===================================================================
RCS file: /cvs/mandoc/mandoc_html.3,v
retrieving revision 1.3
retrieving revision 1.8
diff -u -p -r1.3 -r1.8
--- mandoc/mandoc_html.3	2017/01/17 15:32:44	1.3
+++ mandoc/mandoc_html.3	2017/05/12 17:58:21	1.8
@@ -1,4 +1,4 @@
-.\"	$Id: mandoc_html.3,v 1.3 2017/01/17 15:32:44 schwarze Exp $
+.\"	$Id: mandoc_html.3,v 1.8 2017/05/12 17:58:21 schwarze Exp $
 .\"
 .\" Copyright (c) 2014, 2017 Ingo Schwarze <schwarze@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" 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 17 2017 $
+.Dd $Mdocdate: May 12 2017 $
 .Dt MANDOC_HTML 3
 .Os
 .Sh NAME
@@ -48,6 +48,14 @@
 .Fa "struct html *h"
 .Fa "const char *word"
 .Fc
+.Ft char *
+.Fo html_make_id
+.Fa "const struct roff_node *n"
+.Fc
+.Ft int
+.Fo html_strlen
+.Fa "const char *cp"
+.Fc
 .Sh DESCRIPTION
 The mandoc HTML formatter is not a formal library.
 However, as it is compiled into more than one program, in particular
@@ -137,11 +145,19 @@ Most attributes require one
 .Va char *
 argument which becomes the value of the attribute.
 The arguments have to be given in the same order as the attribute letters.
+If an argument is
+.Dv NULL ,
+the respective attribute is not written.
 .Bl -tag -width 1n -offset indent
 .It Cm c
 Print a
 .Cm class
 attribute.
+This attribute letter can optionally be followed by the modifier letter
+.Cm T .
+In that case, a
+.Cm title
+attribute with the same value is also printed.
 .It Cm h
 Print a
 .Cm href
@@ -175,18 +191,20 @@ Print an arbitrary attribute.
 This format letter requires two
 .Vt char *
 arguments, the attribute name and the value.
+The name must not be
+.Dv NULL .
 .It Cm s
 Print a
 .Cm style
 attribute.
 If present, it must be the last format letter.
 In contrast to the other format letters, this one does not yet
-print the value and does not require an argument.
+print the value and does not take an argument.
 Instead, the rest of the format string consists of pairs of
 argument type letters and style name letters.
 .El
 .Pp
-Argument type letters each require on argument as follows:
+Argument type letters each require one argument as follows:
 .Bl -tag -width 1n -offset indent
 .It Cm h
 Requires one
@@ -212,6 +230,21 @@ Requires one
 argument, interpreted as an
 .Xr mdoc 7 Ns -style
 width specifier.
+If the argument is
+.Dv NULL ,
+nothing is printed for this pair.
+.Pp
+The
+.Cm w
+argument type letter can optionally be followed by one or two
+modifier letters.
+The modifier
+.Cm +
+increases the width by 10% to make even bold text fit
+and adds two units for padding between columns.
+The modifier
+.Cm \-
+makes the width negative by multiplying it with \-1.
 .El
 .Pp
 Style name letters decide what to do with the preceding argument:
@@ -251,6 +284,8 @@ requires two
 .Vt char *
 arguments.
 The first is the style name, the second its value.
+The style name must not be
+.Dv NULL .
 .El
 .Pp
 .Fn print_otag
@@ -287,8 +322,27 @@ and
 .Fn print_tagq
 functions.
 .Pp
+The function
+.Fn html_make_id
+takes a node containing one or more text children
+and returns a newly allocated string containing the concatenation
+of the child strings, with blanks replaced by underscores.
+If the node
+.Fa n
+contains any non-text child node,
+.Fn html_make_id
+returns
+.Dv NULL
+instead.
+The caller is responsible for freeing the returned string.
+.Pp
+The function
+.Fn html_strlen
+counts the number of characters in
+.Fa cp .
+It is used as a crude estimate of the width needed to display a string.
+.Pp
 The functions
-.Fn html_strlen ,
 .Fn print_eqn ,
 .Fn print_tbl ,
 and
@@ -336,5 +390,6 @@ implementation of common mandoc utility functions
 .An -nosplit
 The mandoc HTML formatter was written by
 .An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .
-This manual was written by
-.An Ingo Schwarze Aq Mt schwarze@openbsd.org .
+It is maintained by
+.An Ingo Schwarze Aq Mt schwarze@openbsd.org ,
+who also wrote this manual.