MDOC.SAMPLES(7)            OpenBSD Reference Manual            MDOC.SAMPLES(7)

NAME
     mdoc.samples - tutorial sampler for writing OpenBSD manuals with -mdoc

SYNOPSIS
     nroff -TName -mandoc file

DESCRIPTION
     A tutorial sampler for writing OpenBSD manual pages with the -mdoc macro
     package, a content-based and domain-based formatting package for
     troff(1).  Its predecessor, the -man package (see man(7)) 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 con-
     sists of macros for titles, section headers, displays and lists.  Essen-
     tially items which affect the physical position of text on a formatted
     page.  In addition to the page structure domain, there are two more do-
     mains: 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 de-
     scribe commands, routines and related OpenBSD files.  Macros in the manu-
     al domain handle command names, command line arguments and options, func-
     tion 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.  It is hoped the con-
     sistency 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
     Since a tutorial document is normally read when a person desires to use
     the material immediately, the assumption has been made that the user of
     this document may be impatient.  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 (a warning).
                      Escaping Special Characters.
                      Dashes and Hyphens.

           2.   THE ANATOMY OF A MAN PAGE
                      A manual page template.

           3.   TITLE MACROS

           4.   INTRODUCTION TO MANUAL AND GENERAL TEXT DOMAINS
                      What's in a name....
                      General Syntax.

           5.   MANUAL DOMAIN
                      Addresses.
                      Arguments.
                      Authors.
                      Command Modifier.
                      Configuration Declarations (section four only).
                      Defined Variables.
                      Environment Variables.
                      Errno (section two only).
                      Exit Values.
                      Flags.
                      Functions (library routines).
                      Function Argument.
                      Function Declaration.
                      Function Types.
                      Interactive Commands.
                      Includes.
                      Literals.
                      Names.
                      Options.
                      Pathnames.
                      Return Values.
                      Standards.
                      Variables.
                      Cross References.

           6.   GENERAL TEXT DOMAIN
                      AT&T Macro.
                      BSD Macro.
                      BSDI Macro.
                      OpenBSD/FreeBSD/NetBSD Macros.
                      UNIX Macro.
                      Emphasis Macro.
                      Font mode.
                      Enclosure and Quoting Macros
                                  Angle Bracket Quote/Enclosure.
                                  Bracket Quote/Enclosure.
                                  Double Quote macro/Enclosure.
                                  Enclose String macro.
                                  Parenthesis Quote/Enclosure.
                                  Quoted Literal macro/Enclosure.
                                  Straight Double Quote macro/Enclosure.
                                  Single Quote macro/Enclosure.
                      No-Op or Normal Text Macro.
                      No Space Macro.
                      Prefix Macro.
                      Section Cross References.
                      Space Mode Macro.
                      Symbolic Macro.
                      Mathematical Symbols.
                      References and Citations.
                      Trade Names (or Acronyms and Type Names).
                      Extended Arguments.
                      Miscellaneous Macros.

           7.   PAGE STRUCTURE DOMAIN
                      Section Headers.
                      Paragraphs and Line Spacing.
                      Keeps.
                      Displays.
                      Lists and Columns.

           8.   PREDEFINED STRINGS

           9.   DIAGNOSTICS

           10.  FORMATTING WITH GROFF, TROFF AND NROFF

           11.  FILES

           12.  SEE ALSO

           13.  BUGS

TROFF IDIOSYNCRASIES
     The -mdoc package attempts to simplify the process of writing a man page.
     Theoretically, one should not have to learn the dirty details of 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 troff(1), a macro is called by placing a `.' (dot character) at the
     beginning of a line followed by the two-character name for the macro.
     Arguments may follow the macro separated by spaces.  It is the dot char-
     acter at the beginning of the line which causes troff(1) to interpret the
     next two characters as a macro name.  To place a `.' (dot character) at
     the beginning of a line in some context other than a macro invocation,
     precede the `.' (dot) with the `\&' escape sequence.  The `\&' translates
     literally to a zero-width space, and is never displayed in the output.

     In general, troff(1) macros accept up to nine arguments; any extra argu-
     ments are ignored.  Most macros in -mdoc accept nine arguments and, in
     limited cases, arguments may be continued or extended on the next line
     (see Extended Arguments).  A few 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 is determined to be callable will be exe-
     cuted or called when it is processed.  In this case the argument, al-
     though the name of a macro, is not preceded by a `.' (dot).  It is in
     this manner that many macros are nested; 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 two-character 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 and in the companion quick refer-
     ence manual mdoc(7).  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.

   Passing Space Characters in an Argument
     Sometimes it is desirable to give as one argument a string containing one
     or more blank space characters.  This may be necessary to defeat the nine
     argument limit or to specify arguments to macros which expect particular
     arrangement of items in the argument list.  For example, the function
     macro `.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.  Implementation note: Unfortunately, the most convenient way
     of passing spaces in between quotes by reassigning individual arguments
     before parsing was fairly expensive speed wise and space wise to imple-
     ment in all the macros for AT&T troff(1).  It is not expensive for
     groff(1) but for the sake of portability, has been limited to the follow-
     ing macros which need it the most:

           Bl    Begin list (for the width specifier).
           Cd    Configuration declaration (section 4 SYNOPSIS).
           Em    Emphasized text.
           Fn    Functions (sections two and four).
           It    List items.
           Li    Literal text.
           Sy    Symbolic text.
           %B    Book titles.
           %J    Journal names.
           %O    Optional notes for a reference.
           %R    Report title (in a reference).
           %T    Title of article in a book or journal.

     One way of passing a string containing blank spaces is to use the hard or
     unpaddable space character `\ ', that is, a blank space preceded 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 newline
     separated pieces as one would expect.  The method is useful for strings
     which are not expected to overlap a line boundary.

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

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

     If the `\' or quotes were omitted, `.Fn' would see three arguments and
     the result would be:

           fetch(char, *str)

     For an example of what happens when the parameter list overlaps a newline
     boundary, see the BUGS section.

