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Diff for /mandoc/mandoc.1 between version 1.76 and 1.258

version 1.76, 2010/08/18 08:41:40 version 1.258, 2022/04/28 16:21:09
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 .\"     $Id$  .\" $Id$
 .\"  .\"
 .\" Copyright (c) 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>  .\" Copyright (c) 2012, 2014-2022 Ingo Schwarze <schwarze@openbsd.org>
   .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"  .\"
 .\" Permission to use, copy, modify, and distribute this software for any  .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above  .\" purpose with or without fee is hereby granted, provided that the above
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 .Os  .Os
 .Sh NAME  .Sh NAME
 .Nm mandoc  .Nm mandoc
 .Nd format and display UNIX manuals  .Nd format manual pages
 .Sh SYNOPSIS  .Sh SYNOPSIS
 .Nm mandoc  .Nm mandoc
 .Op Fl V  .Op Fl ac
 .Op Fl f Ns Ar option  .Op Fl I Cm os Ns = Ns Ar name
 .Op Fl m Ns Ar format  .Op Fl K Ar encoding
 .Op Fl O Ns Ar option  .Op Fl mdoc | man
 .Op Fl T Ns Ar output  .Op Fl O Ar options
 .Op Fl W Ns Ar err  .Op Fl T Ar output
 .Op Ar file...  .Op Fl W Ar level
   .Op Ar
 .Sh DESCRIPTION  .Sh DESCRIPTION
 The  The
 .Nm  .Nm
 utility formats  utility formats manual pages for display.
 .Ux  
 manual pages for display.  
 The arguments are as follows:  
 .Bl -tag -width Ds  
 .It Fl f Ns Ar option  
 Comma-separated compiler options.  
 See  
 .Sx Compiler Options  
 for details.  
 .It Fl m Ns Ar format  
 Input format.  
 See  
 .Sx Input Formats  
 for available formats.  
 Defaults to  
 .Fl m Ns Cm andoc .  
 .It Fl O Ns Ar option  
 Comma-separated output options.  
 .It Fl T Ns Ar output  
 Output format.  
 See  
 .Sx Output Formats  
 for available formats.  
 Defaults to  
 .Fl T Ns Cm ascii .  
 .It Fl V  
 Print version and exit.  
 .It Fl W Ns Ar err  
 Comma-separated warning options.  
 Use  
 .Fl W Ns Cm all  
 to print warnings,  
 .Fl W Ns Cm error  
 for warnings to be considered errors and cause utility  
 termination.  
 Multiple  
 .Fl W  
 arguments may be comma-separated, such as  
 .Fl W Ns Cm error , Ns Cm all .  
 .It Ar file  
 Read input from zero or more files.  
 If unspecified, reads from stdin.  
 If multiple files are specified,  
 .Nm  
 will halt with the first failed parse.  
 .El  
 .Pp  .Pp
 By default,  By default,
 .Nm  .Nm
Line 86  reads
Line 42  reads
 .Xr mdoc 7  .Xr mdoc 7
 or  or
 .Xr man 7  .Xr man 7
 text from stdin, implying  text from stdin and produces
 .Fl m Ns Cm andoc ,  .Fl T Cm locale
 and produces  
 .Fl T Ns Cm ascii  
 output.  output.
 .Pp  .Pp
 .Ex -std mandoc  The options are as follows:
 .Ss Input Formats  .Bl -tag -width Ds
 The  .It Fl a
 .Nm  If the standard output is a terminal device and
 utility accepts  .Fl c
   is not specified, use
   .Xr less 1
   to paginate the output, just like
   .Xr man 1
   would.
   .It Fl c
   Copy the formatted manual pages to the standard output without using
   .Xr less 1
   to paginate them.
   This is the default.
   It can be specified to override
   .Fl a .
   .It Fl I Cm os Ns = Ns Ar name
   Override the default operating system
   .Ar name
   for the
 .Xr mdoc 7  .Xr mdoc 7
 and  .Ic \&Os
   and for the
 .Xr man 7  .Xr man 7
 input with  .Ic \&TH
 .Fl m Ns Cm doc  macro.
   .It Fl K Ar encoding
   Specify the input encoding.
   The supported
   .Ar encoding
   arguments are
   .Cm us-ascii ,
   .Cm iso-8859-1 ,
 and  and
 .Fl m Ns Cm an ,  .Cm utf-8 .
 respectively.  If not specified, autodetection uses the first match in the following
 The  list:
 .Xr mdoc 7  .Bl -enum
 format is  .It
 .Em strongly  If the first three bytes of the input file are the UTF-8 byte order
 recommended;  mark (BOM, 0xefbbbf), input is interpreted as
 .Xr man 7  .Cm utf-8 .
 should only be used for legacy manuals.  .It
   If the first or second line of the input file matches the
   .Sy emacs
   mode line format
 .Pp  .Pp
 A third option,  .D1 .\e" -*- Oo ...; Oc coding: Ar encoding ; No -*-
 .Fl m Ns Cm andoc ,  .Pp
 which is also the default, determines encoding on-the-fly: if the first  then input is interpreted according to
 non-comment macro is  .Ar encoding .
 .Sq \&Dd  .It
   If the first non-ASCII byte in the file introduces a valid UTF-8
   sequence, input is interpreted as
   .Cm utf-8 .
   .It
   Otherwise, input is interpreted as
   .Cm iso-8859-1 .
   .El
   .It Fl mdoc | man
   With
   .Fl mdoc ,
   all input files are interpreted as
   .Xr mdoc 7 .
   With
   .Fl man ,
   all input files are interpreted as
   .Xr man 7 .
   By default, the input language is automatically detected for each file:
   if the first macro is
   .Ic \&Dd
 or  or
 .Sq \&Dt ,  .Ic \&Dt ,
 the  the
 .Xr mdoc 7  .Xr mdoc 7
 parser is used; otherwise, the  parser is used; otherwise, the
 .Xr man 7  .Xr man 7
 parser is used.  parser is used.
   With other arguments,
   .Fl m
   is silently ignored.
   .It Fl O Ar options
   Comma-separated output options.
   See the descriptions of the individual output formats for supported
   .Ar options .
   .It Fl T Ar output
   Select the output format.
   Supported values for the
   .Ar output
   argument are
   .Cm ascii ,
   .Cm html ,
   the default of
   .Cm locale ,
   .Cm man ,
   .Cm markdown ,
   .Cm pdf ,
   .Cm ps ,
   .Cm tree ,
   and
   .Cm utf8 .
 .Pp  .Pp
 If multiple  The special
 files are specified with  .Fl T Cm lint
 .Fl m Ns Cm andoc ,  mode only parses the input and produces no output.
 each has its file-type determined this way.  It implies
 If multiple files are  .Fl W Cm all
 specified and  and redirects parser messages, which usually appear on standard
 .Fl m Ns Cm doc  error output, to standard output.
   .It Fl W Ar level
   Specify the minimum message
   .Ar level
   to be reported on the standard error output and to affect the exit status.
   The
   .Ar level
   can be
   .Cm base ,
   .Cm style ,
   .Cm warning ,
   .Cm error ,
 or  or
 .Fl m Ns Cm an  .Cm unsupp .
 is specified, then this format is used exclusively.  
 .Ss Compiler Options  
 Default  
 .Xr mdoc 7  
 and  
 .Xr man 7  
 compilation behaviour may be overridden with the  
 .Fl f  
 flag.  
 .Bl -tag -width Ds  
 .It Fl f Ns Cm ign-errors  
 When parsing multiple files, don't halt when one errors out.  
 Useful with  
 .Fl T Ns Cm lint  
 over a large set of manuals passed on the command line.  
 .It Fl f Ns Cm ign-escape  
 Ignore invalid escape sequences.  
 This is the default, but the option can be used to override an earlier  
 .Fl f Ns Cm strict .  
 .It Fl f Ns Cm ign-scope  
 When rewinding the scope of a block macro, forces the compiler to ignore  
 scope violations.  
 This can seriously mangle the resulting tree.  
 .Pq mdoc only  
 .It Fl f Ns Cm no-ign-escape  
 Do not ignore invalid escape sequences.  
 .It Fl f Ns Cm no-ign-macro  
 Do not ignore unknown macros at the start of input lines.  
 .It Fl f Ns Cm strict  
 Implies  
 .Fl f Ns Cm no-ign-escape  
 and  
 .Fl f Ns Cm no-ign-macro .  
 .El  
 .Ss Output Formats  
 The  The
   .Cm base
   level automatically derives the operating system from the contents of the
   .Ic \&Os
   macro, from the
   .Fl Ios
   command line option, or from the
   .Xr uname 3
   return value.
   The levels
   .Cm openbsd
   and
   .Cm netbsd
   are variants of
   .Cm base
   that bypass autodetection and request validation of base system
   conventions for a particular operating system.
   The level
   .Cm all
   is an alias for
   .Cm base .
   By default,
 .Nm  .Nm
 utility accepts the following  is silent.
 .Fl T  
 arguments, which correspond to output modes:  
 .Bl -tag -width Ds  
 .It Fl T Ns Cm ascii  
 Produce 7-bit ASCII output, backspace-encoded for bold and underline  
 styles.  
 This is the default.  
 See  See
 .Sx ASCII Output .  .Sx EXIT STATUS
 .It Fl T Ns Cm html  
 Produce strict HTML-4.01 output, with a sane default style.  
 See  
 .Sx HTML Output .  
 .It Fl T Ns Cm lint  
 Parse only: produce no output.  
 Implies  
 .Fl W Ns Cm all  
 and  and
 .Fl f Ns Cm strict .  .Sx DIAGNOSTICS
 .It Fl T Ns Cm pdf  for details.
 Produce PDF output.  .Pp
 See  The special option
 .Sx PDF Output .  .Fl W Cm stop
 .It Fl T Ns Cm ps  tells
 Produce PostScript output.  .Nm
 See  to exit after parsing a file that causes warnings or errors of at least
 .Sx PostScript Output .  the requested level.
 .It Fl T Ns Cm tree  No formatted output will be produced from that file.
