ABSTRACT
The information exchange is characterized by two data transformations: One transformation from the native format of the source system to the standard exchange format and one transformation from the standard exchange format to the native format of the destination system. Due to incompatible data schemes this process normally results in the loss of data that accumulates during each information exchange. Available Computer Aided Design (CAD) systems store their models in an evaluated form as objects and attributes. The chapter introduces the new research project opCAD. The objective of this project is the standardization of CAD in civil engineering by a language for unevaluated CAD models. In available CAD systems the user stores the result of the construction process at certain points in time. In the new approach the sequence of operations executed in the construction is described by a language to be developed in the research project.