   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
     force 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 re-
     placing the `\' with `\e' (e.g., `\en') to preserve the backslash.

   Dashes and Hyphens
     In typography there are different types of dashes of various width: the
     hyphen (-), the minus sign (-), the en-dash (-), and the em-dash (--).

     Hyphens are used for adjectives; to separate the two parts of a compound
     word; or to separate a word across two successive lines of text.  The hy-
     phen does not need to be escaped:

           blue-eyed
           lorry-driver

     The mathematical minus sign is used for negative numbers or subtraction.
     It should be written as `\-':

           a = 3 \- 1;
           b = \-2;

     The en-dash is used to separate the two elements of a range, or can be
     used the same way as an em-dash.  It should be written as `\(en':

           pp. 95\(en97.
           Go away \(en or else!

     The em-dash can be used to show an interruption or can be used the same
     way as colons, semi-colons, or parentheses.  It should be written as
     `\(em':

           Three things \(em apples, oranges, and bananas.
           This is not that \(em rather, this is that.

     Note: hyphens, minus signs, and en-dashes look identical under normal
     ASCII output.  Other formats, such as PostScript, render them correctly,
     with differing widths.

THE ANATOMY OF A MAN PAGE
     The body of a man page is easily constructed from a basic template found
     in the file /usr/share/misc/mdoc.template.

           .\" The following requests are required for all man pages.
           .Dd $Mdocdate$
           .Dt NAME SECTION#
           .Os
           .Sh NAME
           .Nm program
           .Nd one line about what it does
           .Sh SYNOPSIS
           .\" For a program:  program [-abc] file ...
           .Nm program
           .Op Fl abc
           .Ar
           .Sh DESCRIPTION
           The
           .Nm
           utility processes files ...
           .\" The following requests should be uncommented
           .\"  and used where appropriate.
           .\" This next request is for sections 2, 3, and 9
           .\"  function return values only.
           .\" .Sh RETURN VALUES
           .\" This next request is for sections 1, 6, 7 & 8 only.
           .\" .Sh ENVIRONMENT
           .\" .Sh FILES
           .\" .Sh EXAMPLES
           .\" This next request is for sections 1, 4, 6, and 8 only.
           .\" .Sh DIAGNOSTICS
           .\" The next request is for sections 2, 3, and 9
           .\"  error and signal handling only.
           .\" .Sh ERRORS
           .\" .Sh SEE ALSO
           .\" .Xr foobar 1
           .\" .Sh STANDARDS
           .\" .Sh HISTORY
           .\" .Sh AUTHORS
           .\" .Sh CAVEATS
           .\" .Sh BUGS

     The first items in the template are the macros (.Dd, .Dt, .Os); the docu-
     ment date, the man page title (in upper case) along with the section of
     the manual the page belongs in, and the operating system the man page or
     subject source is developed or modified for.  These macros identify 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.

TITLE MACROS
     The title macros are the first portion of the page structure domain, but
     are presented first and separate 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 document
     change (or creation).  These macros are called once at the very beginning
     of the document and are used to construct the headers and footers only.

     .Dd $Mdocdate$
             The literal string ``$Mdocdate$'', which is expanded by cvs(1) to
             the date a document is committed to a source repository.

             Alternatively the date may be written by hand.  The date should
             be written formally:

                   .Dd January 25, 1989

     .Dt DOCUMENT_TITLE section# [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'.  The following section numbers are
             defined:

                   1    General commands (tools and utilities)
                   2    System calls and error numbers
                   3    Libraries
                   3p   perl(1) programmer's reference guide
                   4    Device drivers
                   5    File formats
                   6    Games
                   7    Miscellaneous
                   8    System maintenance and operation commands
                   9    Kernel internals

             The volume title is optional; if specified, it should be one of
             the following:

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

             The default volume labeling is URM for sections 1, 6, and 7; SMM
             for section 8; PRM for sections 2, 3, 4, and 5; KM for section 9.

             If the third argument to `.Dt' is instead a machine architecture,
             it will be displayed, surrounded by parentheses, next to the vol-
             ume title.  This is useful for pages specific only to a particu-
             lar architecture.  The architectures currently defined are:

                   alpha, amd64, amiga, arc, armish, aviion, hp300,
                   hppa, hppa64, i386, landisk, loongson, luna88k,
                   mac68k, macppc, mvme68k, mvme88k, mvmeppc, pmax,
                   sgi, socppc, sparc, sparc64, sun3, vax, zaurus

     .Os operating_system release#
             The name of the operating system should be a common acronym,
             e.g., OpenBSD or ATT.  The release should be the standard release
             nomenclature for the system specified, e.g., 4.3, 4.3+Tahoe, V.3,
             V.4.  Unrecognized arguments are displayed as given in the page
             footer.  For instance, a typical footer might be:

                   .Os OpenBSD 3.4

             or for a locally produced set

                   .Os "CS Department"

             The OpenBSD default, `.Os' without an argument, is defined as
             OpenBSD <latest release#> in the site specific file
             /usr/share/tmac/mdoc/doc-common.  It really should default to
             LOCAL.  Note, if the `.Os' macro is not present, the bottom left
             corner of the page will be ugly.

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 de-
     scription of -mdoc macro request 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(1) command is:

           .Va argument1 argument2 ... argument9

     The `.Va' is a macro command or request, and anything following it is an
     argument 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 arguments.  The macros which formatted the
     above example:

           .Nm filter
           .Op Fl flag
           .Ar infile outfile

     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
           .Bk -words
           .Op Fl I Ar directory
           .Ek
           .Op Fl j Ar max_jobs
           .Op Ar variable=value
           .Op Ar target ...