 Produce an indented parse tree.  If both a
 .It Fl T Ns Cm xhtml  .Ar level
 Produce strict XHTML-1.0 output, with a sane default style.  and
 See  .Cm stop
 .Sx XHTML Output .  are requested, they can be joined with a comma, for example
   .Fl W Cm error , Ns Cm stop .
   .It Ar file
   Read from the given input file.
   If multiple files are specified, they are processed in the given order.
   If unspecified,
   .Nm
   reads from standard input.
 .El  .El
 .Pp  .Pp
 If multiple input files are specified, these will be processed by the  The options
 corresponding filter in-order.  .Fl fhklw
   are also supported and are documented in
   .Xr man 1 .
   In
   .Fl f
   and
   .Fl k
   mode,
   .Nm
   also supports the options
   .Fl CMmOSs
   described in the
   .Xr apropos 1
   manual.
   The options
   .Fl fkl
   are mutually exclusive and override each other.
 .Ss ASCII Output  .Ss ASCII Output
 Output produced by  Use
 .Fl T Ns Cm ascii ,  .Fl T Cm ascii
 which is the default, is rendered in standard 7-bit ASCII documented in  to force text output in 7-bit ASCII character encoding documented in the
 .Xr ascii 7 .  .Xr ascii 7
   manual page, ignoring the
   .Xr locale 1
   set in the environment.
 .Pp  .Pp
 Font styles are applied by using back-spaced encoding such that an  Font styles are applied by using back-spaced encoding such that an
 underlined character  underlined character
Line 226  where
Line 257  where
 is the back-space character number 8.  is the back-space character number 8.
 Emboldened characters are rendered as  Emboldened characters are rendered as
 .Sq c Ns \e[bs] Ns c .  .Sq c Ns \e[bs] Ns c .
   This markup is typically converted to appropriate terminal sequences by
   the pager or
   .Xr ul 1 .
   To remove the markup, pipe the output to
   .Xr col 1
   .Fl b
   instead.
 .Pp  .Pp
 The special characters documented in  The special characters documented in
 .Xr mandoc_char 7  .Xr mandoc_char 7
 are rendered best-effort in an ASCII equivalent.  are rendered best-effort in an ASCII equivalent.
   In particular, opening and closing
   .Sq single quotes
   are represented as characters number 0x60 and 0x27, respectively,
   which agrees with all ASCII standards from 1965 to the latest
   revision (2012) and which matches the traditional way in which
   .Xr roff 7
   formatters represent single quotes in ASCII output.
   This correct ASCII rendering may look strange with modern
   Unicode-compatible fonts because contrary to ASCII, Unicode uses
   the code point U+0060 for the grave accent only, never for an opening
   quote.
 .Pp  .Pp
 Output width is limited to 78 visible columns unless literal input lines  
 exceed this limit.  
 .Pp  
 The following  The following
 .Fl O  .Fl O
 arguments are accepted:  arguments are accepted:
 .Bl -tag -width Ds  .Bl -tag -width Ds
   .It Cm indent Ns = Ns Ar indent
   The left margin for normal text is set to
   .Ar indent
   blank characters instead of the default of five for
   .Xr mdoc 7
   and seven for
   .Xr man 7 .
   Increasing this is not recommended; it may result in degraded formatting,
   for example overfull lines or ugly line breaks.
   When output is to a pager on a terminal that is less than 66 columns
   wide, the default is reduced to three columns.
   .It Cm mdoc
   Format
   .Xr man 7
   input files in
   .Xr mdoc 7
   output style.
   This prints the operating system name rather than the page title
   on the right side of the footer line, and it implies
   .Fl O Cm indent Ns =5 .
   One useful application is for checking that
   .Fl T Cm man
   output formats in the same way as the
   .Xr mdoc 7
   source it was generated from.
   .It Cm tag Ns Op = Ns Ar term
   If the formatted manual page is opened in a pager,
   go to the definition of the
   .Ar term
   rather than showing the manual page from the beginning.
   If no
   .Ar term
   is specified, reuse the first command line argument that is not a
   .Ar section
   number.
   If that argument is in
   .Xr apropos 1
   .Ar key Ns = Ns Ar val
   format, only the
   .Ar val
   is used rather than the argument as a whole.
   This is useful for commands like
   .Ql man -akO tag Ic=ulimit
   to search for a keyword and jump right to its definition
   in the matching manual pages.
 .It Cm width Ns = Ns Ar width  .It Cm width Ns = Ns Ar width
 The output width is set to  The output width is set to
 .Ar width ,  .Ar width
 which will normalise to \(>=60.  instead of the default of 78.
   When output is to a pager on a terminal that is less than 79 columns
   wide, the default is reduced to one less than the terminal width.
   In any case, lines that are output in literal mode are never wrapped
   and may exceed the output width.
 .El  .El
 .Ss HTML Output  .Ss HTML Output
 Output produced by  Output produced by
 .Fl T Ns Cm html  .Fl T Cm html
 conforms to HTML-4.01 strict.  conforms to HTML5 using optional self-closing tags.
   Default styles use only CSS1.
   Equations rendered from
   .Xr eqn 7
   blocks use MathML.
 .Pp  .Pp
 Font styles and page structure are applied using CSS2.  The file
 By default, no font style is applied to any text,  .Pa /usr/share/misc/mandoc.css
 although CSS2 is hard-coded to format  documents style-sheet classes available for customising output.
 the basic structure of output.  If a style-sheet is not specified with
   .Fl O Cm style ,
   .Fl T Cm html
   defaults to simple output (via an embedded style-sheet)
   readable in any graphical or text-based web
   browser.
 .Pp  .Pp
 The  Non-ASCII characters are rendered
 .Pa example.style.css  as hexadecimal Unicode character references.
 file documents the range of styles applied to output and, if used, will  
 cause rendered documents to appear as they do in  
 .Fl T Ns Cm ascii .  
 .Pp  .Pp
 Special characters are rendered in decimal-encoded UTF-8.  
 .Pp  
 The following  The following
 .Fl O  .Fl O
 arguments are accepted:  arguments are accepted:
 .Bl -tag -width Ds  .Bl -tag -width Ds
   .It Cm fragment
   Omit the <!DOCTYPE> declaration and the <html>, <head>, and <body>
   elements and only emit the subtree below the <body> element.
   The
   .Cm style
   argument will be ignored.
   This is useful when embedding manual content within existing documents.
 .It Cm includes Ns = Ns Ar fmt  .It Cm includes Ns = Ns Ar fmt
 The string  The string
 .Ar fmt ,  .Ar fmt ,
 for example,  for example,
 .Ar ../src/%I.html ,  .Ar ../src/%I.html ,
 is used as a template for linked header files (usually via the  is used as a template for linked header files (usually via the
 .Sq \&In  .Ic \&In
 macro).  macro).
 Instances of  Instances of
 .Sq \&%I  .Sq \&%I
 are replaced with the include filename.  are replaced with the include filename.
 The default is not to present a  The default is not to present a
 hyperlink.  hyperlink.
 .It Cm man Ns = Ns Ar fmt  .It Cm man Ns = Ns Ar fmt Ns Op ; Ns Ar fmt
 The string  The string
 .Ar fmt ,  .Ar fmt ,
 for example,  for example,
 .Ar ../html%S/%N.%S.html ,  .Ar ../html%S/%N.%S.html ,
 is used as a template for linked manuals (usually via the  is used as a template for linked manuals (usually via the
 .Sq \&Xr  .Ic \&Xr
 macro).  macro).
 Instances of  Instances of
 .Sq \&%N  .Sq \&%N
Line 294  are replaced with the linked manual's name and section
Line 400  are replaced with the linked manual's name and section
 If no section is included, section 1 is assumed.  If no section is included, section 1 is assumed.
 The default is not to  The default is not to
 present a hyperlink.  present a hyperlink.
   If two formats are given and a file
   .Ar %N.%S
   exists in the current directory, the first format is used;
   otherwise, the second format is used.
 .It Cm style Ns = Ns Ar style.css  .It Cm style Ns = Ns Ar style.css
 The file  The file
 .Ar style.css  .Ar style.css
 is used for an external style-sheet.  is used for an external style-sheet.
 This must be a valid absolute or  This must be a valid absolute or
 relative URI.  relative URI.
   .It Cm tag Ns Op = Ns Ar term
   Same syntax and semantics as for
   .Sx ASCII Output .
   This is implemented by passing a
   .Ic file://
   URI ending in a fragment identifier to the pager
   rather than passing merely a file name.
   When using this argument, use a pager supporting such URIs, for example
   .Bd -literal -offset 3n
   MANPAGER='lynx -force_html' man -T html -O tag=MANPAGER man
   MANPAGER='w3m -T text/html' man -T html -O tag=toc mandoc
   .Ed
   .Pp
   Consequently, for HTML output, this argument does not work with
   .Xr more 1
   or
   .Xr less 1 .
   For example,
   .Ql MANPAGER=less man -T html -O tag=toc mandoc
   does not work because
   .Xr less 1
   does not support
   .Ic file://
   URIs.
   .It Cm toc
   If an input file contains at least two non-standard sections,
   print a table of contents near the beginning of the output.
 .El  .El
   .Ss Locale Output
   By default,
   .Nm
   automatically selects UTF-8 or ASCII output according to the current
   .Xr locale 1 .
   If any of the environment variables
   .Ev LC_ALL ,
   .Ev LC_CTYPE ,
   or
   .Ev LANG
   are set and the first one that is set
   selects the UTF-8 character encoding, it produces
   .Sx UTF-8 Output ;
   otherwise, it falls back to
   .Sx ASCII Output .
   This output mode can also be selected explicitly with
   .Fl T Cm locale .
   .Ss Man Output
   Use
   .Fl T Cm man
   to translate
   .Xr mdoc 7
   input into
   .Xr man 7
   output format.
   This is useful for distributing manual sources to legacy systems
   lacking
   .Xr mdoc 7
   formatters.
   Embedded
   .Xr eqn 7
   and
   .Xr tbl 7
   code is not supported.
   .Pp
   If the input format of a file is
   .Xr man 7 ,
   the input is copied to the output.
