It seems exclude-result-prefixes needs to be explicity set for each
imported stylesheet, rather than using the value in the importing
stylesheet - is that right?

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:xs="http://www.w3.org/2001/XMLSchema"
 exclude-result-prefixes="xs">

<xsl:template match="/">
	<xsl:call-template name="foo"/>
</xsl:template>

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xsl:template name="foo">
	<foo/>
</xsl:template>

Is there any reason why the exclude-result-prefixes value isn't taken
from the importing stylesheet?  Not the biggest issue I know, just
struck me as odd.