CATIA STEP Core Interface 1 (ST1) helps you exchange data through a neutral format in a heterogeneous CAD/CAM environment. You can interactively read and write data in STEP AP214 and STEP AP203 data formats allowing reliable bi-directional data exchange between dissimilar systems. To facilitate access to data, CATIA Version 5 offers a homogeneous user interface for all supported formats, using Microsoft® Windows®-compliant user interface controls (such as File > Open, File > Save as) and automatic recognition of the STEP file type.