   The parser is also run, and as usual, the
   .Fl W
   level controls which
   .Sx DIAGNOSTICS
   are displayed before copying the input to the output.
   .Ss Markdown Output
   Use
   .Fl T Cm markdown
   to translate
   .Xr mdoc 7
   input to the markdown format conforming to
   .Lk https://daringfireball.net/projects/markdown/syntax.text\
    "John Gruber's 2004 specification" .
   The output also almost conforms to the
   .Lk https://commonmark.org/ CommonMark
   specification.
   .Pp
   The character set used for the markdown output is ASCII.
   Non-ASCII characters are encoded as HTML entities.
   Since that is not possible in literal font contexts, because these
   are rendered as code spans and code blocks in the markdown output,
   non-ASCII characters are transliterated to ASCII approximations in
   these contexts.
   .Pp
   Markdown is a very weak markup language, so all semantic markup is
   lost, and even part of the presentational markup may be lost.
   Do not use this as an intermediate step in converting to HTML;
   instead, use
   .Fl T Cm html
   directly.
   .Pp
   The
   .Xr man 7 ,
   .Xr tbl 7 ,
   and
   .Xr eqn 7
   input languages are not supported by
   .Fl T Cm markdown
   output mode.
   .Ss PDF Output
   PDF-1.1 output may be generated by
   .Fl T Cm pdf .
   See
   .Sx PostScript Output
   for
   .Fl O
   arguments and defaults.
 .Ss PostScript Output  .Ss PostScript Output
 PostScript  PostScript
 .Qq Adobe-3.0  .Qq Adobe-3.0
 Level-2 pages may be generated by  Level-2 pages may be generated by
 .Fl T Ns Cm ps .  .Fl T Cm ps .
 Output pages default to letter sized and are rendered in the Times font  Output pages default to letter sized and are rendered in the Times font
 family, 11-point.  family, 11-point.
 Margins are calculated as 1/9 the page length and width.  Margins are calculated as 1/9 the page length and width.
Line 335  If an unknown value is encountered,
Line 557  If an unknown value is encountered,
 .Ar letter  .Ar letter
 is used.  is used.
 .El  .El
 .Ss PDF Output  .Ss UTF-8 Output
 PDF-1.1 output may be generated by  Use
 .Fl T Ns Cm pdf .  .Fl T Cm utf8
   to force text output in UTF-8 multi-byte character encoding,
   ignoring the
   .Xr locale 1
   settings in the environment.
 See  See
 .Sx PostScript Output  .Sx ASCII Output
 for  regarding font styles and
 .Fl O  .Fl O
 arguments and defaults.  arguments.
 .Ss XHTML Output  
 Output produced by  
 .Fl T Ns Cm xhtml  
 conforms to XHTML-1.0 strict.  
 .Pp  .Pp
 See  On operating systems lacking locale or wide character support, and
 .Sx HTML Output  on those where the internal character representation is not UCS-4,
 for details; beyond generating XHTML tags instead of HTML tags, these  .Nm
 output modes are identical.  always falls back to
   .Sx ASCII Output .
   .Ss Syntax tree output
   Use
   .Fl T Cm tree
   to show a human readable representation of the syntax tree.
   It is useful for debugging the source code of manual pages.
   The exact format is subject to change, so don't write parsers for it.
   .Pp
   The first paragraph shows meta data found in the
   .Xr mdoc 7
   prologue, on the
   .Xr man 7
   .Ic \&TH
   line, or the fallbacks used.
   .Pp
   In the tree dump, each output line shows one syntax tree node.
   Child nodes are indented with respect to their parent node.
   The columns are:
   .Pp
   .Bl -enum -compact
   .It
   For macro nodes, the macro name; for text and
   .Xr tbl 7
   nodes, the content.
   There is a special format for
   .Xr eqn 7
   nodes.
   .It
   Node type (text, elem, block, head, body, body-end, tail, tbl, eqn).
   .It
   Flags:
   .Bl -dash -compact
   .It
   An opening parenthesis if the node is an opening delimiter.
   .It
   An asterisk if the node starts a new input line.
   .It
   The input line number (starting at one).
   .It
   A colon.
   .It
   The input column number (starting at one).
   .It
   A closing parenthesis if the node is a closing delimiter.
   .It
   A full stop if the node ends a sentence.
   .It
   BROKEN if the node is a block broken by another block.
   .It
   NOSRC if the node is not in the input file,
   but automatically generated from macros.
   .It
   NOPRT if the node is not supposed to generate output
   for any output format.
   .El
   .El
   .Pp
   The following
   .Fl O
   argument is accepted:
   .Bl -tag -width Ds
   .It Cm noval
   Skip validation and show the unvalidated syntax tree.
   This can help to find out whether a given behaviour is caused by
   the parser or by the validator.
   Meta data is not available in this case.
   .El
   .Sh ENVIRONMENT
   .Bl -tag -width MANPAGER
   .It Ev LC_CTYPE
   The character encoding
   .Xr locale 1 .
   When
   .Sx Locale Output
   is selected, it decides whether to use ASCII or UTF-8 output format.
   It never affects the interpretation of input files.
   .It Ev MANPAGER
   Any non-empty value of the environment variable
   .Ev MANPAGER
   is used instead of the standard pagination program,
   .Xr less 1 ;
   see
   .Xr man 1
   for details.
   Only used if
   .Fl a
   or
   .Fl l
   is specified.
   .It Ev PAGER
   Specifies the pagination program to use when
   .Ev MANPAGER
   is not defined.
   If neither PAGER nor MANPAGER is defined,
   .Xr less 1
   is used.
   Only used if
   .Fl a
   or
   .Fl l
   is specified.
   .El
   .Sh EXIT STATUS
   The
   .Nm
   utility exits with one of the following values, controlled by the message
   .Ar level
   associated with the
   .Fl W
   option:
   .Pp
   .Bl -tag -width Ds -compact
   .It 0
   No base system convention violations, style suggestions, warnings,
   or errors occurred, or those that did were ignored because they
   were lower than the requested
   .Ar level .
   .It 1
   At least one base system convention violation or style suggestion
   occurred, but no warning or error, and
   .Fl W Cm base
   or
   .Fl W Cm style
   was specified.
   .It 2
   At least one warning occurred, but no error, and
   .Fl W Cm warning
   or a lower
   .Ar level
   was requested.
   .It 3
   At least one parsing error occurred,
   but no unsupported feature was encountered, and
   .Fl W Cm error
   or a lower
   .Ar level
   was requested.
   .It 4
   At least one unsupported feature was encountered, and
   .Fl W Cm unsupp
   or a lower
   .Ar level
   was requested.
   .It 5
   Invalid command line arguments were specified.
   No input files have been read.
   .It 6
   An operating system error occurred, for example exhaustion
   of memory, file descriptors, or process table entries.
   Such errors may cause
   .Nm
   to exit at once, possibly in the middle of parsing or formatting a file.
   .El
   .Pp
   Note that selecting
   .Fl T Cm lint
   output mode implies
   .Fl W Cm all .
 .Sh EXAMPLES  .Sh EXAMPLES
 To page manuals to the terminal:  To page manuals to the terminal:
 .Pp  .Pp
 .D1 $ mandoc \-Wall,error \-fstrict mandoc.1 2\*(Gt&1 | less  .Dl $ mandoc -a mandoc.1 man.1 apropos.1 makewhatis.8
 .D1 $ mandoc mandoc.1 mdoc.3 mdoc.7 | less  
 .Pp  .Pp
 To produce HTML manuals with  To produce HTML manuals with
 .Ar style.css  .Pa /usr/share/misc/mandoc.css
 as the style-sheet:  as the style-sheet:
 .Pp  .Pp
 .D1 $ mandoc \-Thtml -Ostyle=style.css mdoc.7 \*(Gt mdoc.7.html  .Dl $ mandoc \-T html -O style=/usr/share/misc/mandoc.css mdoc.7 > mdoc.7.html
 .Pp  .Pp
 To check over a large set of manuals:  To check over a large set of manuals:
 .Pp  .Pp
 .Dl $ mandoc \-Tlint \-fign-errors `find /usr/src -name \e*\e.[1-9]`  .Dl $ mandoc \-T lint \(gafind /usr/src -name \e*\e.[1-9]\(ga
 .Pp  .Pp
 To produce a series of PostScript manuals for A4 paper:  To produce a series of PostScript manuals for A4 paper:
 .Pp  .Pp
 .D1 $ mandoc \-Tps \-Opaper=a4 mdoc.7 man.7 \*(Gt manuals.ps  .Dl $ mandoc \-T ps \-O paper=a4 mdoc.7 man.7 > manuals.ps
 .Sh COMPATIBILITY  .Pp
 This section summarises  Convert a modern
   .Xr mdoc 7
   manual to the older
   .Xr man 7
   format, for use on systems lacking an
   .Xr mdoc 7
   parser:
   .Pp
   .Dl $ mandoc \-T man foo.mdoc > foo.man
   .Sh DIAGNOSTICS
   Messages displayed by
 .Nm  .Nm
 compatibility with GNU troff.  follow this format:
 Each input and output format is separately noted.  .Bd -ragged -offset indent
 .Ss ASCII Compatibility  .Nm :
 .Bl -bullet -compact  .Ar file : Ns Ar line : Ns Ar column : level : message : macro arguments
 .It  .Pq Ar os
   .Ed
   .Pp
   The first three fields identify the
   .Ar file
   name,
   .Ar line
   number, and
   .Ar column
   number of the input file where the message was triggered.
   The line and column numbers start at 1.
   Both are omitted for messages referring to an input file as a whole.
   All
   .Ar level
   and
   .Ar message
   strings are explained below.
   The name of the
   .Ar macro
   triggering the message and its
   .Ar arguments
   are omitted where meaningless.
 The  The
 .Sq \&Bd \-literal  .Ar os
   operating system specifier is omitted for messages that are relevant
   for all operating systems.
   Fatal messages about invalid command line arguments
   or operating system errors, for example when memory is exhausted,
   may also omit the
   .Ar file
 and  and
 .Sq \&Bd \-unfilled  .Ar level
 macros of  fields.
