Provided by: mandoc_1.14.3-3_amd64 bug

NAME

       mandoc - format manual pages

SYNOPSIS

       mandoc [-ac] [-I os=name] [-K encoding] [-mdoc | -man] [-O options] [-T output] [-W level] [file ...]

DESCRIPTION

       The mandoc utility formats UNIX manual pages for display.

       By default, mandoc reads mdoc(7) or man(7) text from stdin and produces -T locale output.

       The options are as follows:

       -a      If the standard output is a terminal device and -c is not specified, use more(1) to paginate the
               output, just like man(1) would.

       -c      Copy the formatted manual pages to the standard output without using more(1) to paginate them.
               This is the default.  It can be specified to override -a.

       -I os=name
               Override the default operating system name for the mdoc(7) Os and for the man(7) TH macro.

       -K encoding
               Specify the input encoding.  The supported encoding arguments are us-ascii, iso-8859-1, and
               utf-8.  If not specified, autodetection uses the first match in the following list:

               1.   If the first three bytes of the input file are the UTF-8 byte order mark (BOM, 0xefbbbf),
                    input is interpreted as utf-8.

               2.   If the first or second line of the input file matches the emacs mode line format

                          .\" -*- [...;] coding: encoding; -*-

                    then input is interpreted according to encoding.

               3.   If the first non-ASCII byte in the file introduces a valid UTF-8 sequence, input is
                    interpreted as utf-8.

               4.   Otherwise, input is interpreted as iso-8859-1.
       -mdoc | -man
               With -mdoc, all input files are interpreted as mdoc(7).  With -man, all input files are
               interpreted as man(7).  By default, the input language is automatically detected for each file:
               if the the first macro is Dd or Dt, the mdoc(7) parser is used; otherwise, the man(7) parser is
               used.  With other arguments, -m is silently ignored.

       -O options
               Comma-separated output options.

       -T output
               Output format.  See Output Formats for available formats.  Defaults to -T locale.

       -W level
               Specify the minimum message level to be reported on the standard error output and to affect the
               exit status.  The level can be base, style, warning, error, or unsupp.  The base level
               automatically derives the operating system from the contents of the Os macro, from the -Ios
               command line option, or from the uname(3) return value.  The levels openbsd and netbsd are
               variants of base that bypass autodetection and request validation of base system conventions for
               a particular operating system.  The level all is an alias for base.  By default, mandoc is
               silent.  See EXIT STATUS and DIAGNOSTICS for details.

               The special option -W stop tells mandoc to exit after parsing a file that causes warnings or
               errors of at least the requested level.  No formatted output will be produced from that file.  If
               both a level and stop are requested, they can be joined with a comma, for example -W error,stop.

       file    Read input from zero or more files.  If unspecified, reads from stdin.  If multiple files are
               specified, mandoc will halt with the first failed parse.

       The options -fhklw are also supported and are documented in man(1).  In -f and -k mode, mandoc also
       supports the options -CMmOSs described in the apropos(1) manual.  The options -fkl are mutually exclusive
       and override each other.

   Output Formats
       The mandoc utility accepts the following -T arguments, which correspond to output modes:

       -T ascii     Produce 7-bit ASCII output.  See ASCII Output.

       -T html      Produce HTML5, CSS1, and MathML output.  See HTML Output.

       -T lint      Parse only: produce no output.  Implies -W all and redirects parser messages, which usually
                    appear on standard error output, to standard output.

       -T locale    Encode output using the current locale.  This is the default.  See Locale Output.

       -T man       Produce man(7) format output.  See Man Output.

       -T markdown
                    Produce output in markdown format.  See Markdown Output.

       -T pdf       Produce PDF output.  See PDF Output.

       -T ps        Produce PostScript output.  See PostScript Output.

       -T tree      Produce an indented parse tree.  See Syntax tree output.

       -T utf8      Encode output in the UTF-8 multi-byte format.  See UTF-8 Output.

       If multiple input files are specified, these will be processed by the corresponding filter in-order.

   ASCII Output
       Output produced by -T ascii is rendered in standard 7-bit ASCII documented in ascii(7).

       Font styles are applied by using back-spaced encoding such that an underlined character ‘c’ is rendered
       as ‘_\[bs]c’, where ‘\[bs]’ is the back-space character number 8.  Emboldened characters are rendered as
       ‘c\[bs]c’.