     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: `.Ar', `.Fl', `.Nm', and `.Pa' differ only
     when called without arguments; `.Fn' and `.Xr' impose an order on their
     argument lists and the `.Op' and `.Fn' macros have nesting limitations.
     All content macros are capable of recognizing and properly handling punc-
     tuation, provided each punctuation character is separated by a leading
     space.  If a request is given:

           .Ar sptr, ptr),

     The result is:

           sptr, ptr),

     The punctuation is not recognized and everything is output in the font
     used by `.Ar'.  If the punctuation is separated by a leading whitespace:

           .Ar sptr , ptr ) ,

     The result is:

           sptr, ptr),

     The punctuation is now recognized and is output in the default font dis-
     tinguishing it from the argument strings.  To remove the special meaning
     from a punctuation character escape it with `\&'.  The following punctua-
     tion characters are recognised 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(1) may assume it is supposed to actually per-
     form 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 content macro displayed below,
     `.Ad'.

MANUAL DOMAIN
   Address Macro
     The address macro identifies an address construct of the form addr1[,ad-
     dr2[,addr3]].

           Usage: .Ad address ... { . , ; : ? ! ( ) [ ]}

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

     It is an error to call `.Ad' without arguments.  The `.Ad' macro is
     parsed and is callable.

   Argument Macro
     The `.Ar' argument macro may be used whenever a command line argument is
     referenced.

           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)),

     If `.Ar' is called without arguments, `file ...' is assumed.  The `.Ar'
     macro is parsed and is callable.

   Author Name
     The `.An' macro is used to specify the name of the author of the utility,
     or the name of the author of the man page.

           Usage: .An -nosplit | -split | author ... { . , ; : ? ! ( ) [ ]}

           .An John Smith        John Smith
           .An John Smith ,      John Smith,
           .An John Smith Aq john@email.address
                                 John Smith <john@email.address>

     In the AUTHORS section, `.An' causes a line break to occur before the au-
     thor name.  The arguments -nosplit and -split can be used to toggle this
     behavior.  For example:

           .Sh AUTHORS
           .An -nosplit
           The
           .Nm
           utility was written by
           .An John Smith Aq john@email.address
           and
           .An Jane Doe Aq jane@email.address .

     The `.An' macro is parsed, but is not callable.

   Command Modifier
     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; 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.

   Configuration Declaration (section four only)
     The `.Cd' macro is used to demonstrate a config(8) declaration for a de-
     vice interface in a section four manual.  This macro accepts quoted argu-
     ments (double quotes only).

           device le0 at scode?  produced by: `.Cd device le0 at scode?'.

     It is an error to call `.Cd' without arguments.  The `.Cd' macro is nei-
     ther parsed nor callable.

   Defined Variables
     A variable which is defined in an include file is specified by the macro
     `.Dv'.

           Usage: .Dv defined_variable ... { . , ; : ? ! ( ) [ ]}

                   .Dv MAXHOSTNAMELEN  MAXHOSTNAMELEN
                   .Dv TIOCGPGRP )     TIOCGPGRP)

     It is an error to call `.Dv' without arguments.  The `.Dv' macro is
     parsed and is callable.

   Environment Variables
     The `.Ev' macro specifies an environment variable.

           Usage: .Ev argument ... { . , ; : ? ! ( ) [ ]}

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

     It is an error to call `.Ev' without arguments.  The `.Ev' macro is
     parsed and is callable.

   Errno (section two only)
     The `.Er' errno macro specifies the error return value for section two
     library routines.  The third 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 ERRNOTYPE ... { . , ; : ? ! ( ) [ ]}

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

     It is an error to call `.Er' without arguments.  The `.Er' macro is
     parsed and is callable.

   Exit Values (sections one, six, and eight only)
     The `.Ex' macro displays a standardised text concerning the exit values
     of applications.  The `.Ex' macro is neither parsed nor callable.  The
     `-std' flag is purely for compatibility purposes, and must be included.

           Usage: .Ex [-std] utility

     For example, `.Ex -std cat' produces:

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

   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.
                   .Fl s v t     -s -v -t
                   .Fl - ,       --,
                   .Fl xyz ) ,   -xyz),

     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 `.Fl' macro is parsed and is callable.

   Functions (library routines)
     The `.Fn' macro is modeled on ANSI C conventions.

     Usage: .Fn [type] function [[type] parameters ... { . , ; : ? ! ( ) [ ]}]

     .Fn getchar                             getchar()
     .Fn strlen ) ,                          strlen()),
     .Fn "int align" "const * char *sptrs",  int align(const * char *sptrs),

     It is an error to call `.Fn' without any arguments.  The `.Fn' macro is
     parsed and is callable.  Note that any call to another macro signals the
     end of the `.Fn' call (it will close-parenthesis at that point).

     For functions that have more than eight parameters (and this is rare),
     the macros `.Fo' (function open) and `.Fc' (function close) may be used
     with `.Fa' (function argument) to get around the limitation.  For exam-
     ple:

           .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)

     The `.Fo' and `.Fc' macros are parsed and are callable.  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.  At
     the moment, `.Fn' does not check its word boundaries against troff(1)
     line lengths and may split across a newline ungracefully.  This will be
     fixed in the near future.

   Function Argument
     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
     should a parameter list be too long for the `.Fn' macro and the enclosure
     macros `.Fo' and `.Fc' must be 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

     It is an error to call `.Fa' without arguments.  The `.Fa' macro is
     parsed and is callable.

   Function Declaration
     The `.Fd' macro is used in the SYNOPSIS section with section two, three,
     and nine functions.  The `.Fd' macro is neither parsed nor callable.

           Usage: .Fd include_file (or defined variable)

     In the SYNOPSIS section a `.Fd' request 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.

   Function Type
     This macro is intended for the SYNOPSIS section.  It may be used anywhere
     else in the man page without problems, but in the SYNOPSIS section it
     causes a line break after its use.  Its main purpose is to present the
     function type in kernel normal form of a section two or three man page by
     forcing the function name to appear on the next line.

           Usage: .Ft type ... { . , ; : ? ! ( ) [ ]}

                   .Ft struct stat  struct stat

     The `.Ft' macro is neither parsed nor callable.