   .Pp
   Message levels have the following meanings:
   .Bl -tag -width "warning"
   .It Cm syserr
   An operating system error occurred.
   There isn't necessarily anything wrong with the input files.
   Output may all the same be missing or incomplete.
   .It Cm badarg
   Invalid command line arguments were specified.
   No input files have been read and no output is produced.
   .It Cm unsupp
   An input file uses unsupported low-level
   .Xr roff 7
   features.
   The output may be incomplete and/or misformatted,
   so using GNU troff instead of
   .Nm
   to process the file may be preferable.
   .It Cm error
   Indicates a risk of information loss or severe misformatting,
   in most cases caused by serious syntax errors.
   .It Cm warning
   Indicates a risk that the information shown or its formatting
   may mismatch the author's intent in minor ways.
   Additionally, syntax errors are classified at least as warnings,
   even if they do not usually cause misformatting.
   .It Cm style
   An input file uses dubious or discouraged style.
   This is not a complaint about the syntax, and probably neither
   formatting nor portability are in danger.
   While great care is taken to avoid false positives on the higher
   message levels, the
   .Cm style
   level tries to reduce the probability that issues go unnoticed,
   so it may occasionally issue bogus suggestions.
   Use your judgement to decide whether any particular
   .Cm style
   suggestion really justifies a change to the input file.
   .It Cm base
   A convention used in the base system of a specific operating system
   is not adhered to.
   These are not markup mistakes, and neither the quality of formatting
   nor portability are in danger.
   Messages of the
   .Cm base
   level are printed with the more intuitive
   .Cm style
   .Ar level
   tag.
   .El
   .Pp
   Messages of the
   .Cm base ,
   .Cm style ,
   .Cm warning ,
   .Cm error ,
   and
   .Cm unsupp
   levels are hidden unless their level, or a lower level, is requested using a
   .Fl W
   option or
   .Fl T Cm lint
   output mode.
   .Pp
   As indicated below, all
   .Cm base
   and some
   .Cm style
   checks are only performed if a specific operating system name occurs
   in the arguments of the
   .Fl W
   command line option, of the
   .Ic \&Os
   macro, of the
   .Fl Ios
   command line option, or, if neither are present, in the return value
   of the
   .Xr uname 3
   function.
   .Ss Conventions for base system manuals
   .Bl -ohang
   .It Sy "Mdocdate found"
   .Pq mdoc , Nx
   The
   .Ic \&Dd
   macro uses CVS
   .Ic Mdocdate
   keyword substitution, which is not supported by the
   .Nx
   base system.
   Consider using the conventional
   .Dq "Month dd, yyyy"
   format instead.
   .It Sy "Mdocdate missing"
   .Pq mdoc , Ox
   The
   .Ic \&Dd
   macro does not use CVS
   .Ic Mdocdate
   keyword substitution, but using it is conventionally expected in the
   .Ox
   base system.
   .It Sy "unknown architecture"
   .Pq mdoc , Ox , Nx
   The third argument of the
   .Ic \&Dt
   macro does not match any of the architectures this operating system
   is running on.
   .It Sy "operating system explicitly specified"
   .Pq mdoc , Ox , Nx
   The
   .Ic \&Os
   macro has an argument.
   In the base system, it is conventionally left blank.
   .It Sy "RCS id missing"
   .Pq Ox , Nx
   The manual page lacks the comment line with the RCS identifier
   generated by CVS
   .Ic OpenBSD
   or
   .Ic NetBSD
   keyword substitution as conventionally used in these operating systems.
   .El
   .Ss Style suggestions
   .Bl -ohang
   .It Sy "legacy man(7) date format"
   .Pq mdoc
   The
   .Ic \&Dd
   macro uses the legacy
   .Xr man 7
   date format
   .Dq yyyy-dd-mm .
   Consider using the conventional
 .Xr mdoc 7  .Xr mdoc 7
 in  date format
 .Fl T Ns Cm ascii  .Dq "Month dd, yyyy"
 are synonyms, as are \-filled and \-ragged.  instead.
 .It  .It Sy "normalizing date format to" : No ...
 In GNU troff, the  .Pq mdoc , man
 .Sq \&Pa  The
   .Ic \&Dd
   or
   .Ic \&TH
   macro provides an abbreviated month name or a day number with a
   leading zero.
   In the formatted output, the month name is written out in full
   and the leading zero is omitted.
   .It Sy "lower case character in document title"
   .Pq mdoc , man
   The title is still used as given in the
   .Ic \&Dt
   or
   .Ic \&TH
   macro.
   .It Sy "duplicate RCS id"
   A single manual page contains two copies of the RCS identifier for
   the same operating system.
   Consider deleting the later instance and moving the first one up
   to the top of the page.
   .It Sy "possible typo in section name"
   .Pq mdoc
   Fuzzy string matching revealed that the argument of an
   .Ic \&Sh
   macro is similar, but not identical to a standard section name.
   .It Sy "unterminated quoted argument"
   .Pq roff
   Macro arguments can be enclosed in double quote characters
   such that space characters and macro names contained in the quoted
   argument need not be escaped.
   The closing quote of the last argument of a macro can be omitted.
   However, omitting it is not recommended because it makes the code
   harder to read.
   .It Sy "useless macro"
   .Pq mdoc
   A
   .Ic \&Bt ,
   .Ic \&Tn ,
   or
   .Ic \&Ud
   macro was found.
   Simply delete it: it serves no useful purpose.
   .It Sy "consider using OS macro"
   .Pq mdoc
   A string was found in plain text or in a
   .Ic \&Bx
   macro that could be represented using
   .Ic \&Ox ,
   .Ic \&Nx ,
   .Ic \&Fx ,
   or
   .Ic \&Dx .
   .It Sy "errnos out of order"
   .Pq mdoc, Nx
   The
   .Ic \&Er
   items in a
   .Ic \&Bl
   list are not in alphabetical order.
   .It Sy "duplicate errno"
   .Pq mdoc, Nx
   A
   .Ic \&Bl
   list contains two consecutive
   .Ic \&It
   entries describing the same
   .Ic \&Er
   number.
   .It Sy "referenced manual not found"
   .Pq mdoc
   An
   .Ic \&Xr
   macro references a manual page that was not found.
   When running with
   .Fl W Cm base ,
   the search is restricted to the base system, by default to
   .Pa /usr/share/man : Ns Pa /usr/X11R6/man .
   This path can be configured at compile time using the
   .Dv MANPATH_BASE
   preprocessor macro.
   When running with
   .Fl W Cm style ,
   the search is done along the full search path as described in the
   .Xr man 1
   manual page, respecting the
   .Fl m
   and
   .Fl M
   command line options, the
   .Ev MANPATH
   environment variable, the
   .Xr man.conf 5
   file and falling back to the default of
   .Pa /usr/share/man : Ns Pa /usr/X11R6/man : Ns Pa /usr/local/man ,
   also configurable at compile time using the
   .Dv MANPATH_DEFAULT
   preprocessor macro.
   .It Sy "trailing delimiter"
   .Pq mdoc
   The last argument of an
   .Ic \&Ex , \&Fo , \&Nd , \&Nm , \&Os , \&Sh , \&Ss , \&St ,
   or
   .Ic \&Sx
   macro ends with a trailing delimiter.
   This is usually bad style and often indicates typos.
   Most likely, the delimiter can be removed.
   .It Sy "no blank before trailing delimiter"
   .Pq mdoc
   The last argument of a macro that supports trailing delimiter
   arguments is longer than one byte and ends with a trailing delimiter.
   Consider inserting a blank such that the delimiter becomes a separate
   argument, thus moving it out of the scope of the macro.
   .It Sy "fill mode already enabled, skipping"
   .Pq man
   A
   .Ic \&fi
   request occurs even though the document is still in fill mode,
   or already switched back to fill mode.
   It has no effect.
   .It Sy "fill mode already disabled, skipping"
   .Pq man
   An
   .Ic \&nf
   request occurs even though the document already switched to no-fill mode
   and did not switch back to fill mode yet.
   It has no effect.
   .It Sy "input text line longer than 80 bytes"
   Consider breaking the input text line
   at one of the blank characters before column 80.
   .It Sy "verbatim \(dq--\(dq, maybe consider using \e(em"
   .Pq mdoc
   Even though the ASCII output device renders an em-dash as
   .Qq \-\- ,
   that is not a good way to write it in an input file
   because it renders poorly on all other output devices.
   .It Sy "function name without markup"
   .Pq mdoc
   A word followed by an empty pair of parentheses occurs on a text line.
   Consider using an
   .Ic \&Fn
   or
   .Ic \&Xr
   macro.
   .It Sy "whitespace at end of input line"
   .Pq mdoc , man , roff
   Whitespace at the end of input lines is almost never semantically
   significant \(em but in the odd case where it might be, it is
   extremely confusing when reviewing and maintaining documents.
   .It Sy "bad comment style"
   .Pq roff
   Comment lines start with a dot, a backslash, and a double-quote character.
   The
   .Nm
   utility treats the line as a comment line even without the backslash,
   but leaving out the backslash might not be portable.
   .El
   .Ss Warnings related to the document prologue
   .Bl -ohang
   .It Sy "missing manual title, using UNTITLED"
   .Pq mdoc
   A
   .Ic \&Dt
   macro has no arguments, or there is no
   .Ic \&Dt
   macro before the first non-prologue macro.
   .It Sy "missing manual title, using \(dq\(dq"
   .Pq man
   There is no
   .Ic \&TH
   macro, or it has no arguments.
   .It Sy "missing manual section, using \(dq\(dq"
   .Pq mdoc , man
   A
   .Ic \&Dt
   or
   .Ic \&TH
   macro lacks the mandatory section argument.
   .It Sy "unknown manual section"
   .Pq mdoc
   The section number in a
   .Ic \&Dt
   line is invalid, but still used.
   .It Sy "filename/section mismatch"
   .Pq mdoc , man
   The name of the input file being processed is known and its file
   name extension starts with a non-zero digit, but the
   .Ic \&Dt
   or
   .Ic \&TH
   macro contains a
   .Ar section
   argument that starts with a different non-zero digit.
   The
   .Ar section
   argument is used as provided anyway.
