The exported data set needs to be closed. For example, an object representing a surface needs to be exported together with the objects that represent points on this surface. The query result, the objects created by GSMC, the root objects, and all objects representing attributes of the query result are collected by the Transitive Closure Generator (TCG). They form the closure of the root object of the CAD model. Finally, the data in the object set collected by TCG is encoded by STEP Exporter into a file in STEP/Part 21 standardized format that is sent to the CAD system. While the GSMC and the ROG modules depend on the EXPRESS information model for a particular application domain, the TCG and the STEP exporter are domain independent.