GROFF_MDOC(7)       NetBSD Miscellaneous Information Manual      GROFF_MDOC(7)

NAME
     groff_mdoc -- reference for groff's mdoc implementation

SYNOPSIS
     groff -mdoc file ...

DESCRIPTION
     A complete reference for writing UNIX manual pages with the -mdoc macro
     package; a content-based and domain-based formatting package for GNU
     troff(1).  Its predecessor, the -man(7) package, addressed page layout
     leaving the manipulation of fonts and other typesetting details to the
     individual author.  In -mdoc, page layout macros make up the page
     structure domain which consists of macros for titles, section headers,
     displays and lists - essentially items which affect the physical position
     of text on a formatted page.  In addition to the page structure domain,
     there are two more domains, the manual domain and the general text
     domain.  The general text domain is defined as macros which perform tasks
     such as quoting or emphasizing pieces of text.  The manual domain is
     defined as macros that are a subset of the day to day informal language
     used to describe commands, routines and related UNIX files.  Macros in
     the manual domain handle command names, command line arguments and
     options, function names, function parameters, pathnames, variables, cross
     references to other manual pages, and so on.  These domain items have
     value for both the author and the future user of the manual page.  Hope-
     fully, the consistency gained across the manual set will provide easier
     translation to future documentation tools.

     Throughout the UNIX manual pages, a manual entry is simply referred to as
     a man page, regardless of actual length and without sexist intention.

GETTING STARTED
     The material presented in the remainder of this document is outlined as
     follows:

           1.   TROFF IDIOSYNCRASIES
                Macro Usage
                Passing Space Characters in an Argument
                Trailing Blank Space Characters
                Escaping Special Characters
                Other Possible Pitfalls

           2.   A MANUAL PAGE TEMPLATE

           3.   CONVENTIONS

           4.   TITLE MACROS

           5.   INTRODUCTION OF MANUAL AND GENERAL TEXT DOMAINS
                What's in a Name...
                General Syntax

           6.   MANUAL DOMAIN
                Addresses
                Author Name
                Arguments
                Configuration Declarations (Section Four Only)
                Command Modifiers
                Defined Variables
                Errno's
                Environment Variables
                Flags
                Function Declarations
                Function Types
                Functions (Library Routines)
                Function Arguments
                Return Values
                Exit Status
                Interactive Commands
                Library Names
                Literals
                Names
                Options
                Pathnames
                Standards
                Variable Types
                Variables
                Manual Page Cross References

           7.   GENERAL TEXT DOMAIN
                AT&T Macro
                BSD Macro
                NetBSD Macro
                FreeBSD Macro
                OpenBSD Macro
                BSD/OS Macro
                UNIX Macro
                Emphasis Macro
                Font Mode
                Enclosure and Quoting Macros
                No-Op or Normal Text Macro
                No-Space Macro
                Section Cross References
                Symbolics
                Mathematical Symbols
                References and Citations
                Trade Names (or Acronyms and Type Names)
                Extended Arguments

           8.   PAGE STRUCTURE DOMAIN
                Section Headers
                Subsection Headers
                Paragraphs and Line Spacing
                Keeps
                Examples and Displays
                Lists and Columns

           9.   MISCELLANEOUS MACROS

           10.  PREDEFINED STRINGS

           11.  DIAGNOSTICS

           12.  FORMATTING WITH GROFF, TROFF, AND NROFF

           13.  FILES

           14.  SEE ALSO

           15.  BUGS

TROFF IDIOSYNCRASIES
     The -mdoc package attempts to simplify the process of writing a man page.
     Theoretically, one should not have to learn the tricky details of GNU
     troff(1) to use -mdoc; however, there are a few limitations which are
     unavoidable and best gotten out of the way.  And, too, be forewarned,
     this package is not fast.

