If messages are shown and output is printed without a pager, display

[mandoc.git] / mandoc.1

diff --git a/mandoc.1 b/mandoc.1
index 3bd329a77884cfd7fc50ff174b49f7cd53a99518..298d5dc706102eef370d4b79a9c00592b3587a67 100644 (file)
--- a/mandoc.1
+++ b/mandoc.1
@@ -1,7 +1,7 @@
-.\"    $Id: mandoc.1,v 1.222 2018/03/16 15:05:44 schwarze Exp $
+.\"    $Id: mandoc.1,v 1.240 2019/07/10 19:39:01 schwarze Exp $

 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>

-.\" Copyright (c) 2012, 2014-2018 Ingo Schwarze <schwarze@openbsd.org>
+.\" Copyright (c) 2012, 2014-2019 Ingo Schwarze <schwarze@openbsd.org>

 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
 .\" purpose with or without fee is hereby granted, provided that the above


@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"

-.Dd $Mdocdate: March 16 2018 $
+.Dd $Mdocdate: July 10 2019 $

 .Dt MANDOC 1
 .Os
 .Sh NAME
 .Dt MANDOC 1
 .Os
 .Sh NAME


@@ -34,9 +34,7 @@
 .Sh DESCRIPTION
 The
 .Nm
 .Sh DESCRIPTION
 The
 .Nm

-utility formats
-.Ux
-manual pages for display.
+utility formats manual pages for display.

 .Pp
 By default,
 .Nm
 .Pp
 By default,
 .Nm


@@ -132,13 +130,32 @@ With other arguments,
 is silently ignored.
 .It Fl O Ar options
 Comma-separated output options.
 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
 .It Fl T Ar output

-Output format.
-See
-.Sx Output Formats
-for available formats.
-Defaults to
-.Fl T Cm locale .
+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
+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
 .It Fl W Ar level
 Specify the minimum message
 .Ar level


@@ -196,16 +213,17 @@ and
 are requested, they can be joined with a comma, for example
 .Fl W Cm error , Ns Cm stop .
 .It Ar file
 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.
-If unspecified, reads from stdin.
-If multiple files are specified,
+Read from the given input file.
+If multiple files are specified, they are processed in the given order.
+If unspecified,

 .Nm
 .Nm

-will halt with the first failed parse.
+reads from standard input.

 .El
 .Pp
 The options
 .Fl fhklw
 .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 .

 In
 .Fl f
 and
 In
 .Fl f
 and


@@ -220,69 +238,14 @@ manual.
 The options
 .Fl fkl
 are mutually exclusive and override each other.
 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
 .Ss ASCII Output

-Output produced by
+Use

 .Fl T Cm ascii
 .Fl T Cm ascii

-is rendered in standard 7-bit ASCII documented in
-.Xr ascii 7 .
+to force text output in 7-bit ASCII character encoding documented in the
+.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
 .Pp
 Font styles are applied by using back-spaced encoding such that an
 underlined character


@@ -294,13 +257,28 @@ where
 is the back-space character number 8.
 Emboldened characters are rendered as
 .Sq c Ns \e[bs] Ns c .
 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.
 .Pp
 The special characters documented in
 .Xr mandoc_char 7
 are rendered best-effort in an ASCII equivalent.

-.Pp
-Output width is limited to 78 visible columns unless literal input lines
-exceed this limit.
+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
 The following
 .Fl O
 .Pp
 The following
 .Fl O


@@ -315,6 +293,8 @@ 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.
 .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
 .It Cm mdoc
 Format
 .Xr man 7


@@ -329,9 +309,34 @@ One useful application is for checking that
 output formats in the same way as the
 .Xr mdoc 7
 source it was generated from.
 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
 .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
 .El
 .Ss HTML Output
 Output produced by


@@ -342,9 +347,9 @@ Equations rendered from
 .Xr eqn 7
 blocks use MathML.
 .Pp
 .Xr eqn 7
 blocks use MathML.
 .Pp

-The
-.Pa mandoc.css
-file documents style-sheet classes available for customising output.
+The file
+.Pa /usr/share/misc/mandoc.css
+documents style-sheet classes available for customising output.

 If a style-sheet is not specified with
 .Fl O Cm style ,
 .Fl T Cm html
 If a style-sheet is not specified with
 .Fl O Cm style ,
 .Fl T Cm html


@@ -352,7 +357,8 @@ defaults to simple output (via an embedded style-sheet)
 readable in any graphical or text-based web
 browser.
 .Pp
 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
 .Pp
 The following
 .Fl O


@@ -378,7 +384,7 @@ Instances of
 are replaced with the include filename.
 The default is not to present a
 hyperlink.
 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,
 The string
 .Ar fmt ,
 for example,


@@ -394,27 +400,43 @@ 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.
 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 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 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
 .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 ,
+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 .
 .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
 .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
 .Xr man 7
 output format.
 This is useful for distributing manual sources to legacy systems


@@ -422,11 +444,7 @@ lacking
 .Xr mdoc 7
 formatters.
 .Pp
 .Xr mdoc 7
 formatters.
 .Pp

-If
-.Xr mdoc 7
-is passed as input, it is translated into
-.Xr man 7 .
-If the input format is
+If the input format of a file is

 .Xr man 7 ,
 the input is copied to the output, expanding any
 .Xr roff 7
 .Xr man 7 ,
 the input is copied to the output, expanding any
 .Xr roff 7


@@ -438,11 +456,11 @@ level controls which
 .Sx DIAGNOSTICS
 are displayed before copying the input to the output.
 .Ss Markdown Output
 .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
 .Xr mdoc 7

-input to the
-.Sy markdown
-format conforming to
+input to the markdown 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://daringfireball.net/projects/markdown/syntax.text\
  "John Gruber's 2004 specification" .
 The output also almost conforms to the


