Conversion from CATPart to CATIA V6 (3D XML) is not supported yet :(

CATPart is a native format developed by Dassault Systems for storing parts of the assemblies created in CATIA V5 software suite, which is extensively used in mechanical engineering including aerospace, automotive, shipbuilding and other domains.

CATPart stores geometry, structure and metadata of 3D models dedicated to single parts. Multiple CATPART files can be combined into a CATProduct assembly file.

Among CAD applications that support CATPart extension are Autodesk Inventor, Fusion 360, and 3ds Max.

3DXML is an open-standard proprietary 3D file format developed and supported by Dassault Systemes. 3DXML files are typically created as exports from Dassault Systemes' 3DEXPERIENCE application. The 3DXML file is a zip archive file consisting of a BOM file and one or more 3D representations stored in either XML or binary format. Compact file size allows users to transfer 3D XML quickly and embed it into websites, emails, and various MS Office documents. Therefore, the format is commonly used to integrate 3D data into technical documentation.