   Macro Usage
     As in GNU troff(1), a macro is called by placing a `.' (dot character) at
     the beginning of a line followed by the two-character (or three-charac-
     ter) name for the macro.  There can be space or tab characters between
     the dot and the macro name.  Arguments may follow the macro separated by
     spaces (but no tabs).  It is the dot character at the beginning of the
     line which causes GNU troff(1) to interpret the next two (or more) char-
     acters as a macro name.  A single starting dot followed by nothing is
     ignored.  To place a `.' (dot character) at the beginning of an input
     line in some context other than a macro invocation, precede the `.' (dot)
     with the `\&' escape sequence which translates literally to a zero-width
     space, and is never displayed in the output.

     In general, GNU troff(1) macros accept an unlimited number of arguments
     (contrary to other versions of troff which can't handle more than nine
     arguments).  In limited cases, arguments may be continued or extended on
     the next line (See Extended Arguments below).  Almost all macros handle
     quoted arguments (see Passing Space Characters in an Argument below).

     Most of the -mdoc general text domain and manual domain macros are spe-
     cial in that their argument lists are parsed for callable macro names.
     This means an argument on the argument list which matches a general text
     or manual domain macro name (and which is defined to be callable) will be
     executed or called when it is processed.  In this case the argument,
     although the name of a macro, is not preceded by a `.' (dot).  This makes
     it possible to nest macros; for example the option macro, `.Op', may call
     the flag and argument macros, `Fl' and `Ar', to specify an optional flag
     with an argument:

           [-s bytes]  is produced by `.Op Fl s Ar bytes'

     To prevent a string from being interpreted as a macro name, precede the
     string with the escape sequence `\&':

           [Fl s Ar bytes]  is produced by `.Op \&Fl s \&Ar bytes'

     Here the strings `Fl' and `Ar' are not interpreted as macros.  Macros
     whose argument lists are parsed for callable arguments are referred to as
     parsed and macros which may be called from an argument list are referred
     to as callable throughout this document.  This is a technical faux pas as
     almost all of the macros in -mdoc are parsed, but as it was cumbersome to
     constantly refer to macros as being callable and being able to call other
     macros, the term parsed has been used.

     In the following, we call an -mdoc macro which starts a line (with a
     leading dot) a command if this distinction is necessary.

   Passing Space Characters in an Argument
     Sometimes it is desirable to give as an argument a string containing one
     or more blank space characters, say, to specify arguments to commands
     which expect particular arrangement of items in the argument list.  Addi-
     tionally, it makes -mdoc working faster.  For example, the function com-
     mand `.Fn' expects the first argument to be the name of a function and
     any remaining arguments to be function parameters.  As ANSI C stipulates
     the declaration of function parameters in the parenthesized parameter
     list, each parameter is guaranteed to be at minimum a two word string.
     For example, int foo.

     There are two possible ways to pass an argument which contains an embed-
     ded space.  One way of passing a string containing blank spaces is to use
     the hard or unpaddable space character `\ ', that is, a blank space pre-
     ceded by the escape character `\'.  This method may be used with any
     macro but has the side effect of interfering with the adjustment of text
     over the length of a line.  Troff sees the hard space as if it were any
     other printable character and cannot split the string into blank or new-
     line separated pieces as one would expect.  This method is useful for
     strings which are not expected to overlap a line boundary.  An alterna-
     tive is to use `\~', a paddable (i.e. stretchable), unbreakable space
     (this is a GNU troff(1) extension).  The second method is to enclose the
     string with double quotes.

     For example:

           fetch(char *str)  is created by `.Fn fetch char\ *str'

           fetch(char *str)  can also be created by `.Fn fetch "char *str"'

     If the `\' before the space in the first example or double quotes in the
     second example were omitted, `.Fn' would see three arguments, and the
     result would be:

           fetch(char, *str)

   Trailing Blank Space Characters
     Troff can be confused by blank space characters at the end of a line.  It
     is a wise preventive measure to globally remove all blank spaces from
     <blank-space><end-of-line> character sequences.  Should the need arise to
     use a blank character at the end of a line, it may be forced with an
     unpaddable space and the `\&' escape character.  For example,
     `string\ \&'.

   Escaping Special Characters
     Special characters like the newline character `\n' are handled by replac-
     ing the `\' with `\e' (e.g. `\en') to preserve the backslash.

