Synopsis

    <xsl:attribute-set name="foil.subtitle.properties">
      <xsl:attribute name="font-family">
        <xsl:value-of select="$slide.title.font.family"></xsl:value-of>
      </xsl:attribute>
      <xsl:attribute name="text-align">center</xsl:attribute>
      <xsl:attribute name="font-size">
        <xsl:value-of select="$foil.title.master * 0.8"></xsl:value-of><xsl:text>pt</xsl:text>
      </xsl:attribute>
      <xsl:attribute name="space-after">12pt</xsl:attribute>
    </xsl:attribute-set>