code: @Override
      public void appendXMLToMasterStyle(final XMLUtil util, final Appendable appendable)
              throws IOException {
          RegionFooterHeader
                  .appendRegionXMLToMasterStyle(util, appendable, this.leftRegion, "region-left");
          RegionFooterHeader
                  .appendRegionXMLToMasterStyle(util, appendable, this.centerRegion, "region-center");
          RegionFooterHeader
                  .appendRegionXMLToMasterStyle(util, appendable, this.rightRegion, "region-right");
      }
docs: Used in file styles.xml, in <office:master-styles>,<style:master-page />.
  
  @throws IOException If an I/O error occurs