       The special characters documented in mandoc_char(7) are rendered best-effort in an ASCII equivalent.

       Output width is limited to 78 visible columns unless literal input lines exceed this limit.

       The following -O arguments are accepted:

       indent=indent
               The left margin for normal text is set to indent blank characters instead of the default of five
               for mdoc(7) and seven for man(7).  Increasing this is not recommended; it may result in degraded
               formatting, for example overfull lines or ugly line breaks.

       width=width
               The output width is set to width.

   HTML Output
       Output produced by -T html conforms to HTML5 using optional self-closing tags.  Default styles use only
       CSS1.  Equations rendered from eqn(7) blocks use MathML.

       The mandoc.css file documents style-sheet classes available for customising output.  If a style-sheet is
       not specified with -O style, -T html defaults to simple output (via an embedded style-sheet) readable in
       any graphical or text-based web browser.

       Special characters are rendered in decimal-encoded UTF-8.

       The following -O arguments are accepted:

       fragment
               Omit the <!DOCTYPE> declaration and the <html>, <head>, and <body> elements and only emit the
               subtree below the <body> element.  The style argument will be ignored.  This is useful when
               embedding manual content within existing documents.

       includes=fmt
               The string fmt, for example, ../src/%I.html, is used as a template for linked header files
               (usually via the In macro).  Instances of ‘%I’ are replaced with the include filename.  The
               default is not to present a hyperlink.

       man=fmt
               The string fmt, for example, ../html%S/%N.%S.html, is used as a template for linked manuals
               (usually via the Xr macro).  Instances of ‘%N’ and ‘%S’ are replaced with the linked manual's
               name and section, respectively.  If no section is included, section 1 is assumed.  The default is
               not to present a hyperlink.

       style=style.css
               The file style.css is used for an external style-sheet.  This must be a valid absolute or
               relative URI.

   Locale Output
       Locale-depending output encoding is triggered with -T locale.  This is the default.

       This option is not available on all systems: systems without locale support, or those whose internal
       representation is not natively UCS-4, will fall back to -T ascii.  See ASCII Output for font style
       specification and available command-line arguments.

   Man Output
       Translate input format into man(7) output format.  This is useful for distributing manual sources to
       legacy systems lacking mdoc(7) formatters.

       If mdoc(7) is passed as input, it is translated into man(7).  If the input format is man(7), the input is
       copied to the output, expanding any roff(7) so requests.  The parser is also run, and as usual, the -W
       level controls which DIAGNOSTICS are displayed before copying the input to the output.

   Markdown Output
       Translate mdoc(7) input to the markdown format conforming to John Gruber's 2004 specification:
             http://daringfireball.net/projects/markdown/syntax.text.
       The output also almost conforms to the CommonMark: http://commonmark.org/ specification.

       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.

       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 -T html directly.

       The man(7), tbl(7), and eqn(7) input languages are not supported by -T markdown output mode.

   PDF Output
       PDF-1.1 output may be generated by -T pdf.  See PostScript Output for -O arguments and defaults.

   PostScript Output
       PostScript "Adobe-3.0" Level-2 pages may be generated by -T ps.  Output pages default to letter sized and
       are rendered in the Times font family, 11-point.  Margins are calculated as 1/9 the page length and
       width.  Line-height is 1.4m.

       Special characters are rendered as in ASCII Output.

       The following -O arguments are accepted:

       paper=name
               The paper size name may be one of a3, a4, a5, legal, or letter.  You may also manually specify
               dimensions as NNxNN, width by height in millimetres.  If an unknown value is encountered, letter
               is used.

   UTF-8 Output
       Use -T utf8 to force a UTF-8 locale.  See Locale Output for details and options.

   Syntax tree output
       Use -T 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.

       The first paragraph shows meta data found in the mdoc(7) prologue, on the man(7) TH line, or the
       fallbacks used.

       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:

       1.   For macro nodes, the macro name; for text and tbl(7) nodes, the content.  There is a special format
            for eqn(7) nodes.
       2.   Node type (text, elem, block, head, body, body-end, tail, tbl, eqn).
       3.   Flags:
            -   An opening parenthesis if the node is an opening delimiter.
            -   An asterisk if the node starts a new input line.
            -   The input line number (starting at one).
            -   A colon.
            -   The input column number (starting at one).
            -   A closing parenthesis if the node is a closing delimiter.
            -   A full stop if the node ends a sentence.
            -   BROKEN if the node is a block broken by another block.
            -   NOSRC if the node is not in the input file, but automatically generated from macros.
            -   NOPRT if the node is not supposed to generate output for any output format.
       The following -O argument is accepted:

       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.

