===================================================================
RCS file: /cvs/mandoc/mandoc.1,v
retrieving revision 1.138
retrieving revision 1.177
diff -u -p -r1.138 -r1.177
--- mandoc/mandoc.1	2015/01/26 18:42:30	1.138
+++ mandoc/mandoc.1	2017/03/06 17:26:04	1.177
@@ -1,7 +1,7 @@
-.\"	$Id: mandoc.1,v 1.138 2015/01/26 18:42:30 schwarze Exp $
+.\"	$Id: mandoc.1,v 1.177 2017/03/06 17:26:04 schwarze Exp $
 .\"
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
-.\" Copyright (c) 2012, 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
+.\" Copyright (c) 2012, 2014-2017 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
@@ -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.
 .\"
-.Dd $Mdocdate: January 26 2015 $
+.Dd $Mdocdate: March 6 2017 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -23,15 +23,13 @@
 .Nd format and display UNIX manuals
 .Sh SYNOPSIS
 .Nm mandoc
-.Op Fl acfhklV
-.Sm off
-.Op Fl I Cm os Li = Ar name
-.Sm on
-.Op Fl K Ns Ar encoding
+.Op Fl acfhkl
+.Op Fl I Cm os Ns = Ns Ar name
+.Op Fl K Ar encoding
 .Op Fl m Ns Ar format
-.Op Fl O Ns Ar option
-.Op Fl T Ns Ar output
-.Op Fl W Ns Ar level
+.Op Fl O Ar option
+.Op Fl T Ar output
+.Op Fl W Ar level
 .Op Ar
 .Sh DESCRIPTION
 The
@@ -49,7 +47,7 @@ or
 text from stdin, implying
 .Fl m Ns Cm andoc ,
 and produces
-.Fl T Ns Cm locale
+.Fl T Cm locale
 output.
 .Pp
 The options are as follows:
@@ -77,9 +75,11 @@ This overrides any earlier
 and
 .Fl l
 options.
-.Sm off
-.It Fl I Cm os Li = Ar name
-.Sm on
+.It Fl h
+Display only the SYNOPSIS lines.
+Implies
+.Fl c .
+.It Fl I Cm os Ns = Ns Ar name
 Override the default operating system
 .Ar name
 for the
@@ -89,11 +89,7 @@ and for the
 .Xr man 7
 .Sq \&TH
 macro.
-.It Fl h
-Display only the SYNOPSIS lines.
-Implies
-.Fl c .
-.It Fl K Ns Ar encoding
+.It Fl K Ar encoding
 Specify the input encoding.
 The supported
 .Ar encoding
@@ -102,21 +98,29 @@ arguments are
 .Cm iso-8859-1 ,
 and
 .Cm utf-8 .
-If not specified, autodetection uses the first match:
-.Bl -tag -width iso-8859-1
-.It Cm utf-8
-if the first three bytes of the input file
-are the UTF-8 byte order mark (BOM, 0xefbbbf)
-.It Ar encoding
-if the first or second line of the input file matches the
+If not specified, autodetection uses the first match in the following
+list:
+.Bl -enum
+.It
+If the first three bytes of the input file are the UTF-8 byte order
+mark (BOM, 0xefbbbf), input is interpreted as
+.Cm utf-8 .
+.It
+If the first or second line of the input file matches the
 .Sy emacs
 mode line format
 .Pp
 .D1 .\e" -*- Oo ...; Oc coding: Ar encoding ; No -*-
-.It Cm utf-8
-if the first non-ASCII byte in the file introduces a valid UTF-8 sequence
-.It Cm iso-8859-1
-otherwise
+.Pp
+then input is interpreted according to
+.Ar encoding .
+.It
+If the first non-ASCII byte in the file introduces a valid UTF-8
+sequence, input is interpreted as
+.Cm utf-8 .
+.It
+Otherwise, input is interpreted as
+.Cm iso-8859-1 .
 .El
 .It Fl k
 A synonym for
@@ -141,18 +145,16 @@ See
 for available formats.
 Defaults to
 .Fl m Ns Cm andoc .
-.It Fl O Ns Ar option
+.It Fl O Ar option
 Comma-separated output options.
-.It Fl T Ns Ar output
+.It Fl T Ar output
 Output format.
 See
 .Sx Output Formats
 for available formats.
