mandoc/mandoc.1 - diff

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Up to [cvsweb.bsd.lv] / mandoc

Diff for /mandoc/mandoc.1 between version 1.222 and 1.260

version 1.222, 2018/03/16 15:05:44

version 1.260, 2022/06/07 09:54:40

Line 1

.\" $Id$

.\"

.\" Permission to use, copy, modify, and distribute this software for any

.\" purpose with or without fee is hereby granted, provided that the above

Line 34

.Sh DESCRIPTION

The

.Nm

utility formats

utility formats manual pages for display.

.Ux

manual pages for display.

.Pp

By default,

.Nm

Line 54 The options are as follows:

Line 52 The options are as follows:

If the standard output is a terminal device and

.Fl c

is not specified, use

.Xr more 1

.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 more 1

.Xr less 1

to paginate them.

This is the default.

It can be specified to override

Line 132 With other arguments,

Line 130 With other arguments,

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

Output format.

Select the output format.

See

Supported values for the

.Sx Output Formats

.Ar output

for available formats.

argument are

Defaults to

.Cm ascii ,

.Fl T Cm locale .

.Cm html ,

the default of

.Cm locale ,

.Cm man ,

.Cm markdown ,

.Cm pdf ,

.Cm ps ,

.Cm tree ,

and

.Cm utf8 .

.Pp

The special

.Fl T Cm lint

mode only parses the input and produces no output.

It implies

.Fl W Cm all

and redirects parser messages, which usually appear on standard

error output, to standard output.

.It Fl W Ar level

Specify the minimum message

.Ar level

Line 196 and

Line 213 and

are requested, they can be joined with a comma, for example

.Fl W Cm error , Ns Cm stop .

.It Ar file

Read input from zero or more files.

Read from the given input file.

If unspecified, reads from stdin.

If multiple files are specified, they are processed in the given order.

If multiple files are specified,

If unspecified,

.Nm

will halt with the first failed parse.

reads from standard input.

.El

.Pp

The options

.Fl fhklw

are also supported and are documented in man(1).

are also supported and are documented in

.Xr man 1 .

.Fl f

and

Line 220 manual.

Line 238 manual.

The options

.Fl fkl

are mutually exclusive and override each other.

.Ss Output Formats

The

.Nm

utility accepts the following

.Fl T

arguments, which correspond to output modes:

.Bl -tag -width "-T markdown"

.It Fl T Cm ascii

Produce 7-bit ASCII output.

See

.Sx ASCII Output .

.It Fl T Cm html

Produce HTML5, CSS1, and MathML output.

See

.Sx HTML Output .

.It Fl T Cm lint

Parse only: produce no output.

Implies

.Fl W Cm all

and redirects parser messages, which usually appear

on standard error output, to standard output.

.It Fl T Cm locale

Encode output using the current locale.

This is the default.

See

.Sx Locale Output .

.It Fl T Cm man

Produce

.Xr man 7

format output.

See

.Sx Man Output .

.It Fl T Cm markdown

Produce output in

.Sy markdown

format.

See

.Sx Markdown Output .

.It Fl T Cm pdf

Produce PDF output.

See

.Sx PDF Output .

.It Fl T Cm ps

Produce PostScript output.

See

.Sx PostScript Output .

.It Fl T Cm tree

Produce an indented parse tree.

See

.Sx Syntax tree output .

.It Fl T Cm utf8

Encode output in the UTF\-8 multi-byte format.

See

.Sx UTF\-8 Output .

.El

.Pp

If multiple input files are specified, these will be processed by the

corresponding filter in-order.

.Ss ASCII Output

Output produced by

Use

.Fl T Cm ascii

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

Font styles are applied by using back-spaced encoding such that an

underlined character

Line 294 where

Line 257 where

is the back-space character number 8.

Emboldened characters are rendered as

.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

The special characters documented in

.Xr mandoc_char 7

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

Output width is limited to 78 visible columns unless literal input lines

exceed this limit.

.Pp

The following

.Fl O

arguments are accepted:

Line 315 and seven for

Line 293 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.

Specifically, this suppresses the two additional blank lines near the

This prints the operating system name rather than the page title

top and the bottom of each page, and it implies

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

The output width is set to

.Ar width .

.Ar width

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

.Ss HTML Output

Output produced by

Line 342 Equations rendered from

Line 347 Equations rendered from

.Xr eqn 7

blocks use MathML.

.Pp

The

The file

.Pa mandoc.css

.Pa /usr/share/misc/mandoc.css

file documents style-sheet classes available for customising output.

documents style-sheet classes available for customising output.

If a style-sheet is not specified with

.Fl O Cm style ,

.Fl T Cm html

Line 352 defaults to simple output (via an embedded style-sheet

Line 357 defaults to simple output (via an embedded style-sheet

readable in any graphical or text-based web

browser.

