specifications

This section contains additional details on the object specifications. As mentioned in Section 3, we rely on the PB language to define the structure for each object type that we would like to handle with our model. Our framework supports all basic constructions of the language including nested messages and oneofclauses. For example, in Listing 1b, we can see that a generic Objectcan be either an entityor a constraint. We also use oneoffor objects that may appear in several mutually exclusive configurations (e.g., CircleArcEntityrepresents both arcs and closed circles and for the latter which it does not make sense to specify end points). We handle such constructions by injecting an additional token with the discrete value set to the index of the active field.