STEP AP203 vs AP214 vs AP242: what is the difference and which STEP file format should you use?

Compared to proprietary, native file formats which restrict the opening and editing of files to native software like CATIA or SolidWorks, STEP files are neutral and interoperable. This means that they can be opened and edited across a variety of CAD and CAM software.

STEP, which is short for Standard for the Exchange of Product Data, is a popular neutral 3D CAD file format that is commonly used for sharing and exporting 3D CAD geometry. The STEP file format is interoperable amongst various CAD programs like SolidWorks, CATIA, NX, Creo, and Inventor.

STEP files have become the go-to file format for sharing part and assembly 3D CAD geometry with parties downstream from the design process like suppliers, subcontractors, and customers.

STEP is an ISO standard and is detailed into various Application Protocols (APs). As a CAD user, when you are exporting a part with the STEP format, you will have the option to choose which STEP AP variant to use.

This guide will discuss the different STEP AP variants and which one you should use when exporting your parts.

• AP 203 is the most basic STEP variant with the least export “extras”.
• This STEP format was concieved by the Aerospace industry for the purpose of “configuration-controlled 3D design”. The AP203 standard is primarily supported by the aerospace and defense industry.
• The STEP AP203 format defines the geometry, topology, and configuration management of solid models for parts and assemblies.

• The AP214 format was created and is supported by the Automotive industry for the purpose of conveying “core data for automotive mechanical design processes.”
• This STEP format includes all features of the AP203 format with the addition of colors, layers, geometric dimensioning and tolerances, surface conditions, kinematic structures, and design intent. AP214 is considered an extension of AP203.

• The AP242 format is the newest of the three and includes all the features of AP214 with several additions.
• New features included in the AP242 format include:
  • More complete Product and Manfucturing Information (PMI) including surface conditions and assembly-level PMI)
  • Improved interoperability with CAM software in regard to machined features
  • Tessellation, which allows the STEP file format to contain an efficient light visualization model of the part
  • Support for composite structures, electrical harnesses, and piping.
  • Improved PDM interoperability.
  • Kinematics and mechatronics interoperability.
• It is designed to be a modular file format, with ongoing development to implement new features.

If you are exporting a part from your CAD software and wondering which STEP format to use, it’s best to use the most full-featured STEP format that your software is able to export, starting with AP242. STEP AP242 is the first choice, followed by AP214 and then AP203.

Since AP242 is a newer format, it may not be an export option in some CAD software packages. In this case AP214 is the next best choice, as it offers additional appearance and GD&T export details beyond AP203.