   Other Possible Pitfalls
     A warning is emitted when an empty input line is found outside of dis-
     plays (see below).  Use `.sp' instead.  (Well, it is even better to use
     -mdoc macros to avoid the usage of low-level commands.)

     Leading spaces will cause a break and are output directly.  Avoid this
     behaviour if possible.  Similarly, do not use more than one space charac-
     ter between words in an ordinary text line; contrary to other text for-
     matters, they are not replaced with a single space.

     You can't pass `"' directly as an argument.  Use `\*[q]' (or `\*q')
     instead.

     By default, troff(1) inserts two space characters after a punctuation
     mark closing a sentence; characters like `)' or `'' are treated transpar-
     ently, not influencing the sentence-ending behaviour.  To change this,
     insert `\&' before or after the dot:

           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 can be seen in the first and third line, -mdoc handles punctuation
     characters specially in macro arguments.  This will be explained in sec-
     tion General Syntax below.  In the same way, you have to protect trailing
     full stops of abbreviations with a trailing zero-width space: `e.g.\&'.

     A comment in the source file of a man page can be either started with
     `.\"' on a single line, `\"' after some input, or `\#' anywhere (the lat-
     ter is a GNU troff(1) extension); the rest of such a line is ignored.

A MANUAL PAGE TEMPLATE
     The body of a man page is easily constructed from a basic template:

           .\" The following commands are required for all man pages.
           .Dd Month day, year
           .Os [OPERATING_SYSTEM] [version/release]
           .Dt DOCUMENT_TITLE [section number] [architecture/volume]
           .Sh NAME
           .Nm name
           .Nd one line description of name
           .\" This next command is for sections 2 and 3 only.
           .\" .Sh LIBRARY
           .Sh SYNOPSIS
           .Sh DESCRIPTION
           .\" The following commands should be uncommented and
           .\" used where appropriate.
           .\" .Sh IMPLEMENTATION NOTES
           .\" This next command is for sections 2, 3 and 9 function
           .\" return values only.
           .\" .Sh RETURN VALUES
           .\" This next command is for sections 1, 6, 7 and 8 only.
           .\" .Sh ENVIRONMENT
           .\" .Sh FILES
           .\" .Sh EXAMPLES
           .\" This next command is for sections 1, 6, 7, 8 and 9 only
           .\"     (command return values (to shell) and
           .\"     fprintf/stderr type diagnostics).
           .\" .Sh DIAGNOSTICS
           .\" .Sh COMPATIBILITY
           .\" This next command is for sections 2, 3 and 9 error
           .\"     and signal handling only.
           .\" .Sh ERRORS
           .\" .Sh SEE ALSO
           .\" .Sh STANDARDS
           .\" .Sh HISTORY
           .\" .Sh AUTHORS
           .\" .Sh BUGS

     The first items in the template are the commands `.Dd', `.Os', and `.Dt';
     the document date, the operating system the man page or subject source is
     developed or modified for, and the man page title (in upper case) along
     with the section of the manual the page belongs in.  These commands iden-
     tify the page and are discussed below in TITLE MACROS.

     The remaining items in the template are section headers (.Sh); of which
     NAME, SYNOPSIS, and DESCRIPTION are mandatory.  The headers are discussed
     in PAGE STRUCTURE DOMAIN, after presentation of MANUAL DOMAIN.  Several
     content macros are used to demonstrate page layout macros; reading about
     content macros before page layout macros is recommended.

CONVENTIONS
     In the description of all macros below, optional arguments are put into
     brackets.  An ellipsis (`...') represents zero or more additional argu-
     ments.  Alternative values for a parameter are separated with `|'.  If
     there are alternative values for a mandatory parameter, braces are used
     (together with `|') to enclose the value set.  Meta-variables are speci-
     fied within angles.

     Example:

           .Xx <foo> {bar1 | bar2} [-test1 [-test2 | -test3]] ...

     Except stated explicitly, all macros are parsed and callable.

