Provided by: manpages_4.04-2_all bug

NAME

     mdoc.samples — tutorial sampler for writing BSD manuals with -mdoc

SYNOPSIS

     man mdoc.samples

DESCRIPTION

     A tutorial sampler for writing BSD manual pages with the -mdoc macro package, a
     content-based and domain-based formatting package for troff(1).  Its predecessor, the
     -man(7) package, addressed page layout leaving the manipulation of fonts and other
     typesetting details to the individual author.  In -mdoc, page layout macros make up the page
     structure domain which consists of macros for titles, section headers, displays and lists.
     Essentially items which affect the physical position of text on a formatted page.  In
     addition to the page structure domain, there are two more domains, the manual domain and the
     general text domain.  The general text domain is defined as macros which perform tasks such
     as quoting or emphasizing pieces of text.  The manual domain is defined as macros that are a
     subset of the day to day informal language used to describe commands, routines and related
     BSD 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 remained 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.

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

           3.   TITLE MACROS.

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

           5.   MANUAL DOMAIN
                      Addresses.
                      Author name.
                      Arguments.
                      Configuration Declarations (section four only).
                      Command Modifier.
                      Defined Variables.
                      Errno's (Section two only).
                      Environment Variables.
                      Function Argument.
                      Function Declaration.
                      Flags.
                      Functions (library routines).
                      Function Types.
                      Interactive Commands.
                      Names.
                      Options.
                      Pathnames.
                      Variables.
                      Cross References.

           6.   GENERAL TEXT DOMAIN
                      AT&T Macro.
                      BSD Macro.
                      FreeBSD Macro.
                      UNIX Macro.
                      Enclosure/Quoting Macros
                                  Angle Bracket Quote/Enclosure.
                                  Bracket Quotes/Enclosure.
                                  Double Quote macro/Enclosure.
                                  Parenthesis Quote/Enclosure.
                                  Single Quotes/Enclosure.
                                  Prefix Macro.
                      No-Op or Normal Text Macro.
                      No Space Macro.
                      Section Cross References.
                      References and Citations.
                      Return Values (sections two and three only)
                      Trade Names (Acronyms and Type Names).
                      Extended  Arguments.

           7.   PAGE STRUCTURE DOMAIN
                      Section Headers.
                      Paragraphs and Line Spacing.
                      Keeps.
                      Displays.
                      Font Modes (Emphasis, Literal, and Symbolic).
                      Lists and Columns.

           8.   PREDEFINED STRINGS

           9.   DIAGNOSTICS

           10.  FORMATTING WITH GROFF, TROFF AND NROFF

           11.  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 Extensions).  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, ‘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 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.  It is not expensive for groff
     but for the sake of portability, has been limited to the following macros which need it the
     most:

           Cd    Configuration declaration (section 4 SYNOPSIS)
           Bl    Begin list (for the width specifier).
           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.
     For example:

           fetch(char *str)  is created by ‘.Fn fetch char\ *str’

           fetch(char *str)  can also be created by ‘.Fn fetch "char *str"’

     If the ‘\’ 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.

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.  Several example man pages can also be found in
     /usr/share/examples/mdoc.

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

     The first items in the template are the macros (.Dd, .Os, .Dt); the document date, the
     operating system the man page or subject source is developed or modified for, and the man
     page title (in uppercase) along with the section of the manual the page belongs in.  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 authorship.  These macros are one called once at the very beginning of the document and
     are used to construct the headers and footers only.

     .Dt DOCUMENT_TITLE section# [volume]
             The document title is the subject of the man page and must be in CAPITALS due to
             troff limitations.  The section number may be 1, ..., 8, and if it is specified, the
             volume title may be omitted.  A volume title may be arbitrary or one of the
             following:

                   AMD    UNIX Ancestral Manual Documents
                   SMM    UNIX System Manager's Manual
                   URM    UNIX Reference Manual
                   PRM    UNIX Programmer's Manual

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

     .Os operating_system release#
             The name of the operating system should be the common acronym, for example, BSD or
             FreeBSD or ATT.  The release should be the standard release nomenclature for the
             system specified, for example, 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 4.3BSD

             or
                   .Os FreeBSD 2.2

             or for a locally produced set

                   .Os CS Department

             The Berkeley default, ‘.Os’ without an argument, has been defined as BSD 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.

