The STEP file is a neutral 3D Computer Aided Design (CAD) file format that can exchange data among different CAD programs like Creo, Inventor, CATIA, and more. STEP is an acronym which means Standard for the Exchange of Product Data). The popularity of the STEP file has grown among engineers and developers. This is because of its features and benefits.
This file format is an ISO standard. The EXPRESS modeling language is mainly used in writing this file. STEP is in various Application Protocols (APs). These include STEP AP203 vs AP214, vs AP242. The classification of these APs varies as regards their 3D dimensional geometry and mechanical CAD design. We will take a look at the differences and similarities in STEP AP203 vs AP214 vs AP242 in this article. Also, we will discuss the benefits and features of each of these APs.
What is the Importance of the STEP File Format?
The STEP file format is mainly designed to enable interoperability among several CAD programs. Let’s take a look at some scenarios where this file format is important. It is not easy to translate Native CAD file formats generated from CAD software to another proprietary CAD system. Therefore, the STEP file format comes in handy in this case. You only need to export the proprietary file formats into a neutral CAD format.
STEP has become popular among companies. This is because companies are now moving away from traditional paper-based workflows and are now adopting model-based definitions. These companies now make use of the STEP file format for interoperability downstream. Among several companies, the STEP 242 is the most popular file format.
STEP AP 242 contains production manufacturing information like BOM, GD&T, and notes for measuring and building assembly. With this, you can now get different workflows from one source of truth. The STEP file is compatible with many programs and as such makes collaboration quite easy.
STEP files are commonly used in architectural design and 3D modeling. This is because they offer cross-platform compatibility and a high level of accuracy. Also, STEP files can help you design well-detailed models. A good number of manufacturers use the STEP file due to the benefits it offers.
Each 3D STEP file has 3D model data which are saved in an ASCII text format. One of the amazing features of STEP file is that it can read and save the entire body of the 3D model with precision.
STEP Application Protocols

Each application protocol features a scope that defines its purpose. This is an activity diagram that specifies what an engineer needs to do within the scope. Also, there is an Application Requirement Model that defines the data requirements of the activities.
The most common use of STEP file format is the exchange of design data as assemblies of solid models. STEP became a more popular choice with its 3D dimensional data exchange by setting up a forum for Cad vendors to enhance the quality of the solid model data. This success shows that enough perseverance can overcome the reluctance of vendors to adopt user-defined standards.
In 1996, it was believed that it is impossible to use neutral standards to exchange solid model geometry data between systems. STEP Tools, Inc in collaboration with Ford, Allied Signal showed how STEP was successful in exchanging data of 3D geometry. This was really a huge success.
What is STEP AP203?
AP refers to Application Protocol. For AP203, the design of mechanical parts and configuration controlled 3d are crucial. AP 203 specifies the management data of solid models for mechanical assemblies. The defense and aerospace sectors support this file format. Also, this file format doesn’t allow the management of Layers and Colors.
The second edition of AP203 is interoperable with STEP AP214. In this edition, there is an inclusion of layers and colors. Also, there are textual annotations related to geometry in this edition. You will also find validation properties like center, volume, area, and clouds of points.
Features of STEP AP 203 include:
- Geometrical data as faceted models, solids, wireframe, and surface models.
- The products are mechanical assemblies and parts
- It features data linked to documentation of security classification
- There are data for configuration control
What is STEP AP214?
This Application protocol is for data for automotive mechanical design processes. STEP AP 214 receives support from the automotive industry. It defines every important detail in AP 203. Details such as layers, geometric dimensioning and tolerance, and plus colors of STEP 203. Also, this file format enables the management of layers and colors.
AP214 is an improved version of AP203. In 2003, STEP introduced a second edition of STEP 214. No changes were introduced in the scope but some corrections were made. STEP is already preparing the third edition of this format.
The features of this AP214 are all from AP 203. There are other features like
- Geometric dimensioning and tolerance (GD&T)
- Colors and layers
- Construction history which is in 3D format
- Validation properties which are Global and local
- Textual annotations related to geometry
- Kinematic structures
- References to product data in another format other than STEP
- Surface conditions and tolerance data
What is STEP AP 242?
STEP AP 242 has an application protocol that focuses on managed model-based 3D engineering. It makes a single standard for 3D engineering by combining STEP AP 214 and STEP AP 203. STEP AP242 includes all the features of AP 214 and AP 203. This makes it a more popular option among all the STEP file formats. It is a highly preferred STEP format for businesses.
STEP AP 242 features 3D electrical harness, 3D semantic PMI, 3D piping, 3D kinematics assembly, and 3D shape quality. Also, it has digital rights management and mechatronics.
STEP AP242 features the same shape presentation which is implemented in the CAD tool for STEP AP214. Another uncommon feature you will find in AP242 is the tessellated shape representation. This feature enables display in 3D shape by making use of a representation like triangulated faces. There is a semantic representation in STEP AP242.
What are the Differences Between STEP AP203 vs AP214 vs AP242?

