /usr/share/groff/site-tmac/mdoc.local
             This file houses local additions and customizations to the package.  It can be
             empty.

See also

     The mandoc: https://mandoc.bsd.lv/ project maintains an independent implementation of the
     mdoc language and a renderer that directly parses its markup as well as that of man.

     groff(1), man(1), troff(1), groff_man(7), mdoc(7)

Bugs

     Section 3f has not been added to the header routines.

     ‘.Fn’ needs to have a check to prevent splitting up the line if its length is too short.
     Occasionally it separates the last parenthesis, and sometimes looks ridiculous if output
     lines are being filled.

     The list and display macros do not do any keeps and certainly should be able to.

     As of groff 1.23, ‘Tn’ no longer changes the type size; this functionality may return in the
     next release.