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 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 OpenBSD 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. It is hoped 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
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 character 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 arguments 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 special 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 executed or called when it is processed. In this case the argument, although 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, ‘-’ and ‘file ...’, to specify an optional flag with an argument:

[-s bytes]
    is produced by .Op -s bytes

To prevent a two-character string from being interpreted as a macro name, precede the string with the escape sequence ‘\&’:

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

Here the strings ‘-’ and ‘file ...’ 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 reference 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 embedded 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 implement 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 following macros which need it the most:

Bl  Begin list (for the width specifier).
    Configuration declaration (section 4 SYNOPSIS).
    Emphasized text.
    Functions (sections two and four).
It  List items.
    Literal text.
    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 replacing 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 hyphen 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 document 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 volume title. This is useful for pages specific only to a particular architecture. The architectures currently defined are:

        alpha, amd64, amiga, arc, armish, aviion, hp300,
        hppa, hppa64, i386, landisk, loongson, luna88k,
        mac68k, macppc, mips64, mvme68k, mvme88k, 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 description 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 confusion; however, the -mdoc package does not have a macro for an argument to a flag. Instead the ‘file ...’ 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 punctuation, 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 distinguishing it from the argument strings. To remove the special meaning from a punctuation character escape it with ‘\&’. The following punctuation 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 quotation set:

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

The problem is that troff(1) may assume it is supposed to actually perform the operation or evaluation suggested by the characters. To prevent the accidental evaluation of these characters, escape them with ‘\&’. Typical syntax is shown in the first content macro displayed below, ‘.Ad’.

MANUAL DOMAIN

  Address Macro
The address macro identifies an address construct of the form addr1[,addr2[,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 author 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 device interface in a section four manual. This macro accepts quoted arguments (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 neither 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 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 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)

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) outside 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 declaration 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
    <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 declaration for the include file.

  Literals
The ‘.Li’ literal macro may be used for special characters, variable constants, 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 identical 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 brackets. 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 value -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
    p1003.1-88
-p1003.1-90
    p1003.1-90
-p1003.1-96
    p1003.1-96
-p1003.1-2001
    p1003.1-2001
-p1003.1-2004
    p1003.1-2004
-p1003.1-2008
    p1003.1-2008
-p1003.1
    p1003.1
-p1003.1b
    p1003.1b
-p1003.1b-93
    p1003.1b-93
-p1003.1c-95
    p1003.1c-95
-p1003.1g-2000
    p1003.1g-2000
-p1003.2-92
    p1003.2-92
-p1387.2-95
    p1387.2-95
-p1003.2
    p1003.2
-p1387.2
    p1387.2
-isoC-90
    isoC-90
-isoC-amd1
    isoC-amd1
-isoC-tcor1
    isoC-tcor1
-isoC-tcor2
    isoC-tcor2
-isoC-99
    isoC-99
-ansiC
    ansiC
-ansiC-89
    ansiC-89
-ansiC-99
    ansiC-99
-ieee754
    ieee754
-iso8802-3
    iso8802-3
-xpg3
    xpg3
-xpg4
    xpg4
-xpg4.2
    xpg4.2
-xpg4.3
    xpg4.3
-xbd5
    xbd5
-xcu5
    xcu5
-xsh5
    xsh5
-xns5
    xns5
-xns5.2d2.0
    xns5.2d2.0
-xcurses4.2
    xcurses4.2
-susv2
    susv2
-susv3
    susv3
-svid4
    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 punctuation. 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
    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
    BSD/OS
.Bsx 3.0 .
    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 arguments). Font modes may be nested within other font modes.

    Usage: .Bf font mode

Font mode must be one of the following:

| -emphasis
    Same as if the ‘.Em’ macro was used for the entire block of text.
| -literal
    Same as if the ‘.Li’ macro was used for the entire block of text.
| -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 enclose one or more strings between a pair of characters like quotes or parentheses. The terms quoting and enclosure are used interchangeably throughout this document. Most of the one line enclosure macros end in small letter ‘q’ to give a hint of quoting, but there are a few irregularities. For each enclosure macro there is 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 quoting 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 always quoted. If formatted with troff(1), 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.

Examples of quoting:
.Aq <>
.Aq ctype.h ) ,
    <ctype.h>),
.Bq []
.Bq 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.

  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 situations 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, respectively.

    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 predictably 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 often, 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 possible, 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’ 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 -benstuv
        .Op -
        .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, 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).

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 p1003.2 or ansiC 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 arguments. 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 distance 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 prevent this from occurring, but was dropped when the decision (religious) was made to force right justified margins in troff(1) as options in general 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 -ldghfstru.

.Dl (D-ell) Display one line of indented literal text. The ‘.Dl’ example macro has been used throughout this file. It allows the indent (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 intervals, however any troff(1)/-mdoc commands in file will be processed.
    -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 margin. This is the default mode of ‘.Bd’.
        center
            Supposedly center the block. At this time, unfortunately, the block merely gets left aligned about an imaginary center margin.
        indent
            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 allowed 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 present 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:
•   Bullet one goes here.
•   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 attribute as described below.

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

Hang Hanged labels are a matter of taste.

Ohang Overhanging labels are nice when space is constrained.

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

Here is the source text which produced the above example:

    .Bl -inset -offset indent
    .It Em Tag
    The tagged list (also called a tagged paragraph) is the
    most common type of list used in the Berkeley manuals.
    .It Em Diag
    Diag lists create section four diagnostic lists
    and are similar to inset lists except callable
    macros are ignored.
    .It Em Hang
    Hanged labels are a matter of taste.
    .It Em Ohang
    Overhanging labels are nice when space is constrained.
    .It Em Inset
    Inset labels are useful for controlling blocks of
    paragraphs and are valuable for converting
    .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 meaningful 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 process to pages not loaded in core.
UID numerical user ID of process owner
PPID
    numerical ID of parent of process priority (non-positive when in non-interruptible wait)

The raw text:

    .Bl -tag -width "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 |
Ne | != |
Le | <= |
Ge | >= |
Lt | < |
Gt | > |
Pm | +- |
If | infinity |
Na | NaN |
Ba | | |

DIAGNOSTICS
The debugging facilities for -mdoc are limited, but can help detect subtle 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 internal to -mdoc for troff(1) and ditroff are two characters and of the form <upper_case><lower_case> such as ‘file ...’, <lower_case><upper_case> as ‘aR’ or <upper or lower letter><digit> as ‘C1’. And adding to the muddle, 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 interpretation of a macro name with the escape sequence ‘\&’. This is sufficient for the internal register names also.

If a non-escaped register name is given in the argument list of a request, unpredictable behavior will occur. In general, any time huge portions of text do not appear where expected in the output, or small strings such as list tags disappear, chances are there is a misunderstanding 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 displays 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 below 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 involved (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 (-) 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 allotted 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, executable, 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 ‘\&’ sequence 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 normally occur at those breaks with nroff(1), to make the manual more efficient 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 behavior.

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 resolved, 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.