     Note that a macro takes effect up to the next nested macro.  For example,
     `.Ic foo Aq bar' doesn't produce `foo <bar>' but `foo <bar>'.  Conse-
     quently, a warning message is emitted for most commands if the first
     argument is a macro itself since it cancels the effect of the calling
     command completely.  Another consequence is that quoting macros never
     insert literal quotes; `foo <bar>' has been produced by `.Ic "foo
     <bar>"'.

     Most macros have a default width value which can be used to specify a
     label width (-width) or offset (-offset) for the `.Bl' and `.Bd' macros.
     It is recommended not to use this rather obscure feature to avoid depen-
     dencies on local modifications of the -mdoc package.

TITLE MACROS
     The title macros are part of the page structure domain but are presented
     first and separately for someone who wishes to start writing a man page
     yesterday.  Three header macros designate the document title or manual
     page title, the operating system, and the date of authorship.  These
     macros are called once at the very beginning of the document and are used
     to construct headers and footers only.

     .Dt [<document title>] [<section number>] [<volume>]
             The document title is the subject of the man page and must be in
             CAPITALS due to troff limitations.  If omitted, `UNTITLED' is
             used.  The section number may be a number in the range 1, ..., 9
             or `unass', `draft', or `paper'.  If it is specified, and no vol-
             ume name is given, a default volume name is used.

             Under NetBSD 5.0_STABLE, the following sections are defined:

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

             A volume name may be arbitrary or one of the following:

                   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 vol-
             ume name.  If the third parameter is a keyword designating a com-
             puter architecture, its value is prepended to the default volume
             name as specified by the second parameter.  By default, the fol-
             lowing architecture keywords are defined:

                   alpha, acorn26, acorn32, algor, amd64, amiga, arc, arm26,
                   arm32, atari, bebox, cats, cesfic, cobalt, dreamcast,
                   evbarm, evbmips, evbppc, evbsh3, hp300, hp700, hpcmips,
                   i386, luna68k, m68k, mac68k, macppc, mips, mmeye, mvme68k,
                   mvmeppc, netwinder, news68k, newsmips, next68k, ofppc,
                   pc532, pmax, pmppc, powerpc, prep, sandpoint, sgimips, sh3,
                   shark, sparc, sparc64, sun3, tahoe, vax, x68k, x86_64

             If the section number is neither a numeric expression in the
             range 1 to 9 nor one of the above described keywords, the third
             parameter is used verbatim as the volume name.

             In the following examples, the left (which is identical to the
             right) and the middle part of the manual page header strings are
             shown.  Note how `\&' prevents the digit 7 from being a valid
             numeric expression.

                   .Dt FOO 7       `FOO(7)' `NetBSD Miscellaneous Information
                                   Manual'
                   .Dt FOO 7 bar   `FOO(7)' `NetBSD Miscellaneous Information
                                   Manual'
                   .Dt FOO \&7 bar
                                   `FOO(7)' `bar'
                   .Dt FOO 2 i386  `FOO(2)' `NetBSD/i386 System Calls Manual'
                   .Dt FOO "" bar  `FOO' `bar'

             Local, OS-specific additions might be found in the file
             mdoc.local; look for strings named `volume-ds-XXX' (for the for-
             mer type) and `volume-as-XXX' (for the latter type); `XXX' then
             denotes the keyword to be used with the `.Dt' macro.

             This macro is neither callable nor parsed.

     .Os [<operating system>] [<release>]
             If the first parameter is empty, the default `NetBSD 5.0_STABLE'
             is used.  This may be overridden in the local configuration file,
             mdoc.local.  In general, the name of the operating system should
             be the common acronym, e.g. BSD or ATT.  The release should be
             the standard release nomenclature for the system specified.  In
             the following table, the possible second arguments for some pre-
             defined operating systems are listed.  Similar to `.Dt', local
             additions might be defined in mdoc.local; look for strings named
             `operating-system-XXX-YYY', where `XXX' is the acronym for the
             operating system and `YYY' the release ID.