   Consider checking whether the file name or the argument need a correction.
   .It Sy "missing date, using \(dq\(dq"
   .Pq mdoc, man
   The document was parsed as
 .Xr mdoc 7  .Xr mdoc 7
 macro does not underline when scoped under an  and it has no
 .Sq \&It  .Ic \&Dd
 in the FILES section.  macro, or the
 This behaves correctly in  .Ic \&Dd
 .Nm .  macro has no arguments or only empty arguments;
 .It  or the document was parsed as
 A list or display following the  .Xr man 7
 .Sq \&Ss  and it has no
   .Ic \&TH
   macro, or the
   .Ic \&TH
   macro has less than three arguments or its third argument is empty.
   .It Sy "cannot parse date, using it verbatim"
   .Pq mdoc , man
   The date given in a
   .Ic \&Dd
   or
   .Ic \&TH
   macro does not follow the conventional format.
   .It Sy "date in the future, using it anyway"
   .Pq mdoc , man
   The date given in a
   .Ic \&Dd
   or
   .Ic \&TH
   macro is more than a day ahead of the current system
   .Xr time 3 .
   .It Sy "missing Os macro, using \(dq\(dq"
   .Pq mdoc
   The default or current system is not shown in this case.
   .It Sy "late prologue macro"
   .Pq mdoc
   A
   .Ic \&Dd
   or
   .Ic \&Os
   macro occurs after some non-prologue macro, but still takes effect.
   .It Sy "prologue macros out of order"
   .Pq mdoc
   The prologue macros are not given in the conventional order
   .Ic \&Dd ,
   .Ic \&Dt ,
   .Ic \&Os .
   All three macros are used even when given in another order.
   .El
   .Ss Warnings regarding document structure
   .Bl -ohang
   .It Sy ".so is fragile, better use ln(1)"
   .Pq roff
   Including files only works when the parser program runs with the correct
   current working directory.
   .It Sy "no document body"
   .Pq mdoc , man
   The document body contains neither text nor macros.
   An empty document is shown, consisting only of a header and a footer line.
   .It Sy "content before first section header"
   .Pq mdoc , man
   Some macros or text precede the first
   .Ic \&Sh
   or
   .Ic \&SH
   section header.
   The offending macros and text are parsed and added to the top level
   of the syntax tree, outside any section block.
   .It Sy "first section is not NAME"
   .Pq mdoc
   The argument of the first
   .Ic \&Sh
   macro is not
   .Sq NAME .
   This may confuse
   .Xr makewhatis 8
   and
   .Xr apropos 1 .
   .It Sy "NAME section without Nm before Nd"
   .Pq mdoc
   The NAME section does not contain any
   .Ic \&Nm
   child macro before the first
   .Ic \&Nd
   macro.
   .It Sy "NAME section without description"
   .Pq mdoc
   The NAME section lacks the mandatory
   .Ic \&Nd
   child macro.
   .It Sy "description not at the end of NAME"
   .Pq mdoc
   The NAME section does contain an
   .Ic \&Nd
   child macro, but other content follows it.
   .It Sy "bad NAME section content"
   .Pq mdoc
   The NAME section contains plain text or macros other than
   .Ic \&Nm
   and
   .Ic \&Nd .
   .It Sy "missing comma before name"
   .Pq mdoc
   The NAME section contains an
   .Ic \&Nm
   macro that is neither the first one nor preceded by a comma.
   .It Sy "missing description line, using \(dq\(dq"
   .Pq mdoc
   The
   .Ic \&Nd
   macro lacks the required argument.
   The title line of the manual will end after the dash.
   .It Sy "description line outside NAME section"
   .Pq mdoc
   An
   .Ic \&Nd
   macro appears outside the NAME section.
   The arguments are printed anyway and the following text is used for
   .Xr apropos 1 ,
   but none of that behaviour is portable.
   .It Sy "sections out of conventional order"
   .Pq mdoc
   A standard section occurs after another section it usually precedes.
   All section titles are used as given,
   and the order of sections is not changed.
   .It Sy "duplicate section title"
   .Pq mdoc
   The same standard section title occurs more than once.
   .It Sy "unexpected section"
   .Pq mdoc
   A standard section header occurs in a section of the manual
   where it normally isn't useful.
   .It Sy "cross reference to self"
   .Pq mdoc
   An
   .Ic \&Xr
   macro refers to a name and section matching the section of the present
   manual page and a name mentioned in an
   .Ic \&Nm
   macro in the NAME or SYNOPSIS section, or in an
   .Ic \&Fn
   or
   .Ic \&Fo
   macro in the SYNOPSIS.
   Consider using
   .Ic \&Nm
   or
   .Ic \&Fn
   instead of
   .Ic \&Xr .
   .It Sy "unusual Xr order"
   .Pq mdoc
   In the SEE ALSO section, an
   .Ic \&Xr
   macro with a lower section number follows one with a higher number,
   or two
   .Ic \&Xr
   macros referring to the same section are out of alphabetical order.
   .It Sy "unusual Xr punctuation"
   .Pq mdoc
   In the SEE ALSO section, punctuation between two
   .Ic \&Xr
   macros differs from a single comma, or there is trailing punctuation
   after the last
   .Ic \&Xr
   macro.
   .It Sy "AUTHORS section without An macro"
   .Pq mdoc
   An AUTHORS sections contains no
   .Ic \&An
   macros, or only empty ones.
   Probably, there are author names lacking markup.
   .El
   .Ss "Warnings related to macros and nesting"
   .Bl -ohang
   .It Sy "obsolete macro"
   .Pq mdoc
   See the
 .Xr mdoc 7  .Xr mdoc 7
 macro in  manual for replacements.
 .Fl T Ns Cm ascii  .It Sy "macro neither callable nor escaped"
 does not assert a prior vertical break, just as it doesn't with  .Pq mdoc
 .Sq \&Sh .  The name of a macro that is not callable appears on a macro line.
   It is printed verbatim.
   If the intention is to call it, move it to its own input line;
   otherwise, escape it by prepending
   .Sq \e& .
   .It Sy "skipping paragraph macro"
   In
   .Xr mdoc 7
   documents, this happens
   .Bl -dash -compact
 .It  .It
 The  at the beginning and end of sections and subsections
 .Sq \&na  .It
   right before non-compact lists and displays
   .It
   at the end of items in non-column, non-compact lists
   .It
   and for multiple consecutive paragraph macros.
   .El
   In
 .Xr man 7  .Xr man 7
 macro in  documents, it happens
 .Fl T Ns Cm ascii  .Bl -dash -compact
 has no effect.  
 .It  .It
 Words aren't hyphenated.  for empty
   .Ic \&P ,
   .Ic \&PP ,
   and
   .Ic \&LP
   macros
 .It  .It
 Sentences are unilaterally monospaced.  for
   .Ic \&IP
   macros having neither head nor body arguments
   .It
   for
   .Ic \&br
   or
   .Ic \&sp
   right after
   .Ic \&SH
   or
   .Ic \&SS
 .El  .El
 .Ss HTML/XHTML Compatibility  .It Sy "moving paragraph macro out of list"
 .Bl -bullet -compact  .Pq mdoc
   A list item in a
   .Ic \&Bl
   list contains a trailing paragraph macro.
   The paragraph macro is moved after the end of the list.
   .It Sy "skipping no-space macro"
   .Pq mdoc
   An input line begins with an
   .Ic \&Ns
   macro, or the next argument after an
   .Ic \&Ns
   macro is an isolated closing delimiter.
   The macro is ignored.
   .It Sy "blocks badly nested"
   .Pq mdoc
   If two blocks intersect, one should completely contain the other.
   Otherwise, rendered output is likely to look strange in any output
   format, and rendering in SGML-based output formats is likely to be
   outright wrong because such languages do not support badly nested
   blocks at all.
   Typical examples of badly nested blocks are
   .Qq Ic \&Ao \&Bo \&Ac \&Bc
   and
   .Qq Ic \&Ao \&Bq \&Ac .
   In these examples,
   .Ic \&Ac
   breaks
   .Ic \&Bo
   and
   .Ic \&Bq ,
   respectively.
   .It Sy "nested displays are not portable"
   .Pq mdoc
   A
   .Ic \&Bd ,
   .Ic \&D1 ,
   or
   .Ic \&Dl
   display occurs nested inside another
   .Ic \&Bd
   display.
   This works with
   .Nm ,
   but fails with most other implementations.
   .It Sy "moving content out of list"
   .Pq mdoc
   A
   .Ic \&Bl
   list block contains text or macros before the first
   .Ic \&It
   macro.
   The offending children are moved before the beginning of the list.
   .It Sy "first macro on line"
   Inside a
   .Ic \&Bl Fl column
   list, a
   .Ic \&Ta
   macro occurs as the first macro on a line, which is not portable.
   .It Sy "line scope broken"
   .Pq man
   While parsing the next-line scope of the previous macro,
   another macro is found that prematurely terminates the previous one.
   The previous, interrupted macro is deleted from the parse tree.
   .El
   .Ss "Warnings related to missing arguments"
   .Bl -ohang
   .It Sy "skipping empty request"
   .Pq roff , eqn
   The macro name is missing from a macro definition request,
   or an
   .Xr eqn 7
   control statement or operation keyword lacks its required argument.
   .It Sy "conditional request controls empty scope"
   .Pq roff
   A conditional request is only useful if any of the following
   follows it on the same logical input line:
   .Bl -dash -compact
 .It  .It
 The  The
 .Sq \efP  .Sq \e{
 escape will revert the font to the previous  keyword to open a multi-line scope.
 .Sq \ef  
 escape, not to the last rendered decoration, which is now dictated by  
 CSS instead of hard-coded.  
 It also will not span past the current scope,  
 for the same reason.  
 Note that in  
 .Sx ASCII Output  
 mode, this will work fine.  
 .It  .It
   A request or macro or some text, resulting in a single-line scope.
   .It
   The immediate end of the logical line without any intervening whitespace,
   resulting in next-line scope.
   .El
   Here, a conditional request is followed by trailing whitespace only,
   and there is no other content on its logical input line.