ENVIRONMENT

       MANPAGER  Any non-empty value of the environment variable MANPAGER is used instead of the standard
                 pagination program, more(1); see man(1) for details.  Only used if -a or -l is specified.

       PAGER     Specifies the pagination program to use when MANPAGER is not defined.  If neither PAGER nor
                 MANPAGER is defined, more(1) -s is used.  Only used if -a or -l is specified.

EXIT STATUS

       The mandoc utility exits with one of the following values, controlled by the message level associated
       with the -W option:

       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 level.
       1       At least one base system convention violation or style suggestion occurred, but no warning or
               error, and -W base or -W style was specified.
       2       At least one warning occurred, but no error, and -W warning or a lower level was requested.
       3       At least one parsing error occurred, but no unsupported feature was encountered, and -W error or
               a lower level was requested.
       4       At least one unsupported feature was encountered, and -W unsupp or a lower level was requested.
       5       Invalid command line arguments were specified.  No input files have been read.
       6       An operating system error occurred, for example exhaustion of memory, file descriptors, or
               process table entries.  Such errors cause mandoc to exit at once, possibly in the middle of
               parsing or formatting a file.

       Note that selecting -T lint output mode implies -W all.

EXAMPLES

       To page manuals to the terminal:

             $ mandoc -l mandoc.1 man.1 apropos.1 makewhatis.8

       To produce HTML manuals with mandoc.css as the style-sheet:

             $ mandoc -T html -O style=mandoc.css mdoc.7 > mdoc.7.html

       To check over a large set of manuals:

             $ mandoc -T lint `find /usr/src -name \*\.[1-9]`

       To produce a series of PostScript manuals for A4 paper:

             $ mandoc -T ps -O paper=a4 mdoc.7 man.7 > manuals.ps

       Convert a modern mdoc(7) manual to the older man(7) format, for use on systems lacking an mdoc(7) parser:

             $ mandoc -T man foo.mdoc > foo.man

DIAGNOSTICS

       Messages displayed by mandoc follow this format:

             mandoc: file:line:column: level: message: macro args (os)

       Line and column numbers start at 1.  Both are omitted for messages referring to an input file as a whole.
       Macro names and arguments are omitted where meaningless.  The 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 file and
       level fields.

       Message levels have the following meanings:

       unsupp   An input file uses unsupported low-level roff(7) features.  The output may be incomplete and/or
                misformatted, so using GNU troff instead of mandoc to process the file may be preferable.

       error    Indicates a risk of information loss or severe misformatting, in most cases caused by serious
                syntax errors.

       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.

       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 style level tries to reduce the probability
                that issues go unnoticed, so it may occasionally issue bogus suggestions.  Please use your good
                judgement to decide whether any particular style suggestion really justifies a change to the
                input file.

       base     A convertion 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 base level are printed with the more intuitive style level tag.

       Messages of the base, style, warning, error, and unsupp levels except those about non-existent or
       unreadable input files are hidden unless their level, or a lower level, is requested using a -W option or
       -T lint output mode.

       As indicated below, all base and some style checks are only performed if a specific operating system name
       occurs in the arguments of the -W command line option, of the Os macro, of the -Ios command line option,
       or, if neither are present, in the return value of the uname(3) function.

   Conventions for base system manuals
       Mdocdate found
       (mdoc, NetBSD) The Dd macro uses CVS Mdocdate keyword substitution, which is not supported by the NetBSD
       base system.  Consider using the conventional Month dd, yyyy format instead.

       Mdocdate missing
       (mdoc, OpenBSD) The Dd macro does not use CVS Mdocdate keyword substitution, but using it is
       conventionally expected in the OpenBSD base system.

       unknown architecture
       (mdoc, OpenBSD, NetBSD) The third argument of the Dt macro does not match any of the architectures this
       operating system is running on.

       operating system explicitly specified
       (mdoc, OpenBSD, NetBSD) The Os macro has an argument.  In the base system, it is conventionally left
       blank.