                   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, 2.0, 2.0.1, 2.0.2, 2.1

                   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, 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, 5.0, 5.1, 5.2, 5.2.1, 5.3

             For ATT, an unknown second parameter will be replaced with the
             string UNIX; for the other predefined acronyms it will be ignored
             and a warning message emitted.  Unrecognized arguments are dis-
             played as given in the page footer.  For instance, a typical
             footer might be:

                   .Os BSD 4.3

             giving `4.3 Berkeley Distribution', or for a locally produced set

                   .Os CS Department

             which will produce `CS Department'.

             If the `.Os' macro is not present, the bottom left corner of the
             manual page will be ugly.

             This macro is neither callable nor parsed.

     .Dd [<month> <day>, <year>]
             If `Dd' has no arguments, `Epoch' is used for the date string.
             If it has exactly three arguments, they are concatenated, sepa-
             rated with unbreakable space:

                   .Dd January 25, 2001

             The month's name shall not be abbreviated.

             With any other number of arguments, the current date is used,
             ignoring the parameters.

             This macro is neither callable nor parsed.

INTRODUCTION OF 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(1) 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 content 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 which 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 confu-
     sion, 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 content macros are capable of recog-
     nizing and properly handling punctuation, provided each punctuation char-
     acter 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 distin-
     guishing 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 a member of the mathematical, logical or quota-
     tion set:

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

     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 `\&'.  Typi-
     cal syntax is shown in the first content 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 the AUTHORS section, the `.An' command causes a line 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, the `file ...' string is output.

           Usage: .Ar [<argument>] ...

                    .Ar              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(1) declaration for a
     device interface in a section four manual.

           Usage: .Cd <argument> ...

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

     In the SYNOPSIS section a `.Cd' command causes a line break before and
     after its arguments are printed.

     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) which 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.

   Errno's
     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, which 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 the SYNOPSIS section a `.Fd' command causes a line break if a function
     has already been presented and a break has not occurred.  This leaves a
     nice vertical space in between the previous function call and the decla-
     ration for the next function.

     The `.In' macro, while in the SYNOPSIS section, 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 line
     break.

     While not in the SYNOPSIS section, it represents the header file enclosed
     in angle brackets.

           Usage: .In <header file>

                    .In stdio.h  #include <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 kernel normal form for the SYNOPSIS of sections two
     and three (it causes a line 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' (func-
     tion 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)

     In the SYNOPSIS section, the function will always begin at the beginning
     of line.  If there is more than one function presented in the SYNOPSIS
     section and a function type has not been given, a line break will occur,
     leaving a nice vertical space between the current function name and the
     one prior.

     The default width values of `.Fn' and `.Fo' are 12n and 16n, respec-
     tively.

   Function Arguments
     The `.Fa' macro is used to refer to function arguments (parameters) out-
     side 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.  Cur-
     rently, 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.  Cur-
     rently, 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 func-
     tion is compiled in.

           Usage: .Lb <argument> ...

     Available arguments to `.Lb' and their results are:

           libarm       ARM Architecture Library (libarm, -larm)
           libarm32     ARM32 Architecture Library (libarm32, -larm32)
           libc         Standard C Library (libc, -lc)
           libcdk       Curses Development Kit Library (libcdk, -lcdk)
           libcompat    Compatibility Library (libcompat, -lcompat)
           libcrypt     Crypt Library (libcrypt, -lcrypt)
           libcurses    Curses Library (libcurses, -lcurses)
           libedit      Command Line Editor Library (libedit, -ledit)
           libevent     Event Notification Library (libevent, -levent)
           libform      Curses Form Library (libform, -lform)
           libi386      i386 Architecture Library (libi386, -li386)
           libintl      Internationalized Message Handling Library (libintl,
                        -lintl)
           libipsec     IPsec Policy Control Library (libipsec, -lipsec)
           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)
           libmenu      Curses Menu Library (libmenu, -lmenu)
           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)
           libpthread   POSIX Threads Library (libpthread, -lpthread)
           libresolv    DNS Resolver Library (libresolv, -lresolv)
           librt        POSIX Real-time Library (librt, -lrt)
           libtermcap   Termcap Access Library (libtermcap, -ltermcap)
           libusbhid    USB Human Interface Devices Library (libusbhid,
                        -lusbhid)
           libutil      System Utilities Library (libutil, -lutil)
           libx86_64    x86_64 Architecture Library (libx86_64, -lx86_64)
           libz         Compression Library (libz, -lz)

