This stylesheet must be indepedent of the XML source, therefore will
be a named template or a match="/" template. The problem in both cases
is that will be no context node to parse the xml:lang attribute.

                       <xsl:for-each select="/*">
                           <xsl:call-template name="PageFoot" />
                       </xsl:for-each>

(or, if you prefer, put the <xsl:for-each select="/*">
around the <xsl:choose> in the PageFoot template)

HTH,
Anton