       RCS id missing
       (OpenBSD, NetBSD) The manual page lacks the comment line with the RCS identifier generated by CVS OpenBSD
       or NetBSD keyword substitution as conventionally used in these operating systems.

       referenced manual not found
       (mdoc) An Xr macro references a manual page that is not found in the base system.  The path to look for
       base system manuals is configurable at compile time and defaults to /usr/share/man: /usr/X11R6/man.

   Style suggestions
       legacy man(7) date format
       (mdoc) The Dd macro uses the legacy man(7) date format yyyy-dd-mm.  Consider using the conventional
       mdoc(7) date format Month dd, yyyy instead.

       lower case character in document title
       (mdoc, man) The title is still used as given in the Dt or TH macro.

       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.

       typo in section name
       (mdoc) Fuzzy string matching revealed that the argument of an Sh macro is similar, but not identical to a
       standard section name.

       unterminated quoted argument
       (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.

       useless macro
       (mdoc) A Bt, Tn, or Ud macro was found.  Simply delete it: it serves no useful purpose.

       consider using OS macro
       (mdoc) A string was found in plain text or in a Bx macro that could be represented using Ox, Nx, Fx, or
       Dx.

       errnos out of order
       (mdoc, NetBSD) The Er items in a Bl list are not in alphabetical order.

       duplicate errno
       (mdoc, NetBSD) A Bl list contains two consecutive It entries describing the same Er number.

       trailing delimiter
       (mdoc) The last argument of an Ex, Fo, Nd, Nm, Os, Sh, Ss, St, or Sx macro ends with a trailing
       delimiter.  This is usually bad style and often indicates typos.  Most likely, the delimiter can be
       removed.

       no blank before trailing delimiter
       (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.

       fill mode already enabled, skipping
       (man) A fi request occurs even though the document is still in fill mode, or already switched back to
       fill mode.  It has no effect.

       fill mode already disabled, skipping
       (man) An 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.

       function name without markup
       (mdoc) A word followed by an empty pair of parentheses occurs on a text line.  Consider using an Fn or Xr
       macro.

       whitespace at end of input line
       (mdoc, man, roff) Whitespace at the end of input lines is almost never semantically significant — but in
       the odd case where it might be, it is extremely confusing when reviewing and maintaining documents.

       bad comment style
       (roff) Comment lines start with a dot, a backslash, and a double-quote character.  The mandoc utility
       treats the line as a comment line even without the backslash, but leaving out the backslash might not be
       portable.

   Warnings related to the document prologue
       missing manual title, using UNTITLED
       (mdoc) A Dt macro has no arguments, or there is no Dt macro before the first non-prologue macro.

       missing manual title, using ""
       (man) There is no TH macro, or it has no arguments.

       missing manual section, using ""
       (mdoc, man) A Dt or TH macro lacks the mandatory section argument.

       unknown manual section
       (mdoc) The section number in a Dt line is invalid, but still used.

       missing date, using today's date
       (mdoc, man) The document was parsed as mdoc(7) and it has no Dd macro, or the Dd macro has no arguments
       or only empty arguments; or the document was parsed as man(7) and it has no TH macro, or the TH macro has
       less than three arguments or its third argument is empty.

       cannot parse date, using it verbatim
       (mdoc, man) The date given in a Dd or TH macro does not follow the conventional format.

       date in the future, using it anyway
       (mdoc, man) The date given in a Dd or TH macro is more than a day ahead of the current system time(3).

       missing Os macro, using ""
       (mdoc) The default or current system is not shown in this case.

       late prologue macro
       (mdoc) A Dd or Os macro occurs after some non-prologue macro, but still takes effect.

       prologue macros out of order
       (mdoc) The prologue macros are not given in the conventional order Dd, Dt, Os.  All three macros are used
       even when given in another order.

   Warnings regarding document structure
       .so is fragile, better use ln(1)
       (roff) Including files only works when the parser program runs with the correct current working
       directory.

       no document body
       (mdoc, man) The document body contains neither text nor macros.  An empty document is shown, consisting
       only of a header and a footer line.

       content before first section header
       (mdoc, man) Some macros or text precede the first Sh or SH section header.  The offending macros and text
       are parsed and added to the top level of the syntax tree, outside any section block.

       first section is not NAME
       (mdoc) The argument of the first Sh macro is not ‘NAME’.  This may confuse makewhatis(8) and apropos(1).