     Local, OS-specific additions might be found in the file mdoc.local; look
     for strings named `str-Lb-XXX'.  `XXX' then denotes the keyword to be
     used with the `.Lb' macro.

     In the LIBRARY section an `.Lb' command causes a line break before and
     after its arguments are printed.

   Literals
     The `.Li' literal macro may be used for special characters, variable con-
     stants, etc. -- anything which should be displayed as it would be typed.

           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 subject name.  It has
     the peculiarity of remembering the first argument it was called with,
     which should always be the subject name of the page.  When called without
     arguments, `.Nm' regurgitates this initial name for the sole purpose of
     making less work for the author.  Note: A section two or three document
     function name is addressed with the `.Nm' in the NAME section, and with
     `.Fn' in the SYNOPSIS and remaining sections.  For interactive commands,
     such as the `while' command keyword in csh(1), the `.Ic' macro should be
     used.  While `.Ic' is nearly identical to `.Nm', it can not recall the
     first argument it was invoked with.

           Usage: .Nm [<argument>] ...

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

     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 brack-
     ets.  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, respec-
     tively.

   Pathnames
     The `.Pa' macro formats path or file names.  If called without arguments,
     the `~' string is output, which represents the current user's home direc-
     tory.

           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'')

     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'')

     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

           -susv2          Version 2 of the Single UNIX Specification
                           (``SUSv2'')
           -svid4          System V Interface Definition, Fourth Edition
                           (``SVID4'')
           -xbd5           X/Open System Interface 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
           -iso8802-3      ISO/IEC 8802-3:1989

   Variable Types
     The `.Vt' macro may be used whenever a type is referenced.  In the
     SYNOPSIS section, it causes a line break (useful for old style 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, 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.

   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 irregu-
     larities.  For each enclosure macro there is also a pair of open and
     close macros which end in small 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 XX)    XXstringXX
         .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  Due to the nine-argument limit in the original troff program
               two other macros have been implemented which are now rather
               obsolete: `.Es' takes the first and second parameter as the
               left and right enclosure string, 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
               mode.  If formatted with nroff, 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 func-
               tion.

     .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 '^[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.

   No-Op or Normal Text Macro
     The `.No' macro can be used in a macro command line for parameters which
     should not be formatted.  Be careful to add `\&' to the word `No' if you
     really want that English word (and not the macro) as a parameter.

           Usage: .No <argument> ...

                    .No test Ta with Ta tabs  test     with     tabs

     The default width is 12n.

   No-Space Macro
     The `.Ns' macro suppresses insertion of a space between the current posi-
     tion 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'.

   Section Cross References
     The `.Sx' macro designates a reference to a section header within the
     same 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).  Causes a line
                   break in the SEE ALSO section and begins collection of ref-
                   erence 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 (not implemented yet).
           .%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.
           .%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 parame-
     ter; 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, 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 and Type Names)
     The trade name macro prints its arguments in a smaller font.  Its
     intended use is to imitate a small caps fonts for uppercase 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 enclo-
     sure (without inserting characters, of course).  This means that the fol-
     lowing is true for those macros also.

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

           .Sm off
           .It Xo Sy I Ar operation
           .No \en Ar count No \en
           .Xc
           .Sm on

     produces

           Ioperation\ncount\n

     Another one:

           .Sm off
           .It Cm S No / Ar old_pattern Xo
           .No / Ar new_pattern
           .No / Op Cm g
           .Xc
           .Sm on

     produces

           S/old_pattern/new_pattern/[g]

     Another example of `.Xo' and enclosure macros: Test the value of a vari-
     able.