 Defaults to
-.Fl T Ns Cm locale .
-.It Fl V
-Print version and exit.
-.It Fl W Ns Ar level
+.Fl T Cm locale .
+.It Fl W Ar level
 Specify the minimum message
 .Ar level
 to be reported on the standard error output and to affect the exit status.
@@ -176,7 +178,7 @@ and
 for details.
 .Pp
 The special option
-.Fl W Ns Cm stop
+.Fl W Cm stop
 tells
 .Nm
 to exit after parsing a file that causes warnings or errors of at least
@@ -187,7 +189,7 @@ If both a
 and
 .Cm stop
 are requested, they can be joined with a comma, for example
-.Fl W Ns Cm error , Ns Cm stop .
+.Fl W Cm error , Ns Cm stop .
 .It Ar file
 Read input from zero or more files.
 If unspecified, reads from stdin.
@@ -256,54 +258,62 @@ The
 utility accepts the following
 .Fl T
 arguments, which correspond to output modes:
-.Bl -tag -width "-Tlocale"
-.It Fl T Ns Cm ascii
+.Bl -tag -width "-T markdown"
+.It Fl T Cm ascii
 Produce 7-bit ASCII output.
 See
 .Sx ASCII Output .
-.It Fl T Ns Cm html
+.It Fl T Cm html
 Produce HTML5, CSS1, and MathML output.
 See
 .Sx HTML Output .
-.It Fl T Ns Cm lint
+.It Fl T Cm lint
 Parse only: produce no output.
 Implies
-.Fl W Ns Cm warning .
-.It Fl T Ns Cm locale
+.Fl W Cm warning .
+.It Fl T Cm locale
 Encode output using the current locale.
 This is the default.
 See
 .Sx Locale Output .
-.It Fl T Ns Cm man
+.It Fl T Cm man
 Produce
 .Xr man 7
 format output.
 See
 .Sx Man Output .
-.It Fl T Ns Cm pdf
+.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 Ns Cm ps
+.It Fl T Cm ps
 Produce PostScript output.
 See
 .Sx PostScript Output .
-.It Fl T Ns Cm tree
+.It Fl T Cm tree
 Produce an indented parse tree.
-.It Fl T Ns Cm utf8
+See
+.Sx Syntax tree output .
+.It Fl T Cm utf8
 Encode output in the UTF\-8 multi-byte format.
 See
 .Sx UTF\-8 Output .
-.It Fl T Ns Cm xhtml
+.It Fl T Cm xhtml
 This is a synonym for
-.Fl T Ns Cm html .
+.Fl T Cm html .
 .El
 .Pp
 If multiple input files are specified, these will be processed by the
 corresponding filter in-order.
 .Ss ASCII Output
 Output produced by
-.Fl T Ns Cm ascii
+.Fl T Cm ascii
 is rendered in standard 7-bit ASCII documented in
 .Xr ascii 7 .
 .Pp
@@ -321,9 +331,6 @@ Emboldened characters are rendered as
 The special characters documented in
 .Xr mandoc_char 7
 are rendered best-effort in an ASCII equivalent.
-If no equivalent is found,
-.Sq \&?
-is used instead.
 .Pp
 Output width is limited to 78 visible columns unless literal input lines
 exceed this limit.
@@ -344,11 +351,11 @@ for example overfull lines or ugly line breaks.
 .It Cm width Ns = Ns Ar width
 The output width is set to
 .Ar width ,
-which will normalise to \(>=60.
+which will normalise to \(>=58.
 .El
 .Ss HTML Output
 Output produced by
-.Fl T Ns Cm html
+.Fl T Cm html
 conforms to HTML5 using optional self-closing tags.
 Default styles use only CSS1.
 Equations rendered from
@@ -356,11 +363,11 @@ Equations rendered from
 blocks use MathML.
 .Pp
 The
-.Pa example.style.css
+.Pa mandoc.css
 file documents style-sheet classes available for customising output.
 If a style-sheet is not specified with
-.Fl O Ns Ar style ,
-.Fl T Ns Cm html
+.Fl O Cm style ,
+.Fl T Cm html
 defaults to simple output (via an embedded style-sheet)
 readable in any graphical or text-based web
 browser.
@@ -416,13 +423,13 @@ relative URI.