       NAME section without Nm before Nd
       (mdoc) The NAME section does not contain any Nm child macro before the first Nd macro.

       NAME section without description
       (mdoc) The NAME section lacks the mandatory Nd child macro.

       description not at the end of NAME
       (mdoc) The NAME section does contain an Nd child macro, but other content follows it.

       bad NAME section content
       (mdoc) The NAME section contains plain text or macros other than Nm and Nd.

       missing comma before name
       (mdoc) The NAME section contains an Nm macro that is neither the first one nor preceded by a comma.

       missing description line, using ""
       (mdoc) The Nd macro lacks the required argument.  The title line of the manual will end after the dash.

       description line outside NAME section
       (mdoc) An Nd macro appears outside the NAME section.  The arguments are printed anyway and the following
       text is used for apropos(1), but none of that behaviour is portable.

       sections out of conventional order
       (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.

       duplicate section title
       (mdoc) The same standard section title occurs more than once.

       unexpected section
       (mdoc) A standard section header occurs in a section of the manual where it normally isn't useful.

       cross reference to self
       (mdoc) An Xr macro refers to a name and section matching the section of the present manual page and a
       name mentioned in an Nm macro in the NAME or SYNOPSIS section, or in an Fn or Fo macro in the SYNOPSIS.
       Consider using Nm or Fn instead of Xr.

       unusual Xr order
       (mdoc) In the SEE ALSO section, an Xr macro with a lower section number follows one with a higher number,
       or two Xr macros referring to the same section are out of alphabetical order.

       unusual Xr punctuation
       (mdoc) In the SEE ALSO section, punctuation between two Xr macros differs from a single comma, or there
       is trailing punctuation after the last Xr macro.

       AUTHORS section without An macro
       (mdoc) An AUTHORS sections contains no An macros, or only empty ones.  Probably, there are author names
       lacking markup.

   Warnings related to macros and nesting
       obsolete macro
       (mdoc) See the mdoc(7) manual for replacements.

       macro neither callable nor escaped
       (mdoc) 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 ‘\&’.

       skipping paragraph macro
       In mdoc(7) documents, this happens
       -   at the beginning and end of sections and subsections
       -   right before non-compact lists and displays
       -   at the end of items in non-column, non-compact lists
       -   and for multiple consecutive paragraph macros.
       In man(7) documents, it happens
       -   for empty P, PP, and LP macros
       -   for IP macros having neither head nor body arguments
       -   for br or sp right after SH or SS

       moving paragraph macro out of list
       (mdoc) A list item in a Bl list contains a trailing paragraph macro.  The paragraph macro is moved after
       the end of the list.

       skipping no-space macro
       (mdoc) An input line begins with an Ns macro, or the next argument after an Ns macro is an isolated
       closing delimiter.  The macro is ignored.

       blocks badly nested
       (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 "Ao Bo Ac Bc" and "Ao Bq Ac".  In these examples, Ac breaks Bo and Bq,
       respectively.

       nested displays are not portable
       (mdoc) A Bd, D1, or Dl display occurs nested inside another Bd display.  This works with mandoc, but
       fails with most other implementations.

       moving content out of list
       (mdoc) A Bl list block contains text or macros before the first It macro.  The offending children are
       moved before the beginning of the list.

       first macro on line
       Inside a Bl -column list, a Ta macro occurs as the first macro on a line, which is not portable.

       line scope broken
       (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.

   Warnings related to missing arguments
       skipping empty request
       (roff, eqn) The macro name is missing from a macro definition request, or an eqn(7) control statement or
       operation keyword lacks its required argument.

       conditional request controls empty scope
       (roff) A conditional request is only useful if any of the following follows it on the same logical input
       line:
       -   The ‘\{’ keyword to open a multi-line scope.
       -   A request or macro or some text, resulting in a single-line scope.
       -   The immediate end of the logical line without any intervening whitespace, resulting in next-line
           scope.
       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 ‘\’ 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
       el clause.

       skipping empty macro
       (mdoc) The indicated macro has no arguments and hence no effect.

       empty block
       (mdoc, man) A Bd, Bk, Bl, D1, Dl, MT, RS, or UR block contains nothing in its body and will produce no
       output.

