IStructuredDocumentTag.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 [IStructuredDocumentTag.xmlMapping](../xmlMapping/) element or the [IStructuredDocumentTag.isShowingPlaceholderText](../isShowingPlaceholderText/) element is true....BuildingBlock containing placeholder text which should be displayed when...contents as a custom placeholder text for a structured document tag...