Structureddocumenttag.placeholder property. Gets the [BuildingBlock](../../../aspose.words/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 [Structureddocumenttag.xmlMapping](../xmlMapping/) element or the [Structureddocumenttag.isShowingPlaceholderText](../isShowingPlaceholderText/) element is ``true``....placeholder property StructuredDocumentTa.placeholder property...as specified via the StructuredDocumentTa.xmlMapping element or...