   Interactive Commands
     The `.Ic' macro designates an interactive or internal command.

           Usage: .Ic command ... { . , ; : ? ! ( ) [ ]}

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

     It is an error to call `.Ic' without arguments.  The `.Ic' macro is
     parsed and is callable.

   Includes
     The `.In' macro is used in the SYNOPSIS section with section two, three,
     and nine header files.  The `.In' macro is neither parsed nor callable.

           Usage: .In include_file

                   .In stdio.h      #include <stdio.h>

     In the SYNOPSIS section a `.In' request 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 include file.

   Literals
     The `.Li' literal macro may be used for special characters, variable con-
     stants, 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 `.Li' macro is parsed and is callable.

   Name Macro
     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.  However, `.Nm' should always be given
     an argument when used in the SYNOPSIS section.

     Note: a section two or three document function name is addressed with
     `.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 identi-
     cal to `.Nm', it can not recall the first argument it was invoked with.

           Usage: .Nm argument ... { . , ; : ? ! ( ) [ ]}

                   .Nm mdoc.samples    mdoc.samples
                   .Nm                 mdoc.samples
                   .Nm .               mdoc.samples.
                   .Nm \-mdoc          -mdoc
                   .Nm foo ) ) ,       foo)),

     The `.Nm' macro is parsed and is callable.

   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 `.Oc' and `.Oo' may be used across one or more lines.

           Usage: .Op options ... { . , ; : ? ! ( ) [ ]}

           .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]

     The `.Oc' and `.Oo' macros:

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

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

     The macros `.Op', `.Oc' and `.Oo' are parsed and are callable.

   Pathnames
     The `.Pa' macro formats path or file names.

           Usage: .Pa pathname { . , ; : ? ! ( ) [ ]}

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

     The `.Pa' macro is parsed and is callable.

   Return Values (sections two and three only)
     The `.Rv' macro displays a standardised text concerning the return values
     of functions.  The `.Rv' macro is neither parsed nor callable.  The
     `-std' flag is purely for compatibility purposes, and must be included.

           Usage: .Rv [-std] function

     For example, `.Rv -std open' produces:

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

   Standards
     The `.St' macro replaces standard abbreviature with its formal name.

           Usage: .St abbreviature

     Available pairs for ``Abbreviature/Formal Name'' are:

           -p1003.1-88     IEEE Std 1003.1-1988 (``POSIX'')
           -p1003.1-90     IEEE Std 1003.1-1990 (``POSIX'')
           -p1003.1-96     ISO/IEC 9945-1:1996 (``POSIX'')
           -p1003.1-2001   IEEE Std 1003.1-2001 (``POSIX'')
           -p1003.1-2004   IEEE Std 1003.1-2004 (``POSIX'')
           -p1003.1-2008   IEEE Std 1003.1-2008 (``POSIX'')
           -p1003.1        IEEE Std 1003.1 (``POSIX'')
           -p1003.1b       IEEE Std 1003.1b (``POSIX'')
           -p1003.1b-93    IEEE Std 1003.1b-1993 (``POSIX'')
           -p1003.1c-95    IEEE Std 1003.1c-1995 (``POSIX'')
           -p1003.1g-2000  IEEE Std 1003.1g-2000 (``POSIX'')
           -p1003.2-92     IEEE Std 1003.2-1992 (``POSIX.2'')
           -p1387.2-95     IEEE Std 1387.2-1995 (``POSIX.7.2'')
           -p1003.2        IEEE Std 1003.2 (``POSIX.2'')
           -p1387.2        IEEE Std 1387.2 (``POSIX.7.2'')
           -isoC-90        ISO/IEC 9899:1990 (``ISO C90'')
           -isoC-amd1      ISO/IEC 9899/AMD1:1995 (``ISO C90'')
           -isoC-tcor1     ISO/IEC 9899/TCOR1:1994 (``ISO C90'')
           -isoC-tcor2     ISO/IEC 9899/TCOR2:1995 (``ISO C90'')
           -isoC-99        ISO/IEC 9899:1999 (``ISO C99'')
           -ansiC          ANSI X3.159-1989 (``ANSI C'')
           -ansiC-89       ANSI X3.159-1989 (``ANSI C'')
           -ansiC-99       ANSI/ISO/IEC 9899-1999 (``ANSI C99'')
           -ieee754        IEEE Std 754-1985
           -iso8802-3      ISO 8802-3: 1989
           -xpg3           X/Open Portability Guide Issue 3 (``XPG3'')
           -xpg4           X/Open Portability Guide Issue 4 (``XPG4'')
           -xpg4.2         X/Open Portability Guide Issue 4.2 (``XPG4.2'')
           -xpg4.3         X/Open Portability Guide Issue 4.3 (``XPG4.3'')
           -xbd5           X/Open System Interface Definitions Issue 5
                           (``XBD5'')
           -xcu5           X/Open Commands and Utilities Issue 5 (``XCU5'')
           -xsh5           X/Open System Interfaces and Headers Issue 5
                           (``XSH5'')
           -xns5           X/Open Networking Services Issue 5 (``XNS5'')
           -xns5.2d2.0     X/Open Networking Services Issue 5.2 Draft 2.0
                           (``XNS5.2D2.0'')
           -xcurses4.2     X/Open Curses Issue 4 Version 2 (``XCURSES4.2'')
           -susv2          Version 2 of the Single UNIX Specification
           -susv3          Version 3 of the Single UNIX Specification
           -svid4          System V Interface Definition, Fourth Edition
                           (``SVID4'')

   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 *

     It is an error to call `.Vt' without any arguments.  The `.Vt' macro is
     parsed and is callable.

   Variables
     Generic variable reference:

           Usage: .Va variable ... { . , ; : ? ! ( ) [ ]}

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

     It is an error to call `.Va' without any arguments.  The `.Va' macro is
     parsed and is callable.