     .Dd month day, year
             The date should be written formally:

                   January 25, 1989

INTRODUCTION OF MANUAL AND GENERAL TEXT DOMAINS

   What's in a name...
     The manual domain macro names are derived from the day to day informal language used to
     describe commands, subroutines and related files.  Slightly different variations of this
     language are used to describe the three different aspects of writing a man page.  First,
     there is the description of -mdoc macro 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 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 ‘Ar’ argument macro is used for an operand or file argument
     like target as well as an argument to a flag like variable.  The make command line was
     produced from:

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

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

   General Syntax
     The manual domain and general text domain macros share a similar syntax with a few minor
     deviations: ‘.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:

           .Li sptr, ptr),

     The result is:

           sptr, ptr),

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

           .Li sptr , ptr ) ,

     The result is:

           sptr, ptr),

     The punctuation is now recognized and is output in the default font distinguishing it from
     the strings in literal font.

     To remove the special meaning from a punctuation character escape it with ‘\&’.  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 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.  ‘.Ad’ is callable by other macros and is
     parsed.

   Author Name
     The ‘.An’ macro is used to specify the name of the author of the item being documented, or
     the name of the author of the actual manual page.  Any remaining arguments after the name
     information are assumed to be punctuation.

           Usage: .An author_name [.,:;()[]?!]
                   .An Joe Author        Joe Author
                   .An Joe Author ,      Joe Author,
                   .An Joe Author Aq nobody@FreeBSD.ORG
                                         Joe Author <nobody@FreeBSD.ORG>
                   .An Joe Author ) ) ,  Joe Author)),

     The ‘.An’ macro is parsed and is callable.  It is an error to call ‘.An’ without any
     arguments.

   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, ‘Ar’ is assumed.  The ‘.Ar’ macro is parsed and is
     callable.

   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?’.

   Command Modifier
     The command modifier is identical to the ‘.Fl’ (flag) command with the exception 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.

   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.  ‘.Dv’ is parsed and is callable.

   Errno's (Section two only)
     The ‘.Er’ errno macro specifies the error return value for section two library routines.
     The second example below shows ‘.Er’ used with the ‘.Bq’ general text domain macro, as it
     would be used in a section two manual page.

           Usage: .Er 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.

   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.

   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.  ‘.Fa’ is parsed and is callable.

   Function Declaration
     The ‘.Fd’ macro is used in the SYNOPSIS section with section two or three functions.  The
     ‘.Fd’ macro does not call other macros and is not callable by other macros.

           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.

   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:

           .Fo "int 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 line lengths and may
     split across a newline ungracefully.  This will be fixed in the near future.

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

           Usage: .Ft type ... [.,:;()[]?!]
                   .Ft struct stat  struct stat

     The ‘.Ft’ request is not callable by other macros.

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

           Usage: .Ic argument ... [.,:;()[]?!]
                   .Ic :wq                  :wq
                   .Ic do while {...}       do while {...}
                   .Ic setenv , unsetenv    setenv, unsetenv

     It is an error to call ‘.Ic’ without arguments.  The ‘.Ic’ 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.  Note: a section two or three document
     function name is addressed with the ‘.Nm’ in the NAME section, and with ‘.Fn’ in the
     SYNOPSIS and remaining sections.  For interactive commands, such as the ‘while’ command
     keyword in csh(1), the ‘.Ic’ macro should be used.  While the ‘.Ic’ is nearly identical to
     ‘.Nm’, it can not recall the first argument it was invoked with.

