CATPRODUCT file is used by CATIYA V5 software application. This software is used for developing and designing of a 3D sketch or model of any object. 

When two or different objects are opened in a single environment and they are mated with each other the single file containing all these elements and their details is called assembly file. In CATIYA the assembly file is saved with the extension of CATPRODUCT. As the object file saves the detailed information of the single object, assembly file saves the designing specifications, surface details, mesh construction, node connections and other properties of all the elements or objects that are used in making a assembly.