   Manual Page Cross References
     The `.Xr' macro expects the first argument to be a manual page name, and
     the second argument, if it exists, to be either a section number or punc-
     tuation.  Any remaining arguments are assumed to be punctuation.

           Usage: .Xr man_page [1,...,9] { . , ; : ? ! ( ) [ ]}

                   .Xr mdoc          mdoc
                   .Xr mdoc ,        mdoc,
                   .Xr mdoc 7        mdoc(7)
                   .Xr mdoc 7 ) ) ,  mdoc(7))),

     The `.Xr' macro is parsed and is callable.  It is an error to call `.Xr'
     without any arguments.

GENERAL TEXT DOMAIN
   AT&T Macro
           Usage: .At [v[1-7] | 32v | V[1-4]] ...

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

     The `.At' macro is neither parsed nor callable.  It accepts at most two
     arguments.  It cannot currently handle punctuation.

   BSD Macro
           Usage: .Bx [Version/release] ... { . , ; : ? ! ( ) [ ]}

                   .Bx          BSD
                   .Bx 4.3 .    4.3BSD.

     The `.Bx' macro is parsed, but is not callable.

   BSDI Macro
           Usage: .Bsx [Version/release] ... { . , ; : ? ! ( ) [ ]}

                   .Bsx          BSDI BSD/OS
                   .Bsx 3.0 .    BSDI BSD/OS 3.0.

     The `.Bsx' macro is parsed, but is not callable.

   OpenBSD/FreeBSD/NetBSD Macros
           Usage: .Ox [Version/release] ... { . , ; : ? ! ( ) [ ]}

                   .Ox          OpenBSD
                   .Ox 2.7 .    OpenBSD 2.7.

           Usage: .Fx [Version/release] ... { . , ; : ? ! ( ) [ ]}

                   .Fx          FreeBSD
                   .Fx 4.0 .    FreeBSD 4.0.

           Usage: .Nx [Version/release] ... { . , ; : ? ! ( ) [ ]}

                   .Nx          NetBSD
                   .Nx 1.5 .    NetBSD 1.5.

     The `.Ox', `.Fx', and `.Nx' macros are parsed, but are not callable.

   UNIX Macro
           Usage: .Ux ... { . , ; : ? ! ( ) [ ]}

                   .Ux          UNIX

     The `.Ux' macro is parsed, but is not callable.

   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 `.Em' macro is parsed and is callable.  It is an error to call `.Em'
     without arguments.

   Font Mode
     The `.Bf' font mode must end with the `.Ef' macro (which takes no argu-
     ments).  Font modes may be nested within other font modes.

           Usage: .Bf font mode

     Font mode must be one of the following:

           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.

   Enclosure and Quoting Macros
     The concept of enclosure is similar to quoting.  The object being to en-
     close 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.  These
     can be used across one or more lines of text and while they have nesting
     limitations, the one line quote macros can be used inside of them.


           Quote     Close    Open   Function                  Result
           .Aq      .Ac      .Ao     Angle Bracket Enclosure   <string>
           .Bq      .Bc      .Bo     Bracket Enclosure         [string]
           .Dq      .Dc      .Do     Double Quote              ``string''
                    .Ec      .Eo     Enclose String (in XX)    XXstringXX
           .Pq      .Pc      .Po     Parenthesis Enclosure     (string)
           .Ql                       Quoted Literal            `st' or string
           .Qq      .Qc      .Qo     Straight Double Quote     "string"
           .Sq      .Sc      .So     Single Quote              `string'

     Except for the irregular macros noted below, all of the quoting macros
     are parsed and callable.  All handle punctuation properly, as long as it
     is presented one character at a time and separated by spaces.  The quot-
     ing macros examine opening and closing punctuation to determine whether
     it comes before or after the enclosing string.  This makes some nesting
     possible.

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

     .Ql       The quoted literal macro behaves differently for troff(1) than
               nroff(1).  If formatted with nroff(1), a quoted literal is al-
               ways quoted.  If formatted with troff(1), an item is only quot-
               ed 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.

     Examples of quoting:
           .Aq                         <>
           .Aq Ar 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'

     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 were also built from the same underlying routines and are a good
     example of -mdoc macro usage at its worst.

   No-Op or Normal Text Macro
     The macro `.No' is a hack for words in a macro command line which should
     not be formatted and follows the conventional syntax for content macros.

   No Space Macro
     The `.Ns' macro eliminates unwanted spaces in between macro requests.  It
     is useful for old style argument lists where there is no space between
     the flag and argument:

           .Op Fl I Ns Ar directory    produces [-Idirectory]

     Note: the `.Ns' macro always invokes the `.No' macro after eliminating
     the space unless another macro name follows it.  The macro `.Ns' is
     parsed and is callable.

   Prefix Macro
     The `.Pf' macro eliminates unwanted spaces between its first and second
     arguments.

           .Pf ( Fa name2              produces (name2

     The prefix macro is parsed, but is not callable.

   Section Cross References
     The `.Sx' macro designates a reference to a section header within the
     same document.  The `.Sx' macro is parsed and is callable.

                   .Sx FILES     FILES

   Space Mode Macro
     The `.Sm' macro turns spacing on or off.  It is especially useful in sit-
     uations where the `.Ns' macro may be too clumsy to use.  An argument of
     either on or off must be specified, to turn spacing on or off, respec-
     tively.

           Usage: .Sm on | off

     See Extended Arguments (below) for example usage.

   Symbolic Macro
     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 `.Sy' macro is parsed and is callable.  Arguments to `.Sy' may be
     quoted.

   Mathematical Symbols
     Use this macro for mathematical symbols.

           Usage: .Ms mathematical symbol ... { . , ; : ? ! ( ) [ ]}

                   .Ms sigma  sigma

     The `.Ms' macro is parsed, but is not callable.

   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.  Causes a line break and begins collection
                   of reference information until the reference end macro is
                   read.
           .Re     Reference End.  The reference is printed.
           .%A     Reference author name, one name per invocation.
           .%B     Book title.
           .%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(s).

