===================================================================
RCS file: /cvs/mandoc/mandoc.1,v
retrieving revision 1.253
retrieving revision 1.264
diff -u -p -r1.253 -r1.264
--- mandoc/mandoc.1	2021/08/14 13:53:08	1.253
+++ mandoc/mandoc.1	2023/04/28 18:55:09	1.264
@@ -1,6 +1,6 @@
-.\" $OpenBSD: mandoc.1,v 1.253 2021/08/14 13:53:08 schwarze Exp $
+.\" $Id: mandoc.1,v 1.264 2023/04/28 18:55:09 schwarze Exp $
 .\"
-.\" Copyright (c) 2012, 2014-2021 Ingo Schwarze <schwarze@openbsd.org>
+.\" Copyright (c) 2012, 2014-2022 Ingo Schwarze <schwarze@openbsd.org>
 .\" Copyright (c) 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 .\"
 .\" Permission to use, copy, modify, and distribute this software for any
@@ -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: August 14 2021 $
+.Dd $Mdocdate: April 28 2023 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -342,7 +342,6 @@ and may exceed the output width.
 Output produced by
 .Fl T Cm html
 conforms to HTML5 using optional self-closing tags.
-Default styles use only CSS1.
 Equations rendered from
 .Xr eqn 7
 blocks use MathML.
@@ -487,10 +486,10 @@ Use
 to translate
 .Xr mdoc 7
 input to the markdown format conforming to
-.Lk http://daringfireball.net/projects/markdown/syntax.text\
+.Lk https://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.
@@ -735,7 +734,7 @@ 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 /usr/share/misc/mandoc.css
@@ -766,7 +765,7 @@ Messages displayed by
 follow this format:
 .Bd -ragged -offset indent
 .Nm :
-.Ar file : Ns Ar line : Ns Ar column : level : message : macro arguments
+.Ar file : Ns Ar line : Ns Ar column : level : message : macro argument ...
 .Pq Ar os
 .Ed
 .Pp
@@ -786,9 +785,7 @@ and
 strings are explained below.
 The name of the
 .Ar macro
-triggering the message and its
-.Ar arguments
-are omitted where meaningless.
+triggering the message and its arguments are omitted where meaningless.
 The
 .Ar os
 operating system specifier is omitted for messages that are relevant
@@ -835,7 +832,7 @@ 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
@@ -1474,10 +1471,8 @@ A
 .Ic \&Bl ,
 .Ic \&D1 ,
 .Ic \&Dl ,
-.Ic \&MT ,
-.Ic \&RS ,
 or
-.Ic \&UR
+.Ic \&RS
 block contains nothing in its body and will produce no output.
 .It Sy "empty argument, using 0n"
 .Pq mdoc
@@ -1754,6 +1749,15 @@ 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
 A
@@ -1788,23 +1792,10 @@ 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
-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
-.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 invalid escape sequences are ignored.
+The argument of an escape sequence is of an invalid form.
+Invalid escape sequences are ignored.
 .It Sy "undefined escape, printing literally"
 .Pq roff
 In an escape sequence, the first character
@@ -2082,6 +2073,13 @@ and expands to the empty string.
 .Pq roff
 The argument of the escape sequence \e$ is not a digit;
 the escape sequence expands to the empty string.
+.It Sy "negative argument, using 0"
+.Pq roff
+A
+.Ic \&shift
+request has a negative argument
+or an argument that is negative due to integer overflow.
+Macro argument numbering remains unchanged.
 .It Sy "NOT IMPLEMENTED: Bd -file"
 .Pq mdoc
 For security reasons, the
@@ -2117,6 +2115,13 @@ The first argument of a
 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
@@ -2261,6 +2266,60 @@ or
 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]
+or
+.Qq \e[~]
+instead of
+.Qq \ee
+or
+.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 characters 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