===================================================================
RCS file: /cvs/mandoc/mandoc.1,v
retrieving revision 1.239
retrieving revision 1.240
diff -u -p -r1.239 -r1.240
--- mandoc/mandoc.1	2019/05/26 01:28:09	1.239
+++ mandoc/mandoc.1	2019/07/10 19:39:01	1.240
@@ -1,7 +1,7 @@
-.\"	$Id: mandoc.1,v 1.239 2019/05/26 01:28:09 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) 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
@@ -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: May 26 2019 $
+.Dd $Mdocdate: July 10 2019 $
 .Dt MANDOC 1
 .Os
 .Sh NAME
@@ -698,7 +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.
-Such errors cause
+Such errors may cause
 .Nm
 to exit at once, possibly in the middle of parsing or formatting a file.
 .El
@@ -778,6 +778,13 @@ 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
@@ -826,8 +833,7 @@ Messages of the
 .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
@@ -2241,6 +2247,43 @@ or
 macro or of an undefined macro.
 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 ,