           .It Xo
           .Ic .ifndef
           .Oo \&! Oc Ns Ar variable Oo
           .Ar operator variable ...
           .Oc Xc

     produces

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

PAGE STRUCTURE DOMAIN
   Section Headers
     The following `.Sh' section header macros are required in every man page.
     The remaining section headers are recommended at the discretion of the
     author writing the manual page.  The `.Sh' macro is parsed but not gener-
     ally 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

     .Sh DESCRIPTION    In most cases the first text in the DESCRIPTION sec-
                        tion 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 headers 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 sub-
                        ject should be listed via the `.Pa' macro in the FILES
                        section.

     .Sh EXAMPLES       There are several ways to create examples.  See the
                        EXAMPLES section 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 sec-
                        tion 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 func-
                        tions (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 are sorted
                        on the section number, then alphabetically on the
                        names within a section, and placed in that order and
                        comma separated.  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 sec-
                        tion.

     .Sh AUTHORS        Credits should be placed here.  Use the `.An' macro
                        for names and the `.Aq' macro for e-mail addresses
                        within optional contact information.  Explicitly indi-
                        cate 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 Headers
     Subsection headers have exactly the same syntax as section headers: `.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'
     accepts currently is -words (this is also the default if no option is
     given) which is useful for preventing line breaks in the middle of
     options.  In the example for the make command line arguments (see What's
     in a Name), the keep prevented nroff from placing up the flag and the
     argument on separate lines.

     Both macros are neither callable nor parsed.

     More work needs to be done with 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; display a block of text as typed,
                             using line breaks as specified by the user.  This
                             can produce overlong lines without warning mes-
                             sages.
          -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.
          -file <file 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 pro-
                             cessed.
          -offset <string>   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 mar-
                                         gin; 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 per-
                                         haps may never do the right thing
                                         within troff.

                             If <string> is a valid numeric expression instead
                             (with a scale indicator other than `u'), use that
                             value for indentation.  The most useful scale
                             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 scale
                             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 unproven.

     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:

                    o   Bullet one goes here.
                    o   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's 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-pos-
                          itive 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
                    .Tn I/O Ns 's
                    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's 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
                    .Tn I/O Ns 's
                    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 con-
                    strained.

                    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
                    .Nm -mdoc
                    manuals to other formats.
                    .El

     -column  This list type generates multiple columns.  The number of col-
              umns 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

     Other keywords:

     -width <string>   If <string> starts with a `.' (dot) immediately fol-
                       lowed 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:

                       -test <string>  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, argu-
                       ments 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 scale indicator other than `u'), use that value
                       for indentation.  The most useful scale 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 scale 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,
                       every time `.It' is invoked, an attempt is made to
                       determine an appropriate width.  If the first argument
                       to `.It' is a callable macro, the default width for
                       that macro will be used; otherwise, the default width
                       of `.No' is used.

     -offset <string>  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 scale indicator other than `u'), use
                       that value for indentation.  The most useful scale
                       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 scale 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
     Here a list of the remaining macros which do not fit well into one of the
     above sections.  We couldn't find real examples for the following macros:
     `.Me' and `.Ot'.  They are documented here for completeness - if you know
     how to use them properly please send a mail to bug-groff@gnu.org (includ-
     ing an example).

     .Bt  prints

                is currently in beta test.

          It is neither callable nor parsed and takes no arguments.

     .Fr

                Usage: .Fr <function return value> ...

          Don't use this macro.  It allows a break right before the return
          value (usually a single digit) which is bad typographical behaviour.
          Use `\~' to tie the return value to the previous word.

     .Hf  Use this macro to include a (header) file literally.  It first
          prints `File:' followed by the file name, then the contents of
          <file>.

                Usage: .Hf <file>

          It is neither callable nor parsed.

     .Lk  link (for conversion to HTML).

                Usage: .Lk <href> [anchor-text]

     .Me  Exact usage unknown.  The documentation in the -mdoc source file
          describes it as a macro for ``menu entries''.

          Its default width is 6n.