       empty argument, using 0n
       (mdoc) The required width is missing after Bd or Bl -offset or -width.

       missing display type, using -ragged
       (mdoc) The Bd macro is invoked without the required display type.

       list type is not the first argument
       (mdoc) In a Bl macro, at least one other argument precedes the type argument.  The mandoc utility copes
       with any argument order, but some other mdoc(7) implementations do not.

       missing -width in -tag list, using 8n
       (mdoc) Every Bl macro having the -tag argument requires -width, too.

       missing utility name, using ""
       (mdoc) The Ex -std macro is called without an argument before Nm has first been called with an argument.

       missing function name, using ""
       (mdoc) The Fo macro is called without an argument.  No function name is printed.

       empty head in list item
       (mdoc) In a Bl -diag, -hang, -inset, -ohang, or -tag list, an It macro lacks the required argument.  The
       item head is left empty.

       empty list item
       (mdoc) In a Bl -bullet, -dash, -enum, or -hyphen list, an It block is empty.  An empty list item is
       shown.

       missing argument, using next line
       (mdoc) An It macro in a Bd -column list has no arguments.  While mandoc uses the text or macros of the
       following line, if any, for the cell, other formatters may misformat the list.

       missing font type, using \fR
       (mdoc) A Bf macro has no argument.  It switches to the default font.

       unknown font type, using \fR
       (mdoc) The Bf argument is invalid.  The default font is used instead.

       nothing follows prefix
       (mdoc) A 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.

       empty reference block
       (mdoc) An Rs macro is immediately followed by an Re macro on the next input line.  Such an empty block
       does not produce any output.

       missing section argument
       (mdoc) An Xr macro lacks its second, section number argument.  The first argument, i.e. the name, is
       printed, but without subsequent parentheses.

       missing -std argument, adding it
       (mdoc) An Ex or Rv macro lacks the required -std argument.  The mandoc utility assumes -std even when it
       is not specified, but other implementations may not.

       missing option string, using ""
       (man) The OP macro is invoked without any argument.  An empty pair of square brackets is shown.

       missing resource identifier, using ""
       (man) The MT or UR macro is invoked without any argument.  An empty pair of angle brackets is shown.

       missing eqn box, using ""
       (eqn) A diacritic mark or a binary operator is found, but there is nothing to the left of it.  An empty
       box is inserted.

   Warnings related to bad macro arguments
       duplicate argument
       (mdoc) A Bd or Bl macro has more than one -compact, more than one -offset, or more than one -width
       argument.  All but the last instances of these arguments are ignored.

       skipping duplicate argument
       (mdoc) An An macro has more than one -split or -nosplit argument.  All but the first of these arguments
       are ignored.

       skipping duplicate display type
       (mdoc) A Bd macro has more than one type argument; the first one is used.

       skipping duplicate list type
       (mdoc) A Bl macro has more than one type argument; the first one is used.

       skipping -width argument
       (mdoc) A Bl -column, -diag, -ohang, -inset, or -item list has a -width argument.  That has no effect.

       wrong number of cells
       In a line of a Bl -column list, the number of tabs or 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.

       unknown AT&T UNIX version
       (mdoc) An At macro has an invalid argument.  It is used verbatim, with "AT&T UNIX " prefixed to it.

       comma in function argument
       (mdoc) An argument of an Fa or Fn macro contains a comma; it should probably be split into two arguments.

       parenthesis in function name
       (mdoc) The first argument of an Fc or Fn macro contains an opening or closing parenthesis; that's
       probably wrong, parentheses are added automatically.

       unknown library name
       (mdoc, not on OpenBSD) An Lb macro has an unknown name argument and will be rendered as "library name".

       invalid content in Rs block
       (mdoc) An Rs block contains plain text or non-% macros.  The bogus content is left in the syntax tree.
       Formatting may be poor.

       invalid Boolean argument
       (mdoc) An Sm macro has an argument other than on or off.  The invalid argument is moved out of the macro,
       which leaves the macro empty, causing it to toggle the spacing mode.

       unknown font, skipping request
       (man, tbl) A roff(7) ft request or a tbl(7) f layout modifier has an unknown font argument.

       odd number of characters in request
       (roff) A tr request contains an odd number of characters.  The last character is mapped to the blank
       character.

