Hello!

Let's suppose we have an XML with some nested NODE nodes:

<root attr="first">
	<node id="1" attr="mike">
		<node id="2" />
		<node id="3" attr="dave" />
	</node>
	<node id="4">
		<node id="5" attr="peter" />
	</node>
</root>

What I want to achieve is to have an XSL that:
- takes a $id variable externally from a PHP script
- finds the node with @id=$id
- outputs the value "@attr" attribute IF PRESENT, otherwise the parent's 
"@attr" attribute IF PRESENT, otherwise the grandparent's... recursively 
traversing from parent to parent, until an @attr value is found

This won't work for some nodes:

<?xml version="1.0"?>
<xsl:stylesheet version="1.0">
     <xsl:output method="html" />
	<xsl:template match="root">
		<xsl:apply-templates select="//node[@id=$id]" />
     	</xsl:template>
	<xsl:template match="node">
             <xsl:choose>
		  <xsl:when test="not(@attr)"><xsl:apply-templates ".." /></xsl:when>
		  <xsl:otherwise><xsl:value-of select="@attr" /></xsl:otherwise>
		  </xsl:choose>
     </xsl:template>
</xsl:stylesheet>