If the xlink:href attribute is being animated, the animatedInstanceRoot property contains the current animated root of the instance tree. If the xlink:href attribute is not currently being animated, animatedInstanceRoot contains the same value as the instanceRoot property.
For more information about the instance tree, see SVGElementInstance.
- Scalable Vector Graphics: Document Structure, Section 5.11.8
Microsoft Developer Network: [Windows Internet Explorer API reference Article]