An Anchor node creates a group that acts as a clickable anchor where every child node in the group is displayed, and
clicking one follows a url to another scene or another Web link.
An Anchor can also bring the user to another Viewpoint location in the scene.
A description field names each Anchor so that the user knows its purpose.
These X3D scenes are adapted directly from the
original VRML 2.0 Sourcebook chapter examples.
Introduction to VRML97 SIGGRAPH98 course notes.