<xsl:variable name="isHTML" select="exists(/html)" as="xs:boolean"/>


which might, depending on whether you have changed the default xpath
namespace, and whether you are using xhtml or html-as-xml, need to be




<xsl:variable name="isHTML" select="exists(/h:html)" as="xs:boolean"/>


with xmlns:h="http://www.w3.org/1999/xhtml"

David

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