     .Mt  mailto (for conversion to HTML).

                Usage: .Mt <email_address>

     .Ot  Exact usage unknown.  The documentation in the -mdoc source file
          describes it as ``old function type (fortran)''.

     .Sm  Activate (toggle) space mode.

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

          If space 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 space mode.

     .Ud  prints

                currently under development.

          It is neither callable nor parsed and takes no arguments.

PREDEFINED STRINGS
     The following strings are predefined:

           String    Nroff       Troff     Meaning
           <=        <=          <=        less equal
           >=        >=          >=        greater equal
           Rq        ''          ''        right double quote
           Lq        ``          ``        left double quote
           ua        ^           ^         upwards arrow
           aa        '           '         acute accent
           ga        `           `         grave accent
           q         "           "         straight double quote
           Pi        pi          pi        greek pi
           Ne        !=          !=        not equal
           Le        <=          <=        less equal
           Ge        >=          >=        greater equal
           Lt        <           <         less than
           Gt        >           >         greater than
           Pm        +-          +-        plus minus
           If        infinity    infinity  infinity
           Am        &           &         ampersand
           Na        NaN         NaN       not a number
           Ba        |           |         vertical bar

     The names of the columns Nroff and Troff are a bit misleading; Nroff
     shows the ASCII representation, while Troff gives the best glyph form
     available.  For example, a Unicode enabled TTY-device will have proper
     glyph representations for all strings, whereas the enhancement for a
     Latin1 TTY-device is only the plus-minus sign.

     String names which consist of two characters can be written as `\*(xx';
     string names which consist of one character can be written as `\*x'.  A
     generic syntax for a string name of any length is `\*[xxx]' (this is a
     GNU troff(1) extension).

DIAGNOSTICS
     The debugging macro `.Db' available in previous versions of -mdoc has
     been removed since GNU troff(1) provides better facilities to check
     parameters; additionally, many error and warning messages have been added
     to this macro package, making it both more robust and verbose.

     The only remaining debugging macro is `.Rd' which yields a register dump
     of all global registers and strings.  A normal user will never need it.

FORMATTING WITH GROFF, TROFF, AND NROFF
     By default, the package inhibits page breaks, headers, and footers if
     displayed with a TTY device like `latin1' or `unicode', to make the man-
     ual more efficient for viewing on-line.  This behaviour can be changed
     (e.g. to create a hardcopy of the TTY output) by setting the register
     `cR' to zero while calling groff(1), resulting in multiple pages instead
     of a single, very long page:

           groff -Tlatin1 -rcR=0 -mdoc foo.man > foo.txt

     For double-sided printing, set register `D' to 1:

           groff -Tps -rD1 -mdoc foo.man > foo.ps

     To change the document font size to 11pt or 12pt, set register `S'
     accordingly:

           groff -Tdvi -rS11 -mdoc foo.man > foo.dvi

     Register `S' is ignored for TTY devices.

     The line and title length can be changed by setting the registers `LL'
     and `LT', respectively:

           groff -Tutf8 -rLL=100n -rLT=100n -mdoc foo.man | less

     If not set, both registers default to 78n for TTY devices and 6.5i other-
     wise.

FILES
     doc.tmac          The main manual macro package.
     mdoc.tmac         A wrapper file to call doc.tmac.
     mdoc/doc-common   Common strings, definitions, stuff related typographic
                       output.
     mdoc/doc-nroff    Definitions used for a TTY output device.
     mdoc/doc-ditroff  Definitions used for all other devices.
     mdoc.local        Local additions and customizations.
     andoc.tmac        This file checks whether the -mdoc or the -man package
                       should be used.

SEE ALSO
     groff(1), man(1), troff(1), groff_man(7)

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

     `.Nm' font should be changed in NAME section.

     `.Fn' needs to have a check to prevent splitting up if the line length is
     too short.  Occasionally it separates the last parenthesis, and sometimes
     looks ridiculous if a line is in fill mode.

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

NetBSD 5.0_STABLE               August 28, 2005              NetBSD 5.0_STABLE
