Thank for your reply David. Following on from your suggestions, I've had a
little play, and one of the nice features of pivotdiragrams is adding a
shape to the node. However, the image is not retained if you remove and
then re-add the category. I'm wondering if:
1) Its possible to add a shape and control it via an attached data source
2) Is there a way to keep the applied shape attached to the node