.Pp

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

Non-ASCII characters are rendered

as hexadecimal Unicode character references.

.Pp

The following

.Fl O

Line 378 Instances of

Line 384 Instances of

are replaced with the include filename.

The default is not to present a

hyperlink.

.It Cm man Ns = Ns Ar fmt

.It Cm man Ns = Ns Ar fmt Ns Op ; Ns Ar fmt

The string

.Ar fmt ,

for example,

Line 394 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.

The default is not to

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

The file

.Ar style.css

is used for an external style-sheet.

This must be a valid absolute or

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

.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

.Ss Locale Output

Locale-depending output encoding is triggered with

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 ,

.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 .

This is the default.

.Pp

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

.Fl T Cm ascii .

See

.Sx ASCII Output

for font style specification and available command-line arguments.

.Ss Man Output

Translate input format into

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 mdoc 7

is passed as input, it is translated into

.Xr man 7 .

If the input format is

.Xr man 7 ,

the input is copied to the output, expanding any

the input is copied to the output.

.Xr roff 7

.Ic so

requests.

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

Translate

Use

.Fl T Cm markdown

to translate

.Xr mdoc 7

input to the

input to the markdown format conforming to

.Sy markdown

.Lk https://daringfireball.net/projects/markdown/syntax.text\

format conforming to

.Lk http://daringfireball.net/projects/markdown/syntax.text\

"John Gruber's 2004 specification" .

The output also almost conforms to the

.Lk http://commonmark.org/ CommonMark

.Lk https://commonmark.org/ CommonMark

specification.

.Pp

The character set used for the markdown output is ASCII.

Line 513 If an unknown value is encountered,

Line 557 If an unknown value is encountered,

.Ar letter

is used.

.El

.Ss UTF\-8 Output

.Ss UTF-8 Output

Use

.Fl T Cm utf8

to force a UTF\-8 locale.

to force text output in UTF-8 multi-byte character encoding,

ignoring the

.Xr locale 1

settings in the environment.

See

.Sx Locale Output

.Sx ASCII Output

for details and options.

regarding font styles and

.Fl O

arguments.

.Pp

On operating systems lacking locale or wide character support, and

on those where the internal character representation is not UCS-4,

.Nm

always falls back to

.Sx ASCII Output .

.Ss Syntax tree output

Use

.Fl T Cm tree

Line 588 Meta data is not available in this case.

Line 643 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 more 1 ;

.Xr less 1 ;

see

.Xr man 1

for details.

Line 606 Specifies the pagination program to use when

Line 668 Specifies the pagination program to use when

.Ev MANPAGER

is not defined.

If neither PAGER nor MANPAGER is defined,

.Xr more 1

.Xr less 1

.Fl s

is used.

Only used if

.Fl a

Line 662 No input files have been read.

Line 723 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 cause

Such errors may cause

.Nm

to exit at once, possibly in the middle of parsing or formatting a file.

.El

Line 674 output mode implies

Line 735 output mode implies

.Sh EXAMPLES

To page manuals to the terminal:

.Pp

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

.Dl $ mandoc -a mandoc.1 man.1 apropos.1 makewhatis.8

.Pp

To produce HTML manuals with

.Pa mandoc.css

.Pa /usr/share/misc/mandoc.css

as the style-sheet:

.Pp

.Dl $ mandoc \-T html -O style=mandoc.css mdoc.7 \*(Gt mdoc.7.html

.Dl $ mandoc \-T html -O style=/usr/share/misc/mandoc.css mdoc.7 > mdoc.7.html

.Pp

To check over a large set of manuals:

.Pp

Line 688 To check over a large set of manuals:

Line 749 To check over a large set of manuals:

.Pp

To produce a series of PostScript manuals for A4 paper:

.Pp

.Dl $ mandoc \-T ps \-O paper=a4 mdoc.7 man.7 \*(Gt manuals.ps

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

.Pp

Convert a modern

.Xr mdoc 7

Line 698 format, for use on systems lacking an

Line 759 format, for use on systems lacking an

.Xr mdoc 7

parser:

.Pp

.Dl $ mandoc \-T man foo.mdoc \*(Gt foo.man

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

.Sh DIAGNOSTICS

Messages displayed by

.Nm

follow this format:

.Bd -ragged -offset indent

.Nm :

.Ar file : Ns Ar line : Ns Ar column : level : message : macro args

.Ar file : Ns Ar line : Ns Ar column : level : message : macro arguments

.Pq Ar os

.Ed

.Pp

Line and column numbers start at 1.

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.

Macro names and arguments are omitted where meaningless.

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

.Ar os

operating system specifier is omitted for messages that are relevant

Line 726 fields.

Line 803 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

Line 751 message levels, the

Line 835 message levels, the

.Cm 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

Use your judgement to decide whether any particular

.Cm style

suggestion really justifies a change to the input file.