 .El
 .Ss Locale Output
 Locale-depending output encoding is triggered with
-.Fl T Ns 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 Ns Cm ascii .
+.Fl T Cm ascii .
 See
 .Sx ASCII Output
 for font style specification and available command-line arguments.
@@ -450,9 +457,33 @@ The parser is also run, and as usual, the
 level controls which
 .Sx DIAGNOSTICS
 are displayed before copying the input to the output.
+.Ss Markdown Output
+Translate
+.Xr mdoc 7
+input to the
+.Sy markdown
+format conforming to
+.Lk http://daringfireball.net/projects/markdown/syntax.text\
+ "John Gruber's 2004 specification" .
+.Pp
+Markdown is a very weak markup language, so all semantic markup is
+lost, and even part of the presentational markup may be lost.
+Do not use this as an intermediate step in converting to HTML;
+instead, use
+.Fl T Cm html
+directly.
+.Pp
+The
+.Xr man 7 ,
+.Xr tbl 7 ,
+and
+.Xr eqn 7
+input languages are not supported by
+.Fl T Cm markdown
+output mode.
 .Ss PDF Output
 PDF-1.1 output may be generated by
-.Fl T Ns Cm pdf .
+.Fl T Cm pdf .
 See
 .Sx PostScript Output
 for
@@ -462,7 +493,7 @@ arguments and defaults.
 PostScript
 .Qq Adobe-3.0
 Level-2 pages may be generated by
-.Fl T Ns Cm ps .
+.Fl T Cm ps .
 Output pages default to letter sized and are rendered in the Times font
 family, 11-point.
 Margins are calculated as 1/9 the page length and width.
@@ -494,11 +525,77 @@ is used.
 .El
 .Ss UTF\-8 Output
 Use
-.Fl T Ns Cm utf8
+.Fl T Cm utf8
 to force a UTF\-8 locale.
 See
 .Sx Locale Output
 for details and options.
+.Ss Syntax tree output
+Use
+.Fl T Cm tree
+to show a human readable representation of the syntax tree.
+It is useful for debugging the source code of manual pages.
+The exact format is subject to change, so don't write parsers for it.
+.Pp
+The first paragraph shows meta data found in the
+.Xr mdoc 7
+prologue, on the
+.Xr man 7
+.Ic \&TH
+line, or the fallbacks used.
+.Pp
+In the tree dump, each output line shows one syntax tree node.
+Child nodes are indented with respect to their parent node.
+The columns are:
+.Pp
+.Bl -enum -compact
+.It
+For macro nodes, the macro name; for text and
+.Xr tbl 7
+nodes, the content.
+There is a special format for
+.Xr eqn 7
+nodes.
+.It
+Node type (text, elem, block, head, body, body-end, tail, tbl, eqn).
+.It
+Flags:
+.Bl -dash -compact
+.It
+An opening parenthesis if the node is an opening delimiter.
+.It
+An asterisk if the node starts a new input line.
+.It
+The input line number (starting at one).
+.It
+A colon.
+.It
+The input column number (starting at one).
+.It
+A closing parenthesis if the node is a closing delimiter.
+.It
+A full stop if the node ends a sentence.
+.It
+BROKEN if the node is a block broken by another block.
+.It
+NOSRC if the node is not in the input file,
+but automatically generated from macros.
+.It
+NOPRT if the node is not supposed to generate output
+for any output format.
+.El
+.El
+.Pp
+The following
+.Fl O
+argument is accepted:
+.Bl -tag -width Ds
+.It Cm noval
+Skip validation and show the unvalidated syntax tree.
+This can help to find out whether a given behaviour is caused by
+the parser or by the validator.
+Meta data is not available in this case.
+.El
 .Sh ENVIRONMENT
 .Bl -tag -width MANPAGER
 .It Ev MANPAGER
@@ -511,7 +608,8 @@ Specifies the pagination program to use when
 .Ev MANPAGER
 is not defined.
 If neither PAGER nor MANPAGER is defined,
-.Pa /usr/bin/more Fl s
+.Xr more 1
+.Fl s
 will be used.
 .El
 .Sh EXIT STATUS
@@ -530,21 +628,21 @@ they were lower than the requested
 .Ar level .
