How to Represent a Visual Speciication?

We consider the representation of a visual speciication within a highly integrated environment which provides specialized support for the associated visual language. We state that such an environment needs to represent a visual speciication at four levels in order to perform its tasks: (1) the physical layout, (2) the pictorial structure, (3) the abstract structure , and (4) the representation of the meaning. Furthermore, we will show how graph grammars, constraint solving, and attribute evaluation can be used to keep the representations up-to-date with each other. It will turn out that deening the structure at diierent levels and deening the visual syntax are in fact two names for the same thing.