Application Protocols (APs) are used to exchange data. Each AP pertains to a different application area. For example, AP227 pertains to spatial plant technology and contains several entities pertaining to that area, such as pipe or elbows. Also, these APs use certain common entities known as generic resources, such as geometry and topology, to define solid models.

AP203 applies to representations of mechanical parts and assemblies. AP214 applies to representations of data relating to automotive design. Present day AP203 files typically contains the boundary representation model, assembly data, and a limited amount of other product information. AP214 files typically contain colors, layers, and generic resources.

Following methods of dealing with the shape of an assembly provided by STEP AP203 are supported.

1. Replicating the shape of the components in the shape of the assembly.
2. Mapping the shape of the component into the shape of the assembly.
3. Referencing the shape of the component.

The boundary representation of a model is a CAD model represented by its boundary. For example, a surface model consists of only the surfaces use to make the model. Solid models include geometry information, such as surfaces, curves, and points, and topology information, such as edges, vertices, and faces. The geometry information provides data about the form of the model, and the topology information provides the connectivity between these geometric elements and the extent of the geometric elements.

You can import a STEP file by choosing File > Import > Exchange File Types > STEP (*.stp) or by using the key-ins IMPORT AP203 or IMPORT AP214. The Import STEP AP203/AP214 File dialog, a standard file selection dialog, opens. After you select the file you want to import, the second Import STEP AP203/AP214 File dialog opens, which is used to change a log filename or directory, and also to change the import settings.

You can export STEP data by choosing File > Export > Exchange File Types > Step (*.stp) or by using the key-ins EXPORT AP203 or EXPORT AP214. After identifying and accepting an element, the Export STEP AP203/AP214 File dialog opens, which is used to change a log filename or directory, and also to change export settings.