 .It 2
 At least one warning occurred, but no error, and
-.Fl W Ns Cm warning
+.Fl W Cm warning
 was specified.
 .It 3
 At least one parsing error occurred,
 but no unsupported feature was encountered, and
-.Fl W Ns Cm error
+.Fl W Cm error
 or
-.Fl W Ns Cm warning
+.Fl W Cm warning
 was specified.
 .It 4
 At least one unsupported feature was encountered, and
-.Fl W Ns Cm unsupp ,
-.Fl W Ns Cm error
+.Fl W Cm unsupp ,
+.Fl W Cm error
 or
-.Fl W Ns Cm warning
+.Fl W Cm warning
 was specified.
 .It 5
 Invalid command line arguments were specified.
@@ -558,28 +656,28 @@ to exit at once, possibly in the middle of parsing or 
 .El
 .Pp
 Note that selecting
-.Fl T Ns Cm lint
+.Fl T Cm lint
 output mode implies
-.Fl W Ns Cm warning .
+.Fl W Cm warning .
 .Sh EXAMPLES
 To page manuals to the terminal:
 .Pp
-.Dl $ mandoc \-Wall,stop mandoc.1 2\*(Gt&1 | less
+.Dl $ mandoc \-W all,stop mandoc.1 2\*(Gt&1 | less
 .Dl $ mandoc mandoc.1 mdoc.3 mdoc.7 | less
 .Pp
 To produce HTML manuals with
-.Ar style.css
+.Pa mandoc.css
 as the style-sheet:
 .Pp
-.Dl $ mandoc \-Thtml -Ostyle=style.css mdoc.7 \*(Gt mdoc.7.html
+.Dl $ mandoc \-T html -O style=mandoc.css mdoc.7 \*(Gt mdoc.7.html
 .Pp
 To check over a large set of manuals:
 .Pp
-.Dl $ mandoc \-Tlint `find /usr/src -name \e*\e.[1-9]`
+.Dl $ mandoc \-T lint \(gafind /usr/src -name \e*\e.[1-9]\(ga
 .Pp
 To produce a series of PostScript manuals for A4 paper:
 .Pp
-.Dl $ mandoc \-Tps \-Opaper=a4 mdoc.7 man.7 \*(Gt manuals.ps
+.Dl $ mandoc \-T ps \-O paper=a4 mdoc.7 man.7 \*(Gt manuals.ps
 .Pp
 Convert a modern
 .Xr mdoc 7
@@ -589,7 +687,7 @@ format, for use on systems lacking an
 .Xr mdoc 7
 parser:
 .Pp
-.Dl $ mandoc \-Tman foo.mdoc \*(Gt foo.man
+.Dl $ mandoc \-T man foo.mdoc \*(Gt foo.man
 .Sh DIAGNOSTICS
 Messages displayed by
 .Nm
@@ -656,7 +754,7 @@ levels except those about non-existent or unreadable i
 are hidden unless their level, or a lower level, is requested using a
 .Fl W
 option or
-.Fl T Ns Cm lint
+.Fl T Cm lint
 output mode.
 .Ss Warnings related to the document prologue
 .Bl -ohang
@@ -732,9 +830,9 @@ macro occurs after some non-prologue macro, but still 
 .Pq mdoc
 The
 .Ic \&Dt
-macro can only occur before the first non-prologue macro
-because traditional formatters write the page header
-before parsing the document body.
+macro appears after the first non-prologue macro.
+Traditional formatters cannot handle this because
+they write the page header before parsing the document body.
 Even though this technical restriction does not apply to
 .Nm ,
 traditional semantics is preserved.
@@ -776,17 +874,48 @@ This may confuse
 .Xr makewhatis 8
 and
 .Xr apropos 1 .
-.It Sy "bad NAME section contents"
+.It Sy "NAME section without Nm before Nd"
 .Pq mdoc
-The last node in the NAME section is not an
+The NAME section does not contain any
+.Ic \&Nm
+child macro before the first
 .Ic \&Nd
-macro, or any preceding macro is not
-.Ic \&Nm ,
-or the NAME section is completely empty.
-This may confuse
-.Xr makewhatis 8
+macro.
+.It Sy "NAME section without description"
+.Pq mdoc
+The NAME section lacks the mandatory
+.Ic \&Nd
+child macro.