     The macros beginning with `%' are not callable, and are parsed only for
     the trade name macro which returns to its caller.  (And not very pre-
     dictably at the moment either.)  The purpose is to allow trade names to
     be pretty printed in troff(1)/ditroff output.

   Trade Names (or Acronyms and Type Names)
     The trade name macro is generally a small caps macro for all upper case
     words longer than two characters.

           Usage: .Tn symbol ... { . , ; : ? ! ( ) [ ]}

                   .Tn DEC    DEC
                   .Tn ASCII  ASCII

     The `.Tn' macro is parsed and is callable.

   Extended Arguments
     The `.Xo' and `.Xc' macros allow one to extend an argument list on a
     macro boundary.  Argument lists cannot be extended within a macro which
     expects all of its arguments on one line such as `.Op'.

     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 using enclosure macros: Test the value of an
     variable.

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

     Produces

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

     All of the above examples have used the `.Xo' macro on the argument list
     of the `.It' (list-item) macro.  The extend macros are not used very of-
     ten, and when they are it is usually to extend the list-item argument
     list.  Unfortunately, this is also where the extend macros are the most
     finicky.  In the first two examples, spacing was turned off; in the
     third, spacing was desired in part of the output but not all of it.  To
     make these macros work in this situation make sure the `.Xo' and `.Xc'
     macros are placed as shown in the third example.  If the `.Xo' macro is
     not alone on the `.It' argument list, spacing will be unpredictable.  The
     `.Ns' (no space macro) must not occur as the first or last macro on a
     line in this situation.

   Miscellaneous Macros
     These macros are documented for the sake of completeness.

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

     .Hf     Includes a (header) file literally.  Prints ``File:'' followed by
             the file name, then the contents of the file.

                   Usage: .Hf file

     .Fr     Function return value.  Obsolete.

                   Usage: .Fr return value

     .Ot     Usage unknown.  The -mdoc macro package describes it as ``old
             function type (fortran)''.

     .Ud     Prints ``currently under development.''

PAGE STRUCTURE DOMAIN
   Section Headers
     The first three `.Sh' section header macros listed below 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 can
     take up to nine arguments.  The `.Sh' macro is neither parsed nor
     callable.

     .Sh NAME      The `.Sh NAME' macro is mandatory.  If not specified, the
                   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 possi-
                   ble, as the space available is small.

     .Sh SYNOPSIS  The SYNOPSIS section describes the typical usage of the
                   subject of a man page.  The macros required are either
                   `.Nm', `.Cd', `.Fn', (and possibly `.Fo', `.Fc', `.Fd',
                   `.Ft' macros).  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, 8.
                   Section 4 manuals require a `.Nm', `.Fd', or a `.Cd' con-
                   figuration 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

                   Note: The macros `.Op', `.Fl', and `.Ar' recognize the pipe
                   bar character `|', so a command line such as:

                         .Op Fl a | b

                   will not go orbital.  Troff normally interprets a | as a
                   special operator.  See PREDEFINED STRINGS for a usable |
                   character in other situations.

     .Sh DESCRIPTION
                   In most cases the first text in the DESCRIPTION section is
                   a brief paragraph on the command, function or file, fol-
                   lowed by a lexical list of options and respective explana-
                   tions.  To create such a list, the `.Bl' begin-list, `.It'
                   list-item and `.El' end-list macros are used (see Lists and
                   Columns below).

     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 RETURN VALUES
               Sections 2, 3, and 9 function return values.

     .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 the EXAMPLES
               section below for details.

     .Sh DIAGNOSTICS
               Diagnostics from a command should be placed in this section.

     .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 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.  Cross references in the SEE ALSO section should
               be sorted by section number, and then placed in alphabetical
               order and comma separated.  For example:

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

               At this time refer(1) style references are not accommodated.

     .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 C'') 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, if need be, should be placed here.

     .Sh CAVEATS
               Explanations of common misuses, e.g. security considerations
               for certain library functions.

     .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

     .Ss     The `.Ss' macro begins a subsection header, such as the one used
             for this subsection.  The `.Ss' macro can take up to nine argu-
             ments.  The `.Ss' macro is neither parsed nor callable.

   Paragraphs and Line Spacing.

     .Pp     The `.Pp' paragraph command may be used to specify a line space
             where necessary.  The macro is not necessary before or after
             `.Sh' macros, before or after a `.Ss' macro, or before a `.Bl' or
             `.Bd' macro.  (The `.Bl' and `.Bd' macros assert a vertical dis-
             tance unless the -compact flag is given).

   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 is -words and 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(1) from placing the flag and
     the argument on separate lines.  (Actually, the option macro used to pre-
     vent this from occurring, but was dropped when the decision (religious)
     was made to force right justified margins in troff(1) as options in gen-
     eral look atrocious when spread across a sparse line.  More work needs to
     be done with the keep macros; a -line option needs to be added.)

   Examples and Displays
     There are six types of displays: a quickie, one-line indented display
     `.D1'; a quickie one-line literal display `.Dl'; and block-ragged, block-
     unfilled, block-filled, and block-literal displays, which use the `.Bd'
     begin-display and `.Ed' end-display macros.

     .D1    (D-one) Display one line of indented text.  The `.D1' macro is
            parsed, but is not callable.

                  -ldghfstru

            The above was produced by: .Dl Fl ldghfstru.

