Inclusion of other name spaces

Hi, 

I have an XML document in the FO name space, starts like this:
<xsl:template match="/">
		<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">


So I have blocks like this:

<fo:table table-layout="fixed">
	<fo:table-column column-width="30mm"/>
	<fo:table-column column-width="52mm"/>
		<fo:table-body>
	<fo:table-row>
	<fo:table-cell>
	<fo:block><fo:external-graphic
rc="url('{$oa.ContextURL}/xsl/site/images/{$hospitalLogo}')" height="25mm"
width="auto"/></fo:block>
	</fo:table-cell>
	</fo:table-row>
	<!-- can I do this in here? -->
	<mynamespace:anotherfield>blah blah blah</mynamespace:anotherfield>
	<mynamespace:anotherfield2>more blah</mynamespace:anotherfield2>
	</fo:table-body>
	</fo:table>


So the issue is can I simply put new data into the existing XSL file to
generate my XSL-FO XML output or do I need to define the "mynamespace"
somewhere? 

As in a previous post I want to do this to stop the content from being in
the FO namespace so it doesn't print it. 

Thanks

Alan