.It Cm base

Line 774 Messages of the

Line 858 Messages of the

.Cm error ,

and

.Cm unsupp

levels except those about non-existent or unreadable input files

levels are hidden unless their level, or a lower level, is requested using a

are hidden unless their level, or a lower level, is requested using a

.Fl W

option or

.Fl T Cm lint

Line 839 generated by CVS

Line 922 generated by CVS

.Ic NetBSD

keyword substitution as conventionally used in these operating systems.

.It Sy "referenced manual not found"

.Pq mdoc

.Ic \&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

.Pa /usr/share/man : /usr/X11R6/man .

.El

.Ss Style suggestions

.Bl -ohang

Line 863 Consider using the conventional

Line 938 Consider using the conventional

date format

.Dq "Month dd, yyyy"

instead.

.It Sy "normalizing date format to" : No ...

.Pq mdoc , man

The

.Ic \&Dd

.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

Line 923 list contains two consecutive

Line 1008 list contains two consecutive

entries describing the same

.Ic \&Er

number.

.It Sy "referenced manual not found"

.Pq mdoc

.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

Line 952 An

Line 1066 An

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

Line 1005 macro lacks the mandatory section argument.

Line 1122 macro lacks the mandatory section argument.

The section number in a

.Ic \&Dt

line is invalid, but still used.

.It Sy "missing date, using today's date"

.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

.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

Line 1606 or

Line 1737 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

Line 1617 request or a

Line 1754 request or a

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

Line 1632 The meaning of blank input lines is only well-defined

Line 1778 The meaning of blank input lines is only well-defined

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

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:

Line 1648 it is hard to predict which tab stop position the tab

Line 1797 it is hard to predict which tab stop position the tab

.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"

.It Sy "invalid escape sequence argument"

.Pq roff

An escape sequence has an invalid opening argument delimiter, lacks the

The argument of an escape sequence is of an invalid form.

closing argument delimiter, or the argument has too few characters.

Invalid escape sequences are ignored.

If the argument is incomplete,

.It Sy "undefined escape, printing literally"

.Ic \e*

.Pq roff

and

In an escape sequence, the first character

.Ic \en

right after the leading backslash is invalid.

expand to an empty string,

That character is printed literally,

.Ic \eB

which is equivalent to ignoring the backslash.

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 string, using \(dq\(dq"

.Pq roff

If a string is used without being defined before,

Line 1727 The invalid character is discarded.

Line 1870 The invalid character is discarded.

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.

Line 1807 or

Line 1954 or

macro.

It may be mistyped or unsupported.

The request or macro is discarded including its arguments.

.It Sy "skipping request outside macro"

.Pq roff

.Ic shift

.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

Line 1916 When parsing for a request or a user-defined macro nam

Line 2070 When parsing for a request or a user-defined macro nam

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

.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

Line 1944 macro fails to specify the list type.

Line 2113 macro fails to specify the list type.

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

Line 1978 or

Line 2161 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,

Line 2082 with invalid arguments

Line 2272 with invalid arguments

.El

The excess arguments are ignored.

.El

.Ss "Errors related to escape sequences"

.Bl -ohang

.It Sy "incomplete escape sequence"

.Pq roff

The end of the input line is encountered

while parsing the argument of an escape sequence.

In this case,

.Ic \e*

and

.Ic \en

expand to an empty string,

.Ic \eB

to the digit

.Sq 0 ,

and

.Ic \ew

to the length of the incomplete argument.

All other incomplete escape sequences are ignored.

.It Sy "invalid special character"

.Pq roff

A special character escape sequence is invalid,

for example a Unicode sequence pointing to a surrogate

or beyond the Unicode range, a \e[char...] escape sequence

representing a control character or pointing beyond the

.Vt unsigned char

range, or an invalid variable-length form

of a single-byte character escape sequence, for example writing

.Qq \e[e]

.Qq \e[~]

instead of

.Qq \ee

.Qq \e~ ,

respectively.

The escape sequence is ignored.

.It Sy "unknown special character"

.Pq roff

The name given in a special character escape sequence is not known to

.Nm .

The escape sequence is ignored.

.It Sy "invalid escape argument delimiter"

.Pq roff

An escape sequence that expects a numerical argument

attempts to employ one of the characters

.Qq " %&()*+-./0123456789:<=>"

as an argument delimiter.

The escape sequence is ignored including the invalid opening delimiter

and the rest of the argument may appear as output text.

While various charcters can be used as argument delimiters,

using the apostrophe-quote character

.Pq Sq \(aq

is recommended for readability and robustness.

.El

.Ss Unsupported features

.Bl -ohang

.It Sy "input too large"

Line 2100 implementations but not by

Line 2344 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

Line 2127 or

Line 2378 or

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

.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

.Xr apropos 1 ,

CVSweb