+.It Sy "description not at the end of NAME"
+.Pq mdoc
+The NAME section does contain an
+.Ic \&Nd
+child macro, but other content follows it.
+.It Sy "bad NAME section content"
+.Pq mdoc
+The NAME section contains plain text or macros other than
+.Ic \&Nm
 and
-.Xr apropos 1 .
+.Ic \&Nd .
+.It Sy "missing comma before name"
+.Pq mdoc
+The NAME section contains an
+.Ic \&Nm
+macro that is neither the first one nor preceded by a comma.
+.It Sy "missing description line, using \(dq\(dq"
+.Pq mdoc
+The
+.Ic \&Nd
+macro lacks the required argument.
+The title line of the manual will end after the dash.
+.It Sy "description line outside NAME section"
+.Pq mdoc
+An
+.Ic \&Nd
+macro appears outside the NAME section.
+The arguments are printed anyway and the following text is used for
+.Xr apropos 1 ,
+but none of that behaviour is portable.
 .It Sy "sections out of conventional order"
 .Pq mdoc
 A standard section occurs after another section it usually precedes.
@@ -806,7 +935,7 @@ In the SEE ALSO section, an
 macro with a lower section number follows one with a higher number,
 or two
 .Ic \&Xr
-macros refering to the same section are out of alphabetical order.
+macros referring to the same section are out of alphabetical order.
 .It Sy "unusual Xr punctuation"
 .Pq mdoc
 In the SEE ALSO section, punctuation between two
@@ -833,7 +962,7 @@ manual for replacements.
 .Pq 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 line;
+If the intention is to call it, move it to its own input line;
 otherwise, escape it by prepending
 .Sq \e& .
 .It Sy "skipping paragraph macro"
@@ -926,13 +1055,6 @@ list block contains text or macros before the first
 .Ic \&It
 macro.
 The offending children are moved before the beginning of the list.
-.It Sy ".Vt block has child macro"
-.Pq mdoc
-The
-.Ic \&Vt
-macro supports plain text arguments only.
-Formatting may be ugly and semantic searching
-for the affected content might not work.
 .It Sy "fill mode already enabled, skipping"
 .Pq man
 A
@@ -992,6 +1114,18 @@ clause.
 .It Sy "skipping empty macro"
 .Pq mdoc
 The indicated macro has no arguments and hence no effect.
+.It Sy "empty block"
+.Pq mdoc , man
+A
+.Ic \&Bd ,
+.Ic \&Bk ,
+.Ic \&Bl ,
+.Ic \&D1 ,
+.Ic \&Dl ,
+.Ic \&RS ,
+or
+.Ic \&UR
+block contains nothing in its body and will produce no output.
 .It Sy "empty argument, using 0n"
 .Pq mdoc
 The required width is missing after
@@ -1001,12 +1135,6 @@ or
 .Fl offset
 or
 .Fl width.
-.It Sy "argument count wrong"
-.Pq mdoc , man
-The indicated macro has too few or too many arguments.
-The syntax tree will contain the wrong number of arguments as given.
-Formatting behaviour depends on the specific macro in question.
-Note that the same message may also occur as an ERROR, see below.
 .It Sy "missing display type, using -ragged"
 .Pq mdoc
 The
@@ -1038,6 +1166,12 @@ The
 macro is called without an argument before
 .Ic \&Nm
 has first been called with an argument.
+.It Sy "missing function name, using \(dq\(dq"
+.Pq mdoc
+The
+.Ic \&Fo
+macro is called without an argument.
+No function name is printed.
 .It Sy "empty head in list item"
 .Pq mdoc
 In a
@@ -1065,21 +1199,18 @@ list, an
 .Ic \&It
 block is empty.
 An empty list item is shown.
-.It Sy "missing font type"
+.It Sy "missing font type, using \efR"
 .Pq mdoc
 A
 .Ic \&Bf
 macro has no argument.
-It switches to the default font,
-.Cm \efR .
-.It Sy "unknown font type"
+It switches to the default font.
+.It Sy "unknown font type, using \efR"
 .Pq mdoc
 The
 .Ic \&Bf
 argument is invalid.
-The default font
-.Cm \efR
-is used instead.
+The default font is used instead.
 .It Sy "nothing follows prefix"
 .Pq mdoc
 A
@@ -1088,6 +1219,21 @@ macro has no argument, or only one argument and no mac
 on the same input line.
