IStructuredDocumentTag.placeholder property. Gets the [BuildingBlock](../../../aspose.words.buildingblocks/buildingblock/) containing placeholder text which should be displayed when this SDT run contents are empty, the associated mapped XML element is empty as specified via the [IStructuredDocumentTag.xml_mapping](../xml_mapping/) element or the [IStructuredDocumentTag.is_showing_placeholder_text](../is_showing_placeholder_text/) element is true.... append_child ( aw . Section ( glossary_doc...substitute_block . first_section . append_child ( aw . Body ( glossary_doc...