   Note that it doesn't matter whether the logical input line is split
   across multiple physical input lines using
   .Sq \e
   line continuation characters.
   This is one of the rare cases
   where trailing whitespace is syntactically significant.
   The conditional request controls a scope containing whitespace only,
   so it is unlikely to have a significant effect,
   except that it may control a following
   .Ic \&el
   clause.
   .It Sy "skipping empty macro"
   .Pq mdoc
   The indicated macro has no arguments and hence no effect.
   .It Sy "empty block"
   .Pq mdoc , man
   A
   .Ic \&Bd ,
   .Ic \&Bk ,
   .Ic \&Bl ,
   .Ic \&D1 ,
   .Ic \&Dl ,
   .Ic \&MT ,
   .Ic \&RS ,
   or
   .Ic \&UR
   block contains nothing in its body and will produce no output.
   .It Sy "empty argument, using 0n"
   .Pq mdoc
   The required width is missing after
   .Ic \&Bd
   or
   .Ic \&Bl
   .Fl offset
   or
   .Fl width .
   .It Sy "missing display type, using -ragged"
   .Pq mdoc
 The  The
   .Ic \&Bd
   macro is invoked without the required display type.
   .It Sy "list type is not the first argument"
   .Pq mdoc
   In a
   .Ic \&Bl
   macro, at least one other argument precedes the type argument.
   The
   .Nm
   utility copes with any argument order, but some other
 .Xr mdoc 7  .Xr mdoc 7
 .Sq \&Bl \-hang  implementations do not.
   .It Sy "missing -width in -tag list, using 8n"
   .Pq mdoc
   Every
   .Ic \&Bl
   macro having the
   .Fl tag
   argument requires
   .Fl width ,
   too.
   .It Sy "missing utility name, using \(dq\(dq"
   .Pq mdoc
   The
   .Ic \&Ex Fl std
   macro is called without an argument before
   .Ic \&Nm
   has first been called with an argument.
   .It Sy "missing function name, using \(dq\(dq"
   .Pq mdoc
   The
   .Ic \&Fo
   macro is called without an argument.
   No function name is printed.
   .It Sy "empty head in list item"
   .Pq mdoc
   In a
   .Ic \&Bl
   .Fl diag ,
   .Fl hang ,
   .Fl inset ,
   .Fl ohang ,
   or
   .Fl tag
   list, an
   .Ic \&It
   macro lacks the required argument.
   The item head is left empty.
   .It Sy "empty list item"
   .Pq mdoc
   In a
   .Ic \&Bl
   .Fl bullet ,
   .Fl dash ,
   .Fl enum ,
   or
   .Fl hyphen
   list, an
   .Ic \&It
   block is empty.
   An empty list item is shown.
   .It Sy "missing argument, using next line"
   .Pq mdoc
   An
   .Ic \&It
   macro in a
   .Ic \&Bd Fl column
   list has no arguments.
   While
   .Nm
   uses the text or macros of the following line, if any, for the cell,
   other formatters may misformat the list.
   .It Sy "missing font type, using \efR"
   .Pq mdoc
   A
   .Ic \&Bf
   macro has no argument.
   It switches to the default font.
   .It Sy "unknown font type, using \efR"
   .Pq mdoc
   The
   .Ic \&Bf
   argument is invalid.
   The default font is used instead.
   .It Sy "nothing follows prefix"
   .Pq mdoc
   A
   .Ic \&Pf
   macro has no argument, or only one argument and no macro follows
   on the same input line.
   This defeats its purpose; in particular, spacing is not suppressed
   before the text or macros following on the next input line.
   .It Sy "empty reference block"
   .Pq mdoc
   An
   .Ic \&Rs
   macro is immediately followed by an
   .Ic \&Re
   macro on the next input line.
   Such an empty block does not produce any output.
   .It Sy "missing section argument"
   .Pq mdoc
   An
   .Ic \&Xr
   macro lacks its second, section number argument.
   The first argument, i.e. the name, is printed, but without subsequent
   parentheses.
   .It Sy "missing -std argument, adding it"
   .Pq mdoc
   An
   .Ic \&Ex
   or
   .Ic \&Rv
   macro lacks the required
   .Fl std
   argument.
   The
   .Nm
   utility assumes
   .Fl std
   even when it is not specified, but other implementations may not.
   .It Sy "missing option string, using \(dq\(dq"
   .Pq man
   The
   .Ic \&OP
   macro is invoked without any argument.
   An empty pair of square brackets is shown.
   .It Sy "missing resource identifier, using \(dq\(dq"
   .Pq man
   The
   .Ic \&MT
   or
   .Ic \&UR
   macro is invoked without any argument.
   An empty pair of angle brackets is shown.
   .It Sy "missing eqn box, using \(dq\(dq"
   .Pq eqn
   A diacritic mark or a binary operator is found,
   but there is nothing to the left of it.
   An empty box is inserted.
   .El
   .Ss "Warnings related to bad macro arguments"
   .Bl -ohang
   .It Sy "duplicate argument"
   .Pq mdoc
   A
   .Ic \&Bd
   or
   .Ic \&Bl
   macro has more than one
   .Fl compact ,
   more than one
   .Fl offset ,
   or more than one
   .Fl width
   argument.
   All but the last instances of these arguments are ignored.
   .It Sy "skipping duplicate argument"
   .Pq mdoc
   An
   .Ic \&An
   macro has more than one
   .Fl split
   or
   .Fl nosplit
   argument.
   All but the first of these arguments are ignored.
   .It Sy "skipping duplicate display type"
   .Pq mdoc
   A
   .Ic \&Bd
   macro has more than one type argument; the first one is used.
   .It Sy "skipping duplicate list type"
   .Pq mdoc
   A
   .Ic \&Bl
   macro has more than one type argument; the first one is used.
   .It Sy "skipping -width argument"
   .Pq mdoc
   A
   .Ic \&Bl
   .Fl column ,
   .Fl diag ,
   .Fl ohang ,
   .Fl inset ,
   or
   .Fl item
   list has a
   .Fl width
   argument.
   That has no effect.
   .It Sy "wrong number of cells"
   In a line of a
   .Ic \&Bl Fl column
   list, the number of tabs or
   .Ic \&Ta
   macros is less than the number expected from the list header line
   or exceeds the expected number by more than one.
   Missing cells remain empty, and all cells exceeding the number of
   columns are joined into one single cell.
   .It Sy "unknown AT&T UNIX version"
   .Pq mdoc
   An
   .Ic \&At
   macro has an invalid argument.
   It is used verbatim, with
   .Qq "AT&T UNIX "
   prefixed to it.
   .It Sy "comma in function argument"
   .Pq mdoc
   An argument of an
   .Ic \&Fa
   or
   .Ic \&Fn
   macro contains a comma; it should probably be split into two arguments.
   .It Sy "parenthesis in function name"
   .Pq mdoc
   The first argument of an
   .Ic \&Fc
   or
   .Ic \&Fn
   macro contains an opening or closing parenthesis; that's probably wrong,
   parentheses are added automatically.
   .It Sy "unknown library name"
   .Pq mdoc, not on Ox
   An
   .Ic \&Lb
   macro has an unknown name argument and will be rendered as
   .Qq library Dq Ar name .
   .It Sy "invalid content in Rs block"
   .Pq mdoc
   An
   .Ic \&Rs
   block contains plain text or non-% macros.
   The bogus content is left in the syntax tree.
   Formatting may be poor.
   .It Sy "invalid Boolean argument"
   .Pq mdoc
   An
   .Ic \&Sm
   macro has an argument other than
   .Cm on
   or
   .Cm off .
   The invalid argument is moved out of the macro, which leaves the macro
   empty, causing it to toggle the spacing mode.
   .It Sy "argument contains two font escapes"
   .Pq roff
   The second argument of a
   .Ic char
   request contains more than one font escape sequence.
   A wrong font may remain active after using the character.
   .It Sy "unknown font, skipping request"
   .Pq man , tbl
   A
   .Xr roff 7
   .Ic \&ft
   request or a
   .Xr tbl 7
   .Ic \&f
   layout modifier has an unknown
   .Ar font
   argument.
   .It Sy "ignoring distance argument"
   .Pq roff
   In addition to the margin character, an
   .Ic \&mc
   request has a second argument supposed to represent a distance, but the
   .Nm
   implementation of
   .Ic \&mc
   always ignores the second argument.
   .It Sy "odd number of characters in request"
   .Pq roff
   A
   .Ic \&tr
   request contains an odd number of characters.
   The last character is mapped to the blank character.
   .El
   .Ss "Warnings related to plain text"
   .Bl -ohang
   .It Sy "blank line in fill mode, using .sp"
   .Pq mdoc
   The meaning of blank input lines is only well-defined in non-fill mode:
   In fill mode, line breaks of text input lines are not supposed to be
   significant.
   However, for compatibility with groff, blank lines in fill mode
   are formatted like
   .Ic \&sp
   requests.
   To request a paragraph break, use
   .Ic \&Pp
   instead of a blank line.
   .It Sy "tab in filled text"
   .Pq mdoc , man
   The meaning of tab characters is only well-defined in non-fill mode:
   In fill mode, whitespace is not supposed to be significant
   on text input lines.
   As an implementation dependent choice, tab characters on text lines
   are passed through to the formatters in any case.
   Given that the text before the tab character will be filled,
   it is hard to predict which tab stop position the tab will advance to.
   .It Sy "new sentence, new line"
   .Pq mdoc
   A new sentence starts in the middle of a text line.
   Start it on a new input line to help formatters produce correct spacing.
   .It Sy "invalid escape sequence"
   .Pq roff
   An escape sequence has an invalid opening argument delimiter, lacks the
   closing argument delimiter, the argument is of an invalid form, or it is
   a character escape sequence with an invalid name.
   If the argument is incomplete,
   .Ic \e*
 and  and
 .Sq \&Bl \-tag  .Ic \en
 list types render similarly (no break following overreached left-hand  expand to an empty string,
 side) due to the expressive constraints of HTML.  .Ic \eB
   to the digit
   .Sq 0 ,
   and
   .Ic \ew
   to the length of the incomplete argument.