 This defeats its purpose; in particular, spacing is not suppressed
 before the text or macros following on the next input line.
+.It Sy "empty reference block"
+.Pq mdoc
+An
+.Ic \&Rs
+macro is immediately followed by an
+.Ic \&Re
+macro on the next input line.
+Such an empty block does not produce any output.
+.It Sy "missing section argument"
+.Pq mdoc
+An
+.Ic \&Xr
+macro lacks its second, section number argument.
+The first argument, i.e. the name, is printed, but without subsequent
+parentheses.
 .It Sy "missing -std argument, adding it"
 .Pq mdoc
 An
@@ -1102,6 +1248,18 @@ The
 utility assumes
 .Fl std
 even when it is not specified, but other implementations may not.
+.It Sy "missing option string, using \(dq\(dq"
+.Pq man
+The
+.Ic \&OP
+macro is invoked without any argument.
+An empty pair of square brackets is shown.
+.It Sy "missing resource identifier, using \(dq\(dq"
+.Pq man
+The
+.Ic \&UR
+macro is invoked without any argument.
+An empty pair of angle brackets is shown.
 .It Sy "missing eqn box, using \(dq\(dq"
 .Pq eqn
 A diacritic mark or a binary operator is found,
@@ -1166,6 +1324,15 @@ list has a
 .Fl width
 argument.
 That has no effect.
+.It Sy "wrong number of cells"
+In a line of a
+.Ic \&Bl Fl column
+list, the number of tabs or
+.Ic \&Ta
+macros is less than the number expected from the list header line
+or exceeds the expected number by more than one.
+Missing cells remain empty, and all cells exceeding the number of
+columns are joined into one single cell.
 .It Sy "unknown AT&T UNIX version"
 .Pq mdoc
 An
@@ -1217,6 +1384,12 @@ request or a
 layout modifier has an unknown
 .Ar font
 argument.
+.It Sy "odd number of characters in request"
+.Pq roff
+A
+.Ic \&tr
+request contains an odd number of characters.
+The last character is mapped to the blank character.
 .El
 .Ss "Warnings related to plain text"
 .Bl -ohang
@@ -1243,6 +1416,10 @@ it is hard to predict which tab stop position the tab 
 Whitespace at the end of input lines is almost never semantically
 significant \(em but in the odd case where it might be, it is
 extremely confusing when reviewing and maintaining documents.
+.It Sy "new sentence, new line"
+.Pq mdoc
+A new sentence starts in the middle of a text line.
+Start it on a new input line to help formatters produce correct spacing.
 .It Sy "bad comment style"
 .Pq roff
 Comment lines start with a dot, a backslash, and a double-quote character.
@@ -1291,13 +1468,6 @@ Data provided for this cell is ignored, and nothing is
 A table layout specification contains more than two consecutive vertical bars.
 A double bar is printed, all additional bars are discarded.
 .El
-.Ss "Errors related to equations"
-.Bl -inset -compact
-.It "unexpected equation scope closure"
-.It "equation scope open on exit"
-.It "overlapping equation scopes"
-.It "unexpected end of equation"
-.El
 .Ss "Errors related to tables"
 .Bl -ohang
 .It Sy "non-alphabetic character in tbl options"
@@ -1336,14 +1506,31 @@ 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 "tbl without any data cells"
+.Pq tbl
+A table does not contain any data cells.
+It will probably produce no output.
+.It Sy "ignoring data in spanned tbl cell"
+.Pq tbl
+A table cell is marked as a horizontal span
+.Pq Sq Cm s
+or vertical span
+.Pq Sq Cm ^
+in the table layout, but it contains data.
+The data is ignored.
+.It Sy "ignoring extra tbl data cells"
+.Pq tbl
+A data line contains more cells than the corresponding layout line.
+The data in the extra cells is ignored.
+.It Sy "data block open at end of tbl"
+.Pq tbl
+A data block is opened with
+.Cm T{ ,
+but never closed with a matching
+.Cm T} .
+The remaining data lines of the table are all put into one cell,
+and any remaining cells stay empty.
