<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="xml" indent="yes"/>
<xsl:template match="@* | node()">
<xsl:copy>
<xsl:if test="self::* and ancestor::*[local-name()='book'] and not(@id)">
<xsl:attribute name="id">
<xsl:value-of select="generate-id()"/>
</xsl:attribute>
</xsl:if>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>