for STEP conversion use AP203 or AP214?
AP203 applies to representations of mechanical parts and assemblies. AP214 applies to representations of data relating to automotive design. so what does this means exactly?
the USA the most commonly implemented protocol is called AP-203. This protocol is used to exchange data describing designs represented as solid models and assemblies of solid models. In Europe a very similar protocol called AP-214 performs the same function.
The original intent of STEP was to publish one integrated data-model for all life cycle aspects. But due to the complexity, different groups of developers and different speed in the development processes, the splitting into several APs was needed. But this splitting made it difficult to ensure that APs are interoperable in overlapping areas. Main areas of harmonization are:
AP 214 and 203 in the area of 3D mechanical design. AP 214 took over all of the functionality of the earlier AP 203 edition and then extending the capabilities significantly. The second edition of AP 203 (published in 2011) took over bigger parts of AP 214 by adding again new functionality. The upcoming AP 242 will formally replace AP 203, 214 and other mechanical design APs
AP 201, 202, 212, 214, 221 and now AP 203 ed 2 for technical drawings with extension in AP 212 and 221 for schematic functionality
AP 214, 224 and 238 for machining features.
AP 203ed2, 210, 214, 224, 238 for Geometric dimensioning and tolerancing(source http://en.wikipedia.org/wiki/ISO_10303)