 .El
-.Pp
-.Bl -inset -compact
-.It Sy "no table data cells specified"
-.It Sy "ignore data in cell"
-.It Sy "data block still open"
-.It Sy "ignoring extra data cells"
-.El
 .Ss "Errors related to roff, mdoc, and man code"
 .Bl -ohang
 .It Sy "input stack limit exceeded, infinite loop?"
@@ -1443,7 +1630,7 @@ macros as well as tables require explicit closing by d
 A block that doesn't support bad nesting
 ends before all of its children are properly closed.
 The open child nodes are closed implicitly.
-.It Sy "scope open on exit"
+.It Sy "appending missing end of block"
 .Pq mdoc , man , eqn , tbl , roff
 At the end of the document, an explicit
 .Xr mdoc 7
@@ -1493,12 +1680,6 @@ 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 "argument count wrong"
-.Pq mdoc , man , roff
-The indicated request or macro has too few or too many arguments.
-The syntax tree will contain the wrong number of arguments as given.
-Formatting behaviour depends on the specific request or macro in question.
-Note that the same message may also occur as a WARNING, see above.
 .It Sy "NOT IMPLEMENTED: Bd -file"
 .Pq mdoc
 For security reasons, the
@@ -1510,6 +1691,13 @@ By requesting the inclusion of a sensitive file, a mal
 might otherwise trick a privileged user into inadvertently displaying
 the file on the screen, revealing the file content to bystanders.
 The argument is ignored including the file name following it.
+.It Sy "skipping display without arguments"
+.Pq mdoc
+A
+.Ic \&Bd
+block macro does not have any arguments.
+The block is discarded, and the block content is displayed in
+whatever mode was active before the block.
 .It Sy "missing list type, using -item"
 .Pq mdoc
 A
@@ -1518,8 +1706,8 @@ macro fails to specify the list type.
 .It Sy "missing manual name, using \(dq\(dq"
 .Pq mdoc
 The first call to
-.Ic \&Nm
-lacks the required argument.
+.Ic \&Nm ,
+or any call in the NAME section, lacks the required argument.
 .It Sy "uname(3) system call failed, using UNKNOWN"
 .Pq mdoc
 The
@@ -1581,7 +1769,10 @@ An
 .Ic \&Ef ,
 .Ic \&Ek ,
 .Ic \&El ,
+.Ic \&Lp ,
+.Ic \&Pp ,
 .Ic \&Re ,
+.Ic \&Rs ,
 or
 .Ic \&Ud
 macro, an
@@ -1599,19 +1790,54 @@ or
 .Ic \&EN
 macro, or a
 .Xr roff 7
+.Ic \&br ,
+.Ic \&fi ,
+or
+.Ic \&nf
+request or
 .Sq \&..
 block closing request is invoked with at least one argument.
 All arguments are ignored.
 .It Sy "skipping excess arguments"
 .Pq mdoc , man , roff
-The
-.Ic \&Bf
-macro is invoked with more than one argument, the
+A macro or request is invoked with too many arguments:
+.Bl -dash -offset 2n -width 2n -compact
+.It
+.Ic \&Fo ,
+.Ic \&PD ,
+.Ic \&RS ,
+.Ic \&UR ,
+.Ic \&ft ,
+or
+.Ic \&sp
+with more than one argument
+.It
+.Ic \&An
+with another argument after
+.Fl split
+or
+.Fl nosplit
+.It
 .Ic \&RE
-macro is invoked with more than one argument
-or with a non-integer argument, or a request of the
+with more than one argument or with a non-integer argument
+.It
+.Ic \&OP
+or a request of the
 .Ic \&de
-family is invoked with more than two arguments.
+family with more than two arguments
+.It
+.Ic \&Dt
+with more than three arguments
+.It
+.Ic \&TH
+with more than five arguments
+.It
+.Ic \&Bd ,
+.Ic \&Bk ,
+or
+.Ic \&Bl
+with invalid arguments
+.El
 The excess arguments are ignored.
 .El
 .Ss Unsupported features
@@ -1640,136 +1866,53 @@ request supported by GNU troff or Heirloom troff but n
 .Nm ,
 and it is likely that this will cause information loss
 or considerable misformatting.
-.It Sy "unsupported table layout modfier"
+.It Sy "eqn delim option in tbl"
+.Pq eqn , tbl
+The options line of a table defines equation delimiters.