           Usage: .Nm argument ... [.,:;()[]?!]
                   .Nm mdoc.sample  mdoc.sample
                   .Nm \-mdoc       -mdoc.
                   .Nm foo ) ) ,    foo)),
                   .Nm              mdoc.samples

     The ‘.Nm’ macro is parsed and is callable.

   Options
     The ‘.Op’ macro places option brackets around the 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 pathnames or filenames.

           Usage: .Pa pathname [.,:;()[]?!]
                   .Pa /usr/share         /usr/share
                   .Pa /tmp/fooXXXXX ) .  /tmp/fooXXXXX).

     The ‘.Pa’ 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 page number or punctuation.  Any remaining
     arguments are assumed to be punctuation.

           Usage: .Xr man_page [1,...,8] [.,:;()[]?!]
                   .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 [v6 | v7 | 32v | V.1 | V.4] ... [ .,:;()[]?! ]
                   .At         AT&T UNIX
                   .At v6 .    Version 6 AT&T UNIX.

     The ‘.At’ macro is not parsed and not callable It accepts at most two arguments.

   BSD Macro
           Usage: .Bx [Version/release] ... [.,:;()[]?!]
                   .Bx          BSD
                   .Bx 4.3 .    4.3BSD.

     The ‘.Bx’ macro is parsed and is callable.

   FreeBSD Macro
           Usage: .Fx Version.release ... [ .,:;()[]?! ]
                   .Fx 2.2 .    FreeBSD 2.2.

     The ‘.Fx’ macro is not parsed and not callable It accepts at most two arguments.

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

     The ‘.Ux’ macro is parsed and is callable.

   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.

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

     .Ql       The quoted literal macro behaves differently for troff than nroff.  If formatted
               with nroff, a quoted literal is always quoted.  If formatted with troff, an item
               is quoted only 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.

     .Pf       The prefix macro is not callable, but it is parsed:

                     .Pf ( Fa name2
                              becomes (name2.

               The ‘.Ns’ (no space) macro performs the analogous suffix function.

     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.

   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.

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

                   .Sx FILES     FILES

   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 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.
           .%C     City/place.
           .%D     Date.
           .%J     Journal name.
           .%N     Issue number.
           .%O     Optional information.
           .%P     Page number.
           .%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/ditroff output.

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

           Usage: .Rv [-std function]

     ‘.Rv -std atexit’ will generate the following text:

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

     The -std option is valid only for manual page sections 2 and 3.

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

           Usage: .Tn symbol ... [.,:;()[]?!]
                   .Tn DEC    DEC
                   .Tn ASCII  ASCII

     The ‘.Tn’ macro is parsed and is callable by other macros.

   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 a 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.  Out of 900 manual pages (about 1500 actual pages) currently released with BSD
     only fifteen use the ‘.Xo’ macro.

PAGE STRUCTURE DOMAIN

   Section Headers
     The first three ‘.Sh’ section header macros list 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.  It is parsed and but is not 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 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 | Fl 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 ENVIRONMENT
               The ENVIRONMENT section should reveal any related environment variables and clues
               to their behavior and/or usage.

     .Sh EXAMPLES
               There are several ways to create examples.  See the EXAMPLES section below for
               details.

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

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

     .Sh AUTHORS
               Credits, if need be, should be placed here.

     .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
               and 3) should go here.  The ‘.Er’ macro is used to specify an errno.

     .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

   Paragraphs and Line Spacing.
     .Pp     The ‘.Pp’ paragraph command may be used to specify a line space where necessary.
             The macro is not necessary after a ‘.Sh’ or ‘.Ss’ macro or before a ‘.Bl’ macro.
             (The ‘.Bl’ macro asserts 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 from placing up 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 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 five types of displays, a quickie one line indented display ‘.D1’, a quickie one
     line literal display ‘.Dl’, and a block literal, block filled and block ragged which use the
     ‘.Bd’ begin-display and ‘.Ed’ end-display macros.

