StructuredDocumentTagRangeStart.placeholder property. Gets the [BuildingBlock](../../../aspose.words/buildingblock/) containing placeholder text which should be displayed when this structured document tag run contents are empty, the associated mapped XML element is empty as specified via the [StructuredDocumentTagRangeStart.xmlMapping](../xmlMapping/) element or the [StructuredDocumentTagRangeStart.isShowingPlaceholderText](../isShowingPlaceholderText/) element is ``true``....Markup class StructuredDocumentTa...