+Any equation source code contained in the table will be printed unformatted.
+.It Sy "unsupported table layout modifier"
 .Pq tbl
 A table layout specification contains an
 .Sq Cm m
 modifier.
 The modifier is discarded.
 .It Sy "ignoring macro in table"
-.It Sy "eqn in tbl"
-.Pq eqn , tbl
-The options line of a table defines equation delimiters.
-Any equation source code contained in the table will be printed unformatted.
-.El
-.Sh COMPATIBILITY
-This section summarises
-.Nm
-compatibility with GNU troff.
-Each input and output format is separately noted.
-.Ss ASCII Compatibility
-.Bl -bullet -compact
-.It
-Unrenderable unicode codepoints specified with
-.Sq \e[uNNNN]
-escapes are printed as
-.Sq \&?
-in mandoc.
-In GNU troff, these raise an error.
-.It
-The
-.Sq \&Bd \-literal
-and
-.Sq \&Bd \-unfilled
-macros of
+.Pq tbl , mdoc , man
+A table contains an invocation of an
 .Xr mdoc 7
-in
-.Fl T Ns Cm ascii
-are synonyms, as are \-filled and \-ragged.
-.It
-In historic GNU troff, the
-.Sq \&Pa
-.Xr mdoc 7
-macro does not underline when scoped under an
-.Sq \&It
-in the FILES section.
-This behaves correctly in
-.Nm .
-.It
-A list or display following the
-.Sq \&Ss
-.Xr mdoc 7
-macro in
-.Fl T Ns Cm ascii
-does not assert a prior vertical break, just as it doesn't with
-.Sq \&Sh .
-.It
-The
-.Sq \&na
+or
 .Xr man 7
-macro in
-.Fl T Ns Cm ascii
-has no effect.
-.It
-Words aren't hyphenated.
+macro or of an undefined macro.
+The macro is ignored, and its arguments are handled
+as if they were a text line.
 .El
-.Ss HTML Compatibility
-.Bl -bullet -compact
-.It
-The
-.Sq \efP
-escape will revert the font to the previous
-.Sq \ef
-escape, not to the last rendered decoration, which is now dictated by
-CSS instead of hard-coded.
-It also will not span past the current scope,
-for the same reason.
-Note that in
-.Sx ASCII Output
-mode, this will work fine.
-.It
-The
-.Xr mdoc 7
-.Sq \&Bl \-hang
-and
-.Sq \&Bl \-tag
-list types render similarly (no break following overreached left-hand
-side) due to the expressive constraints of HTML.
-.It
-The
-.Xr man 7
-.Sq IP
-and
-.Sq TP
-lists render similarly.
-.El
 .Sh SEE ALSO
+.Xr apropos 1 ,
+.Xr man 1 ,
 .Xr eqn 7 ,
 .Xr man 7 ,
 .Xr mandoc_char 7 ,
 .Xr mdoc 7 ,
 .Xr roff 7 ,
 .Xr tbl 7
-.Sh AUTHORS
+.Sh HISTORY
 The
 .Nm
-utility was written by
-.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .
-.Sh CAVEATS
-In
-.Fl T Ns Cm html
+utility first appeared in
+.Ox 4.8 .
+The option
+.Fl I
+appeared in
+.Ox 5.2 ,
 and
-.Fl T Ns Cm xhtml ,
-the maximum size of an element attribute is determined by
-.Dv BUFSIZ ,
-which is usually 1024 bytes.
-Be aware of this when setting long link
-formats such as
-.Fl O Ns Cm style Ns = Ns Ar really/long/link .
-.Pp
-Nesting elements within next-line element scopes of
-.Fl m Ns Cm an ,
-such as
-.Sq br
-within an empty
-.Sq B ,
-will confuse
-.Fl T Ns Cm html
-and
-.Fl T Ns Cm xhtml
-and cause them to forget the formatting of the prior next-line scope.
-.Pp
+.Fl aCcfhKklMSsw
+in
+.Ox 5.7 .
+.Sh AUTHORS
+.An -nosplit
 The
-.Sq \(aq
-control character is an alias for the standard macro control character
-and does not emit a line-break as stipulated in GNU troff.
+.Nm
+utility was written by
+.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
+and is maintained by
+.An Ingo Schwarze Aq Mt schwarze@openbsd.org .