   Warnings related to plain text
       blank line in fill mode, using .sp
       (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 replaced with sp requests.

       tab in filled text
       (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.

       new sentence, new line
       (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.

       invalid escape sequence
       (roff) An escape sequence has an invalid opening argument delimiter, lacks the closing argument
       delimiter, or the argument has too few characters.  If the argument is incomplete, \* and \n expand to an
       empty string, \B to the digit ‘0’, and \w to the length of the incomplete argument.  All other invalid
       escape sequences are ignored.

       undefined string, using ""
       (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.

   Warnings related to tables
       tbl line starts with span
       (tbl) The first cell in a table layout line is a horizontal span (‘s’).  Data provided for this cell is
       ignored, and nothing is printed in the cell.

       tbl column starts with span
       (tbl) The first line of a table layout specification requests a vertical span (‘^’).  Data provided for
       this cell is ignored, and nothing is printed in the cell.

       skipping vertical bar in tbl layout
       (tbl) A table layout specification contains more than two consecutive vertical bars.  A double bar is
       printed, all additional bars are discarded.

   Errors related to tables
       non-alphabetic character in tbl options
       (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.

       skipping unknown tbl option
       (tbl) The table options line contains a string of letters that does not match any known option name.  The
       word is ignored.

       missing tbl option argument
       (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.

       wrong tbl option argument size
       (tbl) A table option argument contains an invalid number of characters.  Both the option and the argument
       are ignored.

       empty tbl layout
       (tbl) A table layout specification is completely empty, specifying zero lines and zero columns.  As a
       fallback, a single left-justified column is used.

       invalid character in tbl layout
       (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.

       unmatched parenthesis in tbl layout
       (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.

       tbl without any data cells
       (tbl) A table does not contain any data cells.  It will probably produce no output.

       ignoring data in spanned tbl cell
       (tbl) A table cell is marked as a horizontal span (‘s’) or vertical span (‘^’) in the table layout, but
       it contains data.  The data is ignored.

       ignoring extra tbl data cells
       (tbl) A data line contains more cells than the corresponding layout line.  The data in the extra cells is
       ignored.

       data block open at end of tbl
       (tbl) A data block is opened with T{, but never closed with a matching T}.  The remaining data lines of
       the table are all put into one cell, and any remaining cells stay empty.

   Errors related to roff, mdoc, and man code
       duplicate prologue macro
       (mdoc) One of the prologue macros occurs more than once.  The last instance overrides all previous ones.

       skipping late title macro
       (mdoc) The 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 mandoc, traditional semantics is preserved.  The late macro is discarded
       including its arguments.

       input stack limit exceeded, infinite loop?
       (roff) Explicit recursion limits are implemented for the following features, in order to prevent infinite
       loops:
       -   expansion of nested escape sequences including expansion of strings and number registers,
       -   expansion of nested user-defined macros,
       -   and so file inclusion.
       When a limit is hit, the output is incorrect, typically losing some content, but the parser can continue.

       skipping bad character
       (mdoc, man, roff) The input file contains a byte that is not a printable ascii(7) character.  The message
       mentions the character number.  The offending byte is replaced with a question mark (‘?’).  Consider
       editing the input file to replace the byte with an ASCII transliteration of the intended character.

       skipping unknown macro
       (mdoc, man, roff) The first identifier on a request or macro line is neither recognized as a roff(7)
       request, nor as a user-defined macro, nor, respectively, as an mdoc(7) or man(7) macro.  It may be
       mistyped or unsupported.  The request or macro is discarded including its arguments.

       skipping insecure request
       (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.

       skipping item outside list
       (mdoc, eqn) An It macro occurs outside any Bl list, or an eqn(7) above delimiter occurs outside any pile.
       It is discarded including its arguments.

       skipping column outside column list
       (mdoc) A Ta macro occurs outside any Bl -column block.  It is discarded including its arguments.

       skipping end of block that is not open
       (mdoc, man, eqn, tbl, roff) Various syntax elements can only be used to explicitly close blocks that have
       previously been opened.  An mdoc(7) block closing macro, a man(7) ME, RE or UE macro, an eqn(7) right
       delimiter or closing brace, or the end of an equation, table, or roff(7) conditional request is
       encountered but no matching block is open.  The offending request or macro is discarded.

       fewer RS blocks open, skipping
       (man) The RE macro is invoked with an argument, but less than the specified number of RS blocks is open.
       The RE macro is discarded.

