Is this node, the document root... best test?

<xsl:template match="*" mode="someTemplate">
 <xsl:choose>
   <!-- Method (1) -->
   <xsl:when test="not(parent::*)">
     This works, but is it safe/efficient?
   </xsl:when>
   <!-- Method (2) -->
   <xsl:when test="string(name(parent::*)) = ''">
     This works, but is it safe/efficient?
   </xsl:when>
   <xsl:otherwise>This node, is *NOT* the root node...</xsl:otherwise>
 </xsl:choose>
</xsl:template>

PPS I want to be careful, that I don't try and match the
   node's "name" against the document root node's "name",
   as this may provide a false match.