Dynamic itemset labels

Hi

Can anyone tell me if the use of a XPath function within label/@ref, to return a literal value should work? This is what I have tried in the usual browsers, to no avail:

<xfm:itemset nodeset="person">
	<xfm:label ref="concat(surname, ' ', fornames)"/>
	<xfm:value ref="."/>
</xfm:itemset>

All the best

Mark