     .D1    (D-one) Display one line of indented text.  This macro is parsed, but it 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) however it is parsed and will
            recognized other macros.  It is not callable however.

                  % ls -ldg /usr/local/bin

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

     .Bd    Begin-display.  The ‘.Bd’ display must be ended with the ‘.Ed’ macro.  Displays may
            be nested within displays and lists.  ‘.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: ‘.Bd’.

     -ragged           Display a block of text as typed, 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 filename 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/-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.
     .Ed               End-display.

   Font Modes
     There are five macros for changing the appearance of the manual page text:

     .Em    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.

     .Li    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.

     .Sy    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.

     .Bf    Begin font mode.  The ‘.Bf’ font mode must be ended with the ‘.Ef’ macro.  Font modes
            may be nested within other font modes.  ‘.Bf’ has the following syntax:

                  .Bf font-mode

            The font-mode must be one of the following three types: ‘.Bf’.

            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.

     .Ef    End font mode.

   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 may be nested within themselves and within displays.  Columns may be
     used inside of lists, but lists are unproven inside of columns.

     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
     -item
     -enum
     These three 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.  For example,
     the source text for a simple enumerated list would look like:

                 .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.

     A simple bullet list construction:

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

     Produces:
               ·   Bullet one goes here.
               ·   Bullet two 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 ‘Fl 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.

           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 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

     The tagged list which follows uses an optional 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 process priority (nonpositive when in
                   noninterruptible 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 process priority
           (nonpositive when in noninterruptible 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 sixth 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.

PREDEFINED STRINGS

     The following strings are predefined as may be used by preceding with the troff 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 any where in the text.

           String     Nroff     Troff
           <=         <=        ≤
           >=         >=        ≥
           Rq         ''        ”
           Lq         ``        “
           ua         ^         ↑
           aa         '         ´
           ga         `         `
           q          "         "
           Pi         pi        π
           Ne         !=        ≠
           Le         <=        ≤
           Ge         >=        ≥
           Lt         <         >
           Gt         >         <
           Pm         +-        ±
           If         infinity  ∞
           Na         NaN       NaN
           Ba         |         |

     Note: The string named ‘q’ should be written as ‘\*q’ since it is only one char.

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 with a one or two character name.  All
     registers internal to -mdoc for troff 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 muddle, troff has its own internal registers all
     of which are either two lowercase characters or a dot plus a letter or metacharacter
     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 nonescaped 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 (‘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 nonzero 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.

     The package inhibits page breaks, and the headers and footers which normally occur at those
     breaks with nroff, to make the manual more efficient for viewing on-line.  At the moment,
     groff with -Tascii does eject the imaginary remainder of the page at end of file.  The
     inhibiting of the page breaks makes nroff'd files unsuitable for hardcopy.  There is a
     register named ‘cR’ which can be set to zero in the site dependent style file
     /usr/src/share/tmac/doc-nroff to restore the old style behavior.

FILES

     /usr/share/tmac/doc.tmac      manual macro package
     /usr/share/misc/mdoc.template
                                   template for writing a man page
     /usr/share/examples/mdoc/*    several example man pages

BUGS

     Undesirable hyphenation on the dash of a flag argument is not yet resolved, and causes
     occasional mishaps in the DESCRIPTION section.  (line break on the hyphen).

     Predefined strings are not declared in documentation.

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

     ‘.Nm’ font should be changed in NAME section.

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

     The method used to prevent header and footer page breaks (other than the initial header and
     footer) when using nroff occasionally places an unsightly partially filled line (blank) at
     the would be bottom of the page.

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

SEE ALSO

     man(1), troff(1), groff_mdoc(7), mdoc(7)

COLOPHON

     This page is part of release 4.04 of the Linux man-pages project.  A description of the
     project, information about reporting bugs, and the latest version of this page, can be found
     at http://www.kernel.org/doc/man-pages/.