What is Data Unification
To optimize the UPR data structures, during design we study the semantics of each data type of the supported CAD systems and identify data types that are of similar semantics. Initial semantics assumptions are made according to the CAD system's user guide, and are modified after extensive empirical usage of the CAD system by experienced users. Data types that are finally considered similar share data structures.
Data unification is only an optimization. When data types are incompatible, they are not unified and are handled through rewrites (see below). This stands in sharp contrast to previous methods, in which each and every data type is 'unified' by adopting a 'standard' definition