Out of all the STEP APs explained above, the best format is the STEP AP 242. This is because it includes both the features of STEP AP 214 and STEP AP 203. Also, STEP AP 242 is an ideal format as it is a proof for MBE or MBD workflows. The ISO/TC 184/SC 4 has withdrawn its contribution towards AP214 and AP203.
The introduction of publication of AP242 made AP 203 and AP214 to be deprecated. STEP users can track the implementation coverage of AP242 by following the work of CAx.
Furthermore, AP 203 and AP214 are very popular for model geometry. This is because the MBE or MBD workflow has just been adopted. The difference between STEP AP203 vs AP214 vs AP242 can be seen in their features. Also, in terms of applications, STEP AP203 vs AP214 vs AP242 differ.
STEP File Viewer
The National Institute from Standards and Technology (NIST) created the STEP File Viewer. It is a free tool that enables users to open the STEP file. Also, this tool enables users to open this file to perform some functions like generation of CSV files or a spreadsheet that comprises attribute information
Also, this tool enables users to create a view of supplemental geometry, part geometry, and targets, graphical PMI annotations. Users can as well make analysis of any graphical PMI, semantic PMI, and validation features for conforming to recommended practices.
What STEP Alternatives are Available?
Asides from STEP file formats, there are a lot of CAD-neutral file formats you can make use of. Although the STEP file offers a lot of features, other file formats are also a great alternative for developers.
JT
JT is specially designed for visual representation. However, it can consist of PMI and B-rep. This makes it MBD-ready. The majority of vendors use the JT Open Toolkit of Siemen which uses blends alongside proprietary recipes. Therefore, it is only popular within Siemen software environments.
IGES
IGES refers to the Initial Graphics Exchange Specification. This neutral file format is the oldest and it enables exchange of data among CAD systems. It enables solids and geometry. But, it has no PMI and as such, it isn’t MBD-ready. IGES allows users to exchange product models in the form of wireframe and circuit diagrams.
QIF
QIF means Quality Information Framework. As a more recent ISO standard format, it has the largest scope on MBD. This is particularly for Big Data, semantic PMI for human and machine-readable CAD. QIF has some advanced concepts such as measurement and tolerancing features. This format is well used within the aerospace and defense sector, all thanks to its advanced MBE/MBD workflows.
3D PDF
This file format is very ubiquitous and easy to view on every device. You can use it for graphical representation. However, it doesn’t enable automation since it has no machine-readability features. The 3D PDF features 3D geometry. Since this file is very easy to read, it makes the distribution downstream much easier.
How does STEP Help Geometric Dimensioning and Tolerancing?
In manufacturing, you need something beyond the geometric model to produce a part. Many additional specifications are needed, but a description of the tolerances is very important. This is because it will help in deciding the manufacturing process and as well as the tools needed in manufacturing the part.
When AP203’s second edition was created, STEP included a model of Geometric Tolerance and Dimension (GD&T) information. GD&T was further improved in AP242. There has been several changes and CAD vendors have made feedback about functionality.
The new model of GD&T features an existing model since the GD&T data qualifies items in the geometry model. It is quite challenging to implement the GD&T model.
Applications of STEP Files
In 3D design, STEP file has become a standard. This file is commonly used in printing, architecture, and manufacturing among others. STEP file can do the following:
Share 3D models
STEP files were mainly created to make it very easy to share files that comprise 3D data. Developers use these files to print or review 3D models. STEP files have complete 3D models instead of the geometries and as such, sharing of files is very simple. Also, these files are compatible with various CAD systems.
Edit 3D models
In STEP, all three dimensional (3D) components are saved as one. You can use these components to create some design edits. The majority of CAD programs can read and edit STEP files. This enables collaboration and cross-platform design.
Frequently Asked Questions
What are the Disadvantages of STEP Files?
CAD software can’t identify STEP files since they don’t have the necessary texture or material data that makes them identifiable. This is not ideal for architectural design. Creating a STEP file can be time-consuming and as such, this makes it very complex.
STEP files don’t store camera or lighting information. File formats like USDZ and FBX can help you represent lighting and camera setups.
How do you Open, Create, and Edit a STEP file?
You can open a STEP file by using different CAD programs. All you need to do is to locate the STEP file and right-click to select File. After that, choose Open and the file will open. If the STEP file refuses to open, there is a need to open or install the STEP file or CAD.
Creating a STEP file is as simple as editing one. When creating a STEP file, you will need to use the CAD program. After this, you can now edit your file.
Which is the best option between STEP AP203 vs AP214 vs AP242?
When it comes to STEP AP203 vs AP214 vs AP242, the best option is the AP242. This is because it has the features of both STEP AP203 and AP214.
Conclusion
STEP AP203 vs AP214 vs AP242 are common STEP file formats used in different applications. These file formats serve different functions and are used in different applications. Despite the differences in STEP AP203 vs AP214 vs AP242, these file formats share some similarities.