Minecraft wiki entry for Block_entity_format, associated text: : The block entity's root tag.
 isPowered: Whether this structure block is being powered by redstone.
 data: Unknown.
 redstoneSaveMode: The current redstone mode of this structure block.[more information needed]
 xStructureOffset: X-offset of the structure.
 yStructureOffset: Y-offset of the structure.
 zStructureOffset: Z-offset of the structure.
 xStructureSize: X-size of the structure.
 yStructureSize: Y-size of the structure.
 zStructureSize: Z-size of the structure.
 structureName: Name of the structure.
 dataField: Unknown.
 ignoreEntities: Whether entities should be ignored in the structure.
 includePlayers: Whether players should be included in the structure.
 removeBlocks: Whether blocks should be removed in the structure.
 showBoundingBox: Whether to show the structure's bounding box to players in creative mode.
 rotation: Rotation of the structure.[more information needed]
 mirror: How the structure is mirrored.[more information needed]
 animationMode: The mode of animation.[more information needed]
 animationSeconds: Unknown.
 integrity: How complete the structure is that gets placed.
 seed: The seed to use for the structure integrity, 0 means random.[needs testing]