       inserting missing end of block
       (mdoc, tbl) Various 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.

       appending missing end of block
       (mdoc, man, eqn, tbl, roff) At the end of the document, an explicit mdoc(7) block, a man(7) next-line
       scope or MT, RS or UR block, an equation, table, or roff(7) conditional or ignore block is still open.
       The open block is closed implicitly.

       escaped character not allowed in a name
       (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 am, as, de, ds, nr, or rr request, or any argument of an rm request, or the name of
       a request or user defined macro being called, is terminated by an escape sequence.  In the cases of as,
       ds, and nr, the request has no effect at all.  In the cases of am, de, rr, and 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.

       NOT IMPLEMENTED: Bd -file
       (mdoc) For security reasons, the Bd macro does not support the -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.

       skipping display without arguments
       (mdoc) A 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.

       missing list type, using -item
       (mdoc) A Bl macro fails to specify the list type.

       argument is not numeric, using 1
       (roff) The argument of a ce request is not a number.

       missing manual name, using ""
       (mdoc) The first call to Nm, or any call in the NAME section, lacks the required argument.

       uname(3) system call failed, using UNKNOWN
       (mdoc) The Os macro is called without arguments, and the uname(3) system call failed.  As a workaround,
       mandoc can be compiled with -DOSNAME="\"string\"".

       unknown standard specifier
       (mdoc) An St macro has an unknown argument and is discarded.

       skipping request without numeric argument
       (roff, eqn) An it request or an eqn(7) size or gsize statement has a non-numeric or negative argument or
       no argument at all.  The invalid request or statement is ignored.

       NOT IMPLEMENTED: .so with absolute path or ".."
       (roff) For security reasons, mandoc allows 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.  mandoc only shows the path as it appears behind so.

       .so request failed
       (roff) Servicing a so request requires reading an external file, but the file could not be opened.
       mandoc only shows the path as it appears behind so.

       skipping all arguments
       (mdoc, man, eqn, roff) An mdoc(7) Bt, Ed, Ef, Ek, El, Lp, Pp, Re, Rs, or Ud macro, an It macro in a list
       that don't support item heads, a man(7) LP, P, or PP macro, an eqn(7) EQ or EN macro, or a roff(7) br,
       fi, or nf request or ‘..’  block closing request is invoked with at least one argument.  All arguments
       are ignored.

       skipping excess arguments
       (mdoc, man, roff) A macro or request is invoked with too many arguments:
         -   Fo, MT, PD, RS, UR, ft, or sp with more than one argument
         -   An with another argument after -split or -nosplit
         -   RE with more than one argument or with a non-integer argument
         -   OP or a request of the de family with more than two arguments
         -   Dt with more than three arguments
         -   TH with more than five arguments
         -   Bd, Bk, or Bl with invalid arguments
       The excess arguments are ignored.

   Unsupported features
       input too large
       (mdoc, man) Currently, mandoc 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.

       unsupported control character
       (roff) An ASCII control character supported by other roff(7) implementations but not by mandoc was found
       in an input file.  It is replaced by a question mark.

       unsupported roff request
       (roff) An input file contains a roff(7) request supported by GNU troff or Heirloom troff but not by
       mandoc, and it is likely that this will cause information loss or considerable misformatting.

       eqn delim option in tbl
       (eqn, tbl) The options line of a table defines equation delimiters.  Any equation source code contained
       in the table will be printed unformatted.

       unsupported table layout modifier
       (tbl) A table layout specification contains an ‘m’ modifier.  The modifier is discarded.

       ignoring macro in table
       (tbl, mdoc, man) A table contains an invocation of an mdoc(7) or man(7) macro or of an undefined macro.
       The macro is ignored, and its arguments are handled as if they were a text line.

SEE ALSO

       apropos(1), man(1), eqn(7), man(7), mandoc_char(7), mdoc(7), roff(7), tbl(7)

HISTORY

       The mandoc utility first appeared in OpenBSD 4.8.  The option -I appeared in OpenBSD 5.2, and
       -aCcfhKklMSsw in OpenBSD 5.7.

AUTHORS

       The mandoc utility was written by Kristaps Dzonsons <kristaps@bsd.lv> and is maintained by Ingo Schwarze
       <schwarze@openbsd.org>.