one single, complete, implementation-independent Product Information Model, which shall be the Master Record of the integrated topical and application information models". But because of the complexity, the standard had to be broken up into smaller parts that can be developed, balloted and approved separately. In 1994/95 ISO published the initial release of STEP as international standards (IS) with the parts 1, 11, 21, 31, 41, 42, 43, 44, 46, 101, AP 201 and AP 203. Today AP 203 Configuration controlled 3D design is still one of the most important parts of STEP and supported by many CAD systems for import and export. In the second phase the capabilities of STEP were widely extended, primarily for the design of products in the aerospace, automotive, electrical, electronic, and other industries. This phase ended in the year 2002 with the second major release, including the STEP parts AP 202, AP 209, AP 210, AP 212, AP 214, AP 224, AP 225, AP 227, AP 232. Basic harmonization between the APs especially in the geometric areas was achieved by introducing the Application Interpreted Constructs (AIC, 500 series). A major problem with the monolithic APs of the first and second releases is that they are too big, have too much overlap with each other, and are not sufficiently harmonized. These deficits led to the development of the STEP modular architecture (400 and 1000 series). This activity was primarily driven by new APs covering additional life-cycle phases such as early requirement analysis (AP 233) and maintenance and repair (AP 239), and also new industrial areas (AP 221, AP 236). New editions of the previous monolithic APs on a modular basis have been developed (AP 203, AP 209, AP 210). The publication of these new editions coincided with the release in 2010 of the new ISO product SMRL, the STEP Module and Resource Library, that contains all STEP resource parts and application modules on a single CD. The SMRL will be revised frequently and is available at a much lower cost than purchasing all the parts separately. In December 2014, ISO published the first edition of a new major Application Protocol, AP 242 Managed model based 3d engineering, that combined and replaced the following previous APs in an upward compatible way: AP 201, Explicit draughting. Simple 2D drawing geometry related to a product. No association, no assembly hierarchy. AP 202, Associative draughting. 2D/3D drawing with association, but