   All other invalid escape sequences are ignored.
   .It Sy "undefined escape, printing literally"
   .Pq roff
   In an escape sequence, the first character
   right after the leading backslash is invalid.
   That character is printed literally,
   which is equivalent to ignoring the backslash.
   .It Sy "undefined string, using \(dq\(dq"
   .Pq roff
   If a string is used without being defined before,
   its value is implicitly set to the empty string.
   However, defining strings explicitly before use
   keeps the code more readable.
   .El
   .Ss "Warnings related to tables"
   .Bl -ohang
   .It Sy "tbl line starts with span"
   .Pq tbl
   The first cell in a table layout line is a horizontal span
   .Pq Sq Cm s .
   Data provided for this cell is ignored, and nothing is printed in the cell.
   .It Sy "tbl column starts with span"
   .Pq tbl
   The first line of a table layout specification
   requests a vertical span
   .Pq Sq Cm ^ .
   Data provided for this cell is ignored, and nothing is printed in the cell.
   .It Sy "skipping vertical bar in tbl layout"
   .Pq tbl
   A table layout specification contains more than two consecutive vertical bars.
   A double bar is printed, all additional bars are discarded.
   .El
   .Ss "Errors related to tables"
   .Bl -ohang
   .It Sy "non-alphabetic character in tbl options"
   .Pq tbl
   The table options line contains a character other than a letter,
   blank, or comma where the beginning of an option name is expected.
   The character is ignored.
   .It Sy "skipping unknown tbl option"
   .Pq tbl
   The table options line contains a string of letters that does not
   match any known option name.
   The word is ignored.
   .It Sy "missing tbl option argument"
   .Pq tbl
   A table option that requires an argument is not followed by an
   opening parenthesis, or the opening parenthesis is immediately
   followed by a closing parenthesis.
   The option is ignored.
   .It Sy "wrong tbl option argument size"
   .Pq tbl
   A table option argument contains an invalid number of characters.
   Both the option and the argument are ignored.
   .It Sy "empty tbl layout"
   .Pq tbl
   A table layout specification is completely empty,
   specifying zero lines and zero columns.
   As a fallback, a single left-justified column is used.
   .It Sy "invalid character in tbl layout"
   .Pq tbl
   A table layout specification contains a character that can neither
   be interpreted as a layout key character nor as a layout modifier,
   or a modifier precedes the first key.
   The invalid character is discarded.
   .It Sy "unmatched parenthesis in tbl layout"
   .Pq tbl
   A table layout specification contains an opening parenthesis,
   but no matching closing parenthesis.
   The rest of the input line, starting from the parenthesis, has no effect.
   .It Sy "ignoring excessive spacing in tbl layout"
   .Pq tbl
   A spacing modifier in a table layout is unreasonably large.
   The default spacing of 3n is used instead.
   .It Sy "tbl without any data cells"
   .Pq tbl
   A table does not contain any data cells.
   It will probably produce no output.
   .It Sy "ignoring data in spanned tbl cell"
   .Pq tbl
   A table cell is marked as a horizontal span
   .Pq Sq Cm s
   or vertical span
   .Pq Sq Cm ^
   in the table layout, but it contains data.
   The data is ignored.
   .It Sy "ignoring extra tbl data cells"
   .Pq tbl
   A data line contains more cells than the corresponding layout line.
   The data in the extra cells is ignored.
   .It Sy "data block open at end of tbl"
   .Pq tbl
   A data block is opened with
   .Cm T{ ,
   but never closed with a matching
   .Cm T} .
   The remaining data lines of the table are all put into one cell,
   and any remaining cells stay empty.
   .El
   .Ss "Errors related to roff, mdoc, and man code"
   .Bl -ohang
   .It Sy "duplicate prologue macro"
   .Pq mdoc
   One of the prologue macros occurs more than once.
   The last instance overrides all previous ones.
   .It Sy "skipping late title macro"
   .Pq mdoc
   The
   .Ic \&Dt
   macro appears after the first non-prologue macro.
   Traditional formatters cannot handle this because
   they write the page header before parsing the document body.
   Even though this technical restriction does not apply to
   .Nm ,
   traditional semantics is preserved.
   The late macro is discarded including its arguments.
   .It Sy "input stack limit exceeded, infinite loop?"
   .Pq roff
   Explicit recursion limits are implemented for the following features,
   in order to prevent infinite loops:
   .Bl -dash -compact
 .It  .It
   expansion of nested escape sequences
   including expansion of strings and number registers,
   .It
   expansion of nested user-defined macros,
   .It
   and
   .Ic \&so
   file inclusion.
   .El
   When a limit is hit, the output is incorrect, typically losing
   some content, but the parser can continue.
   .It Sy "skipping bad character"
   .Pq mdoc , man , roff
   The input file contains a byte that is not a printable
   .Xr ascii 7
   character.
   The message mentions the character number.
   The offending byte is replaced with a question mark
   .Pq Sq \&? .
   Consider editing the input file to replace the byte with an ASCII
   transliteration of the intended character.
   .It Sy "skipping unknown macro"
   .Pq mdoc , man , roff
   The first identifier on a request or macro line is neither recognized as a
   .Xr roff 7
   request, nor as a user-defined macro, nor, respectively, as an
   .Xr mdoc 7
   or
   .Xr man 7
   macro.
   It may be mistyped or unsupported.
   The request or macro is discarded including its arguments.
   .It Sy "skipping request outside macro"
   .Pq roff
   A
   .Ic shift
   or
   .Ic return
   request occurs outside any macro definition and has no effect.
   .It Sy "skipping insecure request"
   .Pq roff
   An input file attempted to run a shell command
   or to read or write an external file.
   Such attempts are denied for security reasons.
   .It Sy "skipping item outside list"
   .Pq mdoc , eqn
   An
   .Ic \&It
   macro occurs outside any
   .Ic \&Bl
   list, or an
   .Xr eqn 7
   .Ic above
   delimiter occurs outside any pile.
   It is discarded including its arguments.
   .It Sy "skipping column outside column list"
   .Pq mdoc
   A
   .Ic \&Ta
   macro occurs outside any
   .Ic \&Bl Fl column
   block.
   It is discarded including its arguments.
   .It Sy "skipping end of block that is not open"
   .Pq mdoc , man , eqn , tbl , roff
   Various syntax elements can only be used to explicitly close blocks
   that have previously been opened.
   An
   .Xr mdoc 7
   block closing macro, a
   .Xr man 7
   .Ic \&ME , \&RE
   or
   .Ic \&UE
   macro, an
   .Xr eqn 7
   right delimiter or closing brace, or the end of an equation, table, or
   .Xr roff 7
   conditional request is encountered but no matching block is open.
   The offending request or macro is discarded.
   .It Sy "fewer RS blocks open, skipping"
   .Pq man
 The  The
   .Ic \&RE
   macro is invoked with an argument, but less than the specified number of
   .Ic \&RS
   blocks is open.
   The
   .Ic \&RE
   macro is discarded.
   .It Sy "inserting missing end of block"
   .Pq mdoc , tbl
   Various
   .Xr mdoc 7
   macros as well as tables require explicit closing by dedicated macros.
   A block that doesn't support bad nesting
   ends before all of its children are properly closed.
   The open child nodes are closed implicitly.
   .It Sy "appending missing end of block"
   .Pq mdoc , man , eqn , tbl , roff
   At the end of the document, an explicit
   .Xr mdoc 7
   block, a
 .Xr man 7  .Xr man 7
 .Sq IP  next-line scope or
   .Ic \&MT , \&RS
   or
   .Ic \&UR
   block, an equation, table, or
   .Xr roff 7
   conditional or ignore block is still open.
   The open block is closed implicitly.
   .It Sy "escaped character not allowed in a name"
   .Pq roff
   Macro, string and register identifiers consist of printable,
   non-whitespace ASCII characters.
   Escape sequences and characters and strings expressed in terms of them
   cannot form part of a name.
   The first argument of an
   .Ic \&am ,
   .Ic \&as ,
   .Ic \&de ,
   .Ic \&ds ,
   .Ic \&nr ,
   or
   .Ic \&rr
   request, or any argument of an
   .Ic \&rm
   request, or the name of a request or user defined macro being called,
   is terminated by an escape sequence.
   In the cases of
   .Ic \&as ,
   .Ic \&ds ,
 and  and
 .Sq TP  .Ic \&nr ,
 lists render similarly.  the request has no effect at all.
   In the cases of
   .Ic \&am ,
   .Ic \&de ,
   .Ic \&rr ,
   and
   .Ic \&rm ,
   what was parsed up to this point is used as the arguments to the request,
   and the rest of the input line is discarded including the escape sequence.
   When parsing for a request or a user-defined macro name to be called,
   only the escape sequence is discarded.
   The characters preceding it are used as the request or macro name,
   the characters following it are used as the arguments to the request or macro.
   .It Sy "using macro argument outside macro"
   .Pq roff
   The escape sequence \e$ occurs outside any macro definition
   and expands to the empty string.
   .It Sy "argument number is not numeric"
   .Pq roff
   The argument of the escape sequence \e$ is not a digit;
   the escape sequence expands to the empty string.
   .It Sy "negative argument, using 0"
   .Pq roff
   A
   .Ic \&shift
   request has a negative argument
   or an argument that is negative due to integer overflow.
   Macro argument numbering remains unchanged.
   .It Sy "NOT IMPLEMENTED: Bd -file"
   .Pq mdoc
   For security reasons, the
   .Ic \&Bd
   macro does not support the
   .Fl file
   argument.
   By requesting the inclusion of a sensitive file, a malicious document
   might otherwise trick a privileged user into inadvertently displaying
   the file on the screen, revealing the file content to bystanders.
   The argument is ignored including the file name following it.
   .It Sy "skipping display without arguments"
   .Pq mdoc
   A
   .Ic \&Bd
   block macro does not have any arguments.
   The block is discarded, and the block content is displayed in
   whatever mode was active before the block.
   .It Sy "missing list type, using -item"
   .Pq mdoc
   A
   .Ic \&Bl
   macro fails to specify the list type.
