How to query a temporary document in a variable

Hello xslt-users

I'm trying to use a temporary document as a lookup table with saxon
9.4 using xslt 2.0. The solution is also proposed in this
stackoverflow answer:
http://stackoverflow.com/questions/3626118/xslt-creating-a-map-in-xslt

But I'm not getting any results when I query the variable that holds
the temporary document:

<xsl:variable name="propertyMap">
	<entry key="foo">foo value</entry>
	<entry key="bar">bar value</entry>
</xsl:variable>

<xsl:template match="/">
	<xsl:value-of select="$propertyMap/entry[position() = 1]"/>
	<xsl:value-of select="$propertyMap/entry[@key='foo']"/>
	<xsl:value-of select="$propertyMap[1]"/>
</xsl:template>

The first two value-of expressions do not output anything, whereas the
third one outputs the whole propertyMap.

Any idea what I'm missing here?


Best regards,
James