On WWW servers links are uni-directional, i.e., the link is only specified in the source document, and the destination document has no idea that there is a link pointing to it. In Hyperwave, links are bi-directional , which means that both the source anchor and the destination anchor know of each other. This is all done automatically by the server. In addition to supporting link maintenance, Hyperwave's separate link data base also provides additional advantages. First, it allows the author to add links to arbitrary documents, like images, 3D scenes, mpeg movies, etc.
Users can even add private annotations to documents.
Both source and destination anchors can be arbitrary parts of documents, like an individual word in a text, an part of an image, a frame of a movie, or an object in a 3D scene. On the World Wide WWW, the destination anchors always have to be an entire document. This kind of link management allows for the production of local maps . Since hypertext documents often have a very complicated structure, a global map, which shows all documents on the server, would be much too confusing. For educational purposes this means that teachers could add additional links which are only visible to them, and not to the students.