[xsl] Error trapping in xsl

["dante" <dante@xxxxxxxxxxxxx>]

G'Day all,
This is my first post to this list so any help would be appreciated.
I'm trying to error trap for empty elements in the xml document
using xsl:choose & I can't work out the syntax.
The element <image_link> contains the data for the image attribute src
& when it's empty a broken image is shown.
What I would like it to do is show a null image instead.

Here's what it looks like so far:

<xsl:choose>
         <xsl:when test="foo"><!--ELEMENT CONTENT NOT EMPTY-->
                <!--SHOW IMAGE LINK VALUE-->
                <img><xsl:attribute name="src"><xsl:value-of
select="image_link" /></xsl:attribute></img>
         </xsl:when>
         <xsl:otherwise><!--ELEMENT CONTENT EMPTY-->
                <!--SHOW NULL IMAGE-->
                <img><xsl:attribute
name="src">null.gif</xsl:attribute></img>
        </xsl:otherwise>
</xsl:choose

Is this the best/only method to use?
Is there a way of error trapping for empty elements globally using xsl?
I'm using the msxml3 parser to output the xml document to ie5.5.

Thanks,
            Oliver Reid
            dante@xxxxxxxxxxxxx
            www.vianet.net.au/~dante



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