@@ -513,13 +531,24 @@ If an unknown value is encountered,
 .Ar letter
 is used.
 .El
 .Ar letter
 is used.
 .El

-.Ss UTF\-8 Output
+.Ss UTF-8 Output

 Use
 .Fl T Cm utf8
 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
 See

-.Sx Locale Output
-for details and options.
+.Sx ASCII Output
+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
 .Ss Syntax tree output
 Use
 .Fl T Cm tree


@@ -588,6 +617,13 @@ Meta data is not available in this case.
 .El
 .Sh ENVIRONMENT
 .Bl -tag -width MANPAGER
 .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
 .It Ev MANPAGER
 Any non-empty value of the environment variable
 .Ev MANPAGER


@@ -662,7 +698,7 @@ No input files have been read.
 .It 6
 An operating system error occurred, for example exhaustion
 of memory, file descriptors, or process table entries.
 .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
 .Nm
 to exit at once, possibly in the middle of parsing or formatting a file.
 .El


@@ -677,10 +713,10 @@ To page manuals to the terminal:
 .Dl $ mandoc -l mandoc.1 man.1 apropos.1 makewhatis.8
 .Pp
 To produce HTML manuals with
 .Dl $ mandoc -l 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
 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
 .Pp
 To check over a large set of manuals:
 .Pp


@@ -688,7 +724,7 @@ To check over a large set of manuals:
 .Pp
 To produce a series of PostScript manuals for A4 paper:
 .Pp
 .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
 .Pp
 Convert a modern
 .Xr mdoc 7


@@ -698,20 +734,36 @@ format, for use on systems lacking an
 .Xr mdoc 7
 parser:
 .Pp
 .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 :
 .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
 .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.
 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
 The
 .Ar os
 operating system specifier is omitted for messages that are relevant


@@ -726,6 +778,13 @@ fields.
 .Pp
 Message levels have the following meanings:
 .Bl -tag -width "warning"
 .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
 .It Cm unsupp
 An input file uses unsupported low-level
 .Xr roff 7


@@ -774,8 +833,7 @@ Messages of the
 .Cm error ,
 and
 .Cm unsupp
 .Cm error ,
 and
 .Cm unsupp

-levels except those about non-existent or unreadable input files
-are hidden unless their level, or a lower level, is requested using a
+levels are hidden unless their level, or a lower level, is requested using a

 .Fl W
 option or
 .Fl T Cm lint
 .Fl W
 option or
 .Fl T Cm lint


@@ -863,6 +921,16 @@ Consider using the conventional
 date format
 .Dq "Month dd, yyyy"
 instead.
 date format
 .Dq "Month dd, yyyy"
 instead.

+.It Sy "normalizing date format to" : No ...
+.Pq mdoc , man
+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
 .It Sy "lower case character in document title"
 .Pq mdoc , man
 The title is still used as given in the


@@ -1606,6 +1674,12 @@ or
 .Cm off .
 The invalid argument is moved out of the macro, which leaves the macro
 empty, causing it to toggle the spacing mode.
 .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
 .It Sy "unknown font, skipping request"
 .Pq man , tbl
 A


@@ -1632,9 +1706,12 @@ 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
 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.
 .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:
 .It Sy "tab in filled text"
 .Pq mdoc , man
 The meaning of tab characters is only well-defined in non-fill mode:


@@ -1651,7 +1728,8 @@ 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
 .It Sy "invalid escape sequence"
 .Pq roff
 An escape sequence has an invalid opening argument delimiter, lacks the

-closing argument delimiter, or the argument has too few characters.
+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
 If the argument is incomplete,
 .Ic \e*
 and


@@ -1664,6 +1742,12 @@ and
 .Ic \ew
 to the length of the incomplete argument.
 All other invalid escape sequences are ignored.
 .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,
 .It Sy "undefined string, using \(dq\(dq"
 .Pq roff
 If a string is used without being defined before,


@@ -1807,6 +1891,13 @@ or
 macro.
 It may be mistyped or unsupported.
 The request or macro is discarded including its arguments.
 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
 .It Sy "skipping insecure request"
 .Pq roff
 An input file attempted to run a shell command


@@ -1916,6 +2007,14 @@ 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.
 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 "NOT IMPLEMENTED: Bd -file"
 .Pq mdoc
 For security reasons, the
 .It Sy "NOT IMPLEMENTED: Bd -file"
 .Pq mdoc
 For security reasons, the


@@ -1944,6 +2043,13 @@ macro fails to specify the list type.
 The argument of a
 .Ic \&ce
 request is not a number.
 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 "missing manual name, using \(dq\(dq"
 .Pq mdoc
 The first call to
 .It Sy "missing manual name, using \(dq\(dq"
 .Pq mdoc
 The first call to


@@ -1978,6 +2084,13 @@ or
 .Ic \&gsize
 statement has a non-numeric or negative argument or no argument at all.
 The invalid request or statement is ignored.
 .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,
 .It Sy "NOT IMPLEMENTED: .so with absolute path or \(dq..\(dq"
 .Pq roff
 For security reasons,


@@ -2100,6 +2213,13 @@ implementations but not by
 .Nm
 was found in an input file.
 It is replaced by a question mark.
 .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
 .It Sy "unsupported roff request"
 .Pq roff
 An input file contains a


@@ -2128,6 +2248,43 @@ macro or of an undefined macro.
 The macro is ignored, and its arguments are handled
 as if they were a text line.
 .El
 The macro is ignored, and its arguments are handled
 as if they were a text line.
 .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.
+.El

 .Sh SEE ALSO
 .Xr apropos 1 ,
 .Xr man 1 ,
 .Sh SEE ALSO
 .Xr apropos 1 ,
 .Xr man 1 ,