     .Dl    (D-ell) Display one line of indented literal text.  The `.Dl' ex-
            ample macro has been used throughout this file.  It allows the in-
            dent (display) of one line of text.  Its default font is set to
            constant width (literal).  The `.Dl' macro is parsed, but is 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 end with the `.Ed' macro.
            Displays may be nested within lists, but may not contain other
            displays; this also prohibits nesting of `.D1' and `.Dl' one-line
            displays.  `.Bd' has the following syntax:

                  .Bd display-type [-offset offset_value] [-compact]

            The display-type must be one of the following four types and may
            have an offset specifier for indentation:

            -ragged           Fill, but do not adjust the right margin.
            -unfilled         Do not fill.  Display a block of text as typed.
                              The right (and left) margin edges are left
                              ragged.
            -filled           Display a filled (formatted) block.  The block
                              of text is formatted (the edges are filled, not
                              left unjustified).
            -literal          Display a literal block, useful for source code
                              or simple tabbed or spaced text.
            -file file_name   The file name following the -file flag is read
                              and displayed.  Literal mode is asserted and
                              tabs are set at 8 constant width character in-
                              tervals, however any troff(1)/-mdoc commands in
                              file will be processed.
            -offset string    If -offset is specified with one of the follow-
                              ing strings, the string is interpreted to indi-
                              cate the level of indentation for the forthcom-
                              ing 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      Indents by one default indent value
                                          or tab.  The default indent value is
                                          also used for the `.D1' display so
                                          one is guaranteed the two types of
                                          displays will line up.  This indent
                                          is normally set to 6n or about two
                                          thirds of an inch (six constant
                                          width characters).
                              indent-two  Indents 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
                                          by troff(1).

     .Ed    End-display.

   Tagged 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 other than
     -enum 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 al-
     lowed or disallowed).  Most of this document has been formatted with a
     tag style list (-tag).  For a change of pace, the list-type used to pre-
     sent the list-types is an over-hanging list (-ohang).  This type of list
     is quite popular with TeX users, but might look a bit funny after having
     read many pages of tagged lists.  The following list types are accepted
     by `.Bl':

     -bullet, -dash, -enum, -hyphen, -item
     These five are the simplest types of lists.  Once the `.Bl' macro has
     been given, items in the list are merely indicated by a line consisting
     solely of the `.It' macro.

     Examples of the different types:

     -bullet   A bullet list.

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

     Produces:
                 o   Bullet one goes here.
                 o   Bullet two here.

     -dash   A dash (or -hyphen) list.

                 .Bl -dash -compact
                 .It
                 Item one goes here.
                 .It
                 Item two here.
                 .El

     Produces:
                 -   Item one goes here.
                 -   Item two here.

     -enum   An enumerated list.

                 .Bl -enum -compact
                 .It
                 Item one goes here.
                 .It
                 And item two here.
                 .It
                 Lastly item three goes here.
                 .El

     The results:

                 1.   Item one goes here.
                 2.   And item two here.
                 3.   Lastly item three goes here.

     -item   An item list.

                 .Bl -item -compact
                 .It
                 Item one goes here.
                 Item one goes here.
                 Item one goes here.
                 .It
                 Item two goes here.
                 Item two goes here.
                 Item two goes here.
                 .El

     Produces:
                 Item one goes here.  Item one goes here.  Item one goes here.
                 Item two goes here.  Item two goes here.  Item two goes here.

     -tag, -diag, -hang, -ohang, -inset
     These list types collect arguments specified with the `.It' macro and
     create a label which may be inset into the forthcoming text, hanged from
     the forthcoming text, overhanged from above and not indented or tagged.
     This list was constructed with the `-ohang' list-type.  The `.It' macro
     is parsed only for the inset, hang and tag list-types and is not
     callable.  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 at-
           tribute as described below.

           Diag Diag lists create section four diagnostic lists and are simi-
           lar 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
           .Nm -mdoc
           manuals to other formats.
           .El

     Here is a hanged list with just two items:

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

           Longer hanged list labels blend in to 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 in to the paragraph unlike
           tagged paragraph labels.
           .El

     Here is an overhanged list:

           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.

     And the unformatted text which created it:

           .Bl -ohang
           .It Sy SL
           Sleep time of the process.
           .It Sy PAGEIN
           Number of disk I/O's resulting from references by the process
           to pages not in core.
           .El

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

           .Bl -diag
           .It "xl%d: couldn't map memory"
           A fatal initialization error has occurred.
           .It "xl%d: couldn't map interrupt"
           A fatal initialization error has occurred.
           .El

     produces:

     xl%d: couldn't map memory  A fatal initialization error has occurred.

     xl%d: couldn't map interrupt  A fatal initialization error has occurred.

     The tagged list which follows uses a width specifier to control the width
     of the tag.

           SL      sleep time of the process (seconds blocked)
           PAGEIN  number of disk I/O's resulting from references by the pro-
                   cess 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 "PAGEIN" -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

     Acceptable width specifiers:

           -width Fl     sets the width to the default width for a flag.  All
                         callable macros have a default width value.  The
                         `.Fl', value is presently set to ten constant width
                         characters or about five-sixths of an inch.

           -width 24n    sets the width to 24 constant width characters or
                         about two inches.  The `n' is absolutely necessary
                         for the scaling to work correctly.

           -width ENAMETOOLONG
                         sets width to the constant width length of the string
                         given.

           -width "int mkfifo"
                         again, the width is set to the constant width of the
                         string given.

     If a width is not specified for the tag list type, the first 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 as if the macro name had been supplied as the width.
     However, if another item in the list is given with a different callable
     macro name, a new and nested list is assumed.  This effectively means
     that -width is required for the tag list type.

     -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.
     Each `.It' argument is parsed to make a row and 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 "String" "Nroff" "Troff" -offset indent
           .It Sy "String" Ta Sy "Nroff" Ta Sy "Troff"
           .It Li "<=" Ta \&<\&= Ta \*(<=
           .It Li ">=" Ta \&>\&= Ta \*(>=
           .El

PREDEFINED STRINGS
     The following strings are predefined and may be used by preceding them
     with the troff(1) string interpreting sequence `\*(xx' where xx is the
     name of the defined string or as `\*x' where x is the name of the string.
     The interpreting sequence may be used anywhere in the text.

