Problems with rowsep & colsep in informaltable

["Christof M. von Ah" <Christof.vonAh@gmx.ch>]

Hi,

I'm about to write a book and want to make the table border as well as the
row and column borders invisible.
This works fine in HTML output but not in PDF output (which I'm much more
interested in). In PDF output, frame="none" works fine, the rowsep and
colsep commands get somehow just ignored, i.e. in the PDF file the row and
column borders are still visible.

The xml-file looks as follows:

<?xml version="1.0" encoding="ISO-8859-15"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
               "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd";>
<book lang="de">
	<chapter>
		<title>Informaltable</title>
		<informaltable frame="none" rowsep="0" colsep="0">
			<tgroup cols="3">
				<tbody>
					<row>
						<entry>1.1</entry>
						<entry>1.2</entry>
						<entry>1.3</entry>
					</row>
					<row>
						<entry>2.1</entry>
						<entry>2.2</entry>
						<entry>2.3</entry>
					</row>
					<row>
						<entry>3.1</entry>
						<entry>3.2</entry>
						<entry>3.3</entry>
					</row>
				</tbody>
			</tgroup>
		</informaltable>
	</chapter>
</book>

I use SAXON Version 6.5.3 and FOP 0.20.5

I'm quite a DocBook novice so any help is appreciated!
Thanks,
Christof