The transfer of CAD data among different CAD systems or subsequent downstream analysis applications is critically important to the acceleration of the product development cycle. Since each vendor has its own proprietary native file format, this transfer of data among differing systems is difficult at best. A proposed solution to the transfer problem was the development of agreed upon standard neutral file formats, such as IGES or STEP. However, each vendor writes its own "flavor" of IGES and STEP files that other applications may not understand.;The research presented in this dissertation bridges a gap between these systems by taking a native IGES or STEP file and either repairing the data or adding missing information so that a downstream application can properly interpret the model. This ensures that the receiving system gets a full and accurate NURBS-based representation: the original surfaces, the corresponding full complement of model space trim curves, and the corresponding full complement of parameter space trim curves. With all the information present, the receiving system can select the needed pieces to reconstruct the model.