           String     Nroff     Troff
           <=         <=        <=
           >=         >=        >=
           Rq         ''        ''
           Lq         ``        ``
           ua         ^         ^
           aa         '
           ga         `         `
           q          "         "
           Pi         pi        pi
           Ne         !=        !=
           Le         <=        <=
           Ge         >=        >=
           Lt         <         <
           Gt         >         >
           Pm         +-        +-
           If         infinity  Infinity
           Na         NaN       NaN
           Ba         |         |

DIAGNOSTICS
     The debugging facilities for -mdoc are limited, but can help detect sub-
     tle errors such as the collision of an argument name with an internal
     register or macro name.  (A what?)  A register is an arithmetic storage
     class for troff(1) with a one or two-character name.  All registers in-
     ternal to -mdoc for troff(1) and ditroff are two characters and of the
     form <upper_case><lower_case> such as `Ar', <lower_case><upper_case> as
     `aR' or <upper or lower letter><digit> as `C1'.  And adding to the mud-
     dle, troff has its own internal registers all of which are either two
     lower case characters or a dot plus a letter or meta-character character.
     In one of the introduction examples, it was shown how to prevent the in-
     terpretation of a macro name with the escape sequence `\&'.  This is suf-
     ficient for the internal register names also.

     If a non-escaped register name is given in the argument list of a re-
     quest, unpredictable behavior will occur.  In general, any time huge por-
     tions of text do not appear where expected in the output, or small
     strings such as list tags disappear, chances are there is a misunder-
     standing about an argument type in the argument list.  Your mother never
     intended for you to remember this evil stuff - so here is a way to find
     out whether or not your arguments are valid: The `.Db' (debug) macro dis-
     plays the interpretation of the argument list for most macros.  Macros
     such as the `.Pp' (paragraph) macro do not contain debugging information.
     All of the callable macros do, and it is strongly advised whenever in
     doubt, turn on the `.Db' macro.

           Usage: .Db [on | off]

     An example of a portion of text with the debug macro placed above and be-
     low an artificially created problem (a flag argument `aC' which should be
     `\&aC' in order to work):

           .Db on
           .Op Fl aC Ar file )
           .Db off

     The resulting output:

           DEBUGGING ON
           DEBUG(argv) MACRO: `.Op'  Line #: 2
                   Argc: 1  Argv: `Fl'  Length: 2
                   Space: `'  Class: Executable
                   Argc: 2  Argv: `aC'  Length: 2
                   Space: `'  Class: Executable
                   Argc: 3  Argv: `Ar'  Length: 2
                   Space: `'  Class: Executable
                   Argc: 4  Argv: `file'  Length: 4
                   Space: ` '  Class: String
                   Argc: 5  Argv: `)'  Length: 1
                   Space: ` '  Class: Closing Punctuation or suffix
                   MACRO REQUEST: .Op Fl aC Ar file )
           DEBUGGING OFF

     The first line of information tells the name of the calling macro, here
     `.Op', and the line number it appears on.  If one or more files are in-
     volved (especially if text from another file is included) the line number
     may be bogus.  If there is only one file, it should be accurate.  The
     second line gives the argument count, the argument (Fl) and its length.
     If the length of an argument is two characters, the argument is tested to
     see if it is executable (unfortunately, any register which contains a
     non-zero value appears executable).  The third line gives the space al-
     lotted for a class, and the class type.  The problem here is the argument
     `aC' should not be executable.  The four types of classes are string, ex-
     ecutable, closing punctuation and opening punctuation.  The last line
     shows the entire argument list as it was read.  In this next example, the
     offending `aC' is escaped:

           .Db on
           .Em An escaped \&aC
           .Db off

           DEBUGGING ON
           DEBUG(fargv) MACRO: `.Em'  Line #: 2
                   Argc: 1  Argv: `An'  Length: 2
                   Space: ` '  Class: String
                   Argc: 2  Argv: `escaped'  Length: 7
                   Space: ` '  Class: String
                   Argc: 3  Argv: `aC'  Length: 2
                   Space: ` '  Class: String
                   MACRO REQUEST: .Em An escaped &aC
           DEBUGGING OFF

     The argument `\&aC' shows up with the same length of 2 as the `\&' se-
     quence produces a zero width, but a register named `\&aC' was not found
     and the type classified as string.

     Other diagnostics consist of usage statements and are self explanatory.

GROFF, TROFF AND NROFF
     The -mdoc package does not need compatibility mode with groff(1).

     The package inhibits page breaks, and the headers and footers which nor-
     mally occur at those breaks with nroff(1), to make the manual more effi-
     cient for viewing on-line.  At the moment, groff(1) with -Tascii does
     eject the imaginary remainder of the page at end of file.  The inhibiting
     of the page breaks makes nroff(1)'d files unsuitable for hardcopy.  There
     is a register named `cR' which can be set to zero in the site dependent
     style file /usr/share/tmac/mdoc/doc-nroff to restore the old style behav-
     ior.

FILES
     tmac.doc                       manual macro package
     tmac.doc-common                common structural macros and definitions
     tmac.doc-ditroff               site dependent troff(1) style file
     tmac.doc-nroff                 site dependent nroff(1) style file
     tmac.doc-syms                  special defines
     /usr/share/misc/mdoc.template  template for writing a man page

SEE ALSO
     groff(1), man(1), nroff(1), troff(1), mdoc(7)

BUGS
     Undesirable hyphenation on the dash of a macro argument is not yet re-
     solved, and can cause line break on the hyphen.

     A `.Pp' before a display causes a double vertical space in PostScript
     output.

     No macro yet exists to cause a line break without inserting a vertical
     space (such as troff's `.br' macro).

     `.Dt' does not allow arbitrary arguments, and certainly should.

     Arbitrary arguments to `.Os' must be double quoted.

     The `.At' macro cannot handle punctuation.

     `.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.

     If the outer-most list definition does not have a -width argument, the
     `.It' elements of inner lists may not work (producing a list where each
     successive element ``walks'' to the right).

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

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

OpenBSD 4.7                    February 18, 2010                            29