   .It Sy "argument is not numeric, using 1"
   .Pq roff
   The argument of a
   .Ic \&ce
   request is not a number.
   .It Sy "argument is not a character"
   .Pq roff
   The first argument of a
   .Ic char
   request is neither a single ASCII character
   nor a single character escape sequence.
   The request is ignored including all its arguments.
   .It Sy "skipping unusable escape sequence"
   .Pq roff
   The first argument of an
   .Ic mc
   request is neither a single ASCII character
   nor a single character escape sequence.
   All arguments are ignored and printing of a margin character is disabled.
   .It Sy "missing manual name, using \(dq\(dq"
   .Pq mdoc
   The first call to
   .Ic \&Nm ,
   or any call in the NAME section, lacks the required argument.
   .It Sy "uname(3) system call failed, using UNKNOWN"
   .Pq mdoc
   The
   .Ic \&Os
   macro is called without arguments, and the
   .Xr uname 3
   system call failed.
   As a workaround,
   .Nm
   can be compiled with
   .Sm off
   .Fl D Cm OSNAME=\(dq\e\(dq Ar string Cm \e\(dq\(dq .
   .Sm on
   .It Sy "unknown standard specifier"
   .Pq mdoc
   An
   .Ic \&St
   macro has an unknown argument and is discarded.
   .It Sy "skipping request without numeric argument"
   .Pq roff , eqn
   An
   .Ic \&it
   request or an
   .Xr eqn 7
   .Ic \&size
   or
   .Ic \&gsize
   statement has a non-numeric or negative argument or no argument at all.
   The invalid request or statement is ignored.
   .It Sy "excessive shift"
   .Pq roff
   The argument of a
   .Ic shift
   request is larger than the number of arguments of the macro that is
   currently being executed.
   All macro arguments are deleted and \en(.$ is set to zero.
   .It Sy "NOT IMPLEMENTED: .so with absolute path or \(dq..\(dq"
   .Pq roff
   For security reasons,
   .Nm
   allows
   .Ic \&so
   file inclusion requests only with relative paths
   and only without ascending to any parent directory.
   By requesting the inclusion of a sensitive file, a malicious document
   might otherwise trick a privileged user into inadvertently displaying
   the file on the screen, revealing the file content to bystanders.
   .Nm
   only shows the path as it appears behind
   .Ic \&so .
   .It Sy ".so request failed"
   .Pq roff
   Servicing a
   .Ic \&so
   request requires reading an external file, but the file could not be
   opened.
   .Nm
   only shows the path as it appears behind
   .Ic \&so .
   .It Sy "skipping all arguments"
   .Pq mdoc , man , eqn , roff
   An
   .Xr mdoc 7
   .Ic \&Bt ,
   .Ic \&Ed ,
   .Ic \&Ef ,
   .Ic \&Ek ,
   .Ic \&El ,
   .Ic \&Lp ,
   .Ic \&Pp ,
   .Ic \&Re ,
   .Ic \&Rs ,
   or
   .Ic \&Ud
   macro, an
   .Ic \&It
   macro in a list that don't support item heads, a
   .Xr man 7
   .Ic \&LP ,
   .Ic \&P ,
   or
   .Ic \&PP
   macro, an
   .Xr eqn 7
   .Ic \&EQ
   or
   .Ic \&EN
   macro, or a
   .Xr roff 7
   .Ic \&br ,
   .Ic \&fi ,
   or
   .Ic \&nf
   request or
   .Sq \&..
   block closing request is invoked with at least one argument.
   All arguments are ignored.
   .It Sy "skipping excess arguments"
   .Pq mdoc , man , roff
   A macro or request is invoked with too many arguments:
   .Bl -dash -offset 2n -width 2n -compact
   .It
   .Ic \&Fo ,
   .Ic \&MT ,
   .Ic \&PD ,
   .Ic \&RS ,
   .Ic \&UR ,
   .Ic \&ft ,
   or
   .Ic \&sp
   with more than one argument
   .It
   .Ic \&An
   with another argument after
   .Fl split
   or
   .Fl nosplit
   .It
   .Ic \&RE
   with more than one argument or with a non-integer argument
   .It
   .Ic \&OP
   or a request of the
   .Ic \&de
   family with more than two arguments
   .It
   .Ic \&Dt
   with more than three arguments
   .It
   .Ic \&TH
   with more than five arguments
   .It
   .Ic \&Bd ,
   .Ic \&Bk ,
   or
   .Ic \&Bl
   with invalid arguments
 .El  .El
   The excess arguments are ignored.
   .El
   .Ss Unsupported features
   .Bl -ohang
   .It Sy "input too large"
   .Pq mdoc , man
   Currently,
   .Nm
   cannot handle input files larger than its arbitrary size limit
   of 2^31 bytes (2 Gigabytes).
   Since useful manuals are always small, this is not a problem in practice.
   Parsing is aborted as soon as the condition is detected.
   .It Sy "unsupported control character"
   .Pq roff
   An ASCII control character supported by other
   .Xr roff 7
   implementations but not by
   .Nm
   was found in an input file.
   It is replaced by a question mark.
   .It Sy "unsupported escape sequence"
   .Pq roff
   An input file contains an escape sequence supported by GNU troff
   or Heirloom troff but not by
   .Nm ,
   and it is likely that this will cause information loss
   or considerable misformatting.
   .It Sy "unsupported roff request"
   .Pq roff
   An input file contains a
   .Xr roff 7
   request supported by GNU troff or Heirloom troff but not by
   .Nm ,
   and it is likely that this will cause information loss
   or considerable misformatting.
   .It Sy "eqn delim option in tbl"
   .Pq eqn , tbl
   The options line of a table defines equation delimiters.
   Any equation source code contained in the table will be printed unformatted.
   .It Sy "unsupported table layout modifier"
   .Pq tbl
   A table layout specification contains an
   .Sq Cm m
   modifier.
   The modifier is discarded.
   .It Sy "ignoring macro in table"
   .Pq tbl , mdoc , man
   A table contains an invocation of an
   .Xr mdoc 7
   or
   .Xr man 7
   macro or of an undefined macro.
   The macro is ignored, and its arguments are handled
   as if they were a text line.
   .It Sy "skipping tbl in -Tman mode"
   .Pq mdoc , tbl
   An input file contains the
   .Ic \&TS
   macro.
   This message is only generated in
   .Fl T Cm man
   output mode, where
   .Xr tbl 7
   input is not supported.
   .It Sy "skipping eqn in -Tman mode"
   .Pq mdoc , eqn
   An input file contains the
   .Ic \&EQ
   macro.
   This message is only generated in
   .Fl T Cm man
   output mode, where
   .Xr eqn 7
   input is not supported.
   .El
   .Ss Bad command line arguments
   .Bl -ohang
   .It Sy "bad command line argument"
   The argument following one of the
   .Fl IKMmOTW
   command line options is invalid, or a
   .Ar file
   given as a command line argument cannot be opened.
   .It Sy "duplicate command line argument"
   The
   .Fl I
   command line option was specified twice.
   .It Sy "option has a superfluous value"
   An argument to the
   .Fl O
   option has a value but does not accept one.
   .It Sy "missing option value"
   An argument to the
   .Fl O
   option has no argument but requires one.
   .It Sy "bad option value"
   An argument to the
   .Fl O
   .Cm indent
   or
   .Cm width
   option has an invalid value.
   .It Sy "duplicate option value"
   The same
   .Fl O
   option is specified more than once.
   .It Sy "no such tag"
   The
   .Fl O Cm tag
   option was specified but the tag was not found in any of the displayed
   manual pages.
   .It Sy "\-Tmarkdown unsupported for man(7) input"
   .Pq man
   The
   .Fl T Cm markdown
   option was specified but an input file uses the
   .Xr man 7
   language.
   No output is produced for that input file.
   .El
 .Sh SEE ALSO  .Sh SEE ALSO
   .Xr apropos 1 ,
   .Xr man 1 ,
   .Xr eqn 7 ,
 .Xr man 7 ,  .Xr man 7 ,
 .Xr mandoc_char 7 ,  .Xr mandoc_char 7 ,
 .Xr mdoc 7  .Xr mdoc 7 ,
 .Sh AUTHORS  .Xr roff 7 ,
   .Xr tbl 7
   .Sh HISTORY
 The  The
 .Nm  .Nm
 utility was written by  utility first appeared in
 .An Kristaps Dzonsons Aq kristaps@bsd.lv .  .Ox 4.8 .
 .Sh CAVEATS  The option
 The  .Fl I
 .Fl T Ns Cm html  appeared in
   .Ox 5.2 ,
 and  and
 .Fl T Ns Cm xhtml  .Fl aCcfhKklMSsw
 CSS2 styling used for  in
 .Fl m Ns Cm doc  .Ox 5.7 .
 input lists does not render properly in older browsers, such as Internet  .Sh AUTHORS
 Explorer 6 and earlier.  .An -nosplit
 .Pp  
 In  
 .Fl T Ns Cm html  
 and  
 .Fl T Ns Cm xhtml ,  
 the maximum size of an element attribute is determined by  
 .Dv BUFSIZ ,  
 which is usually 1024 bytes.  
 Be aware of this when setting long link  
 formats such as  
 .Fl O Ns Cm style Ns = Ns Ar really/long/link .  
 .Pp  
 Nesting elements within next-line element scopes of  
 .Fl m Ns Cm an ,  
 such as  
 .Sq br  
 within an empty  
 .Sq B ,  
 will confuse  
 .Fl T Ns Cm html  
 and  
 .Fl T Ns Cm xhtml  
 and cause them to forget the formatting of the prior next-line scope.  
 .Pp  
 The  The
 .Sq i  .Nm
 macro in  utility was written by
 .Fl m Ns Cm an  .An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
 should italicise all subsequent text if a line argument is not provided.  and is maintained by
 This behaviour is not implemented.  .An Ingo Schwarze Aq Mt schwarze@openbsd.org .
 The  
 .Sq \(aq  
 control character is an alias for the standard macro control character  
 and does not emit a line-break as stipulated in GNU troff.  
Legend:
Removed from v.1.76  
changed lines
  Added in v.1.258
CVSweb