Know About STEP

STEP Application Protocols

A list of the STEP Application Protocols (AP) as of June 2004 is given in Fig.2. The ability to support many protocols within one framework is one of the key strengths of STEP. All the protocols are all built on the same set of Integrate Resources (IR's) so they all use the same definitions for the same information. For example, AP-203 and AP-214 use the same definitions for three dimensional geometry, assembly data and basic product information. Therefore CAD vendors can support both with one piece of code.

Part 201 Explicit Drafting
Part 202 Associative Drafting
Part 203 Configuration Controlled Design
Part 204 Mechanical Design Using Boundary Representation
Part 205 Mechanical Design Using Surface Representation
Part 206 Mechanical Design Using Wireframe Representation
Part 207 Sheet Metal Dies and Blocks
Part 208 Life Cycle Product Change Process
Part 209 Design Through Analysis of Composite and Metallic Structures
Part 210 Electronic Printed Circuit Assembly, Design and Manufacturing
Part 211 Electronics Test Diagnostics and Remanufacture
Part 212 Electrotechnical Plants
Part 213 Numerical Control Process Plans for Machined Parts
Part 214 Core Data for Automotive Mechanical Design Processes
Part 215 Ship Arrangement
Part 216 Ship Molded Forms
Part 217 Ship Piping
Part 218 Ship Structures
Part 219 Dimensional Inspection Process Planning for CMMs
Part 220 Printed Circuit Assembly Manufacturing Planning
Part 221 Functional Data and Schematic Representation for Process Plans
Part 222 Design Engineering to Manufacturing for Composite Structures
Part 223 Exchange of Design and Manufacturing DPD for Composites
Part 224 Mechanical Product Definition for Process Planning
Part 225 Structural Building Elements Using Explicit Shape Rep
Part 226 Shipbuilding Mechanical Systems
Part 227 Plant Spatial Configuration
Part 228 Building Services
Part 229 Design and Manufacturing Information for Forged Parts
Part 230 Building Structure frame steelwork
Part 231 Process Engineering Data
Part 232 Technical Data Packaging
Part 233 Systems Engineering Data Representation
Part 234 Ship Operational logs, records and messages
Part 235 Materials Information for products
Part 236 Furniture product and project
Part 237 Computational Fluid Dynamics
Part 238 Integrated CNC Machining
Part 239 Product Life Cycle Support
Part 240 Process Planning


Each Application Protocol includes a scope describing its purpose, an activity diagram describing the functions that an engineer needs to perform within that scope, and an Application Requirement Model describing the information requirements of those activities. These information requirements are then mapped into the common set of Integrated Resources and the result is a data exchange standard for the activities within the scope.

The ultimate goal is for STEP to cover the entire life cycle, from conceptual design to final disposal, for all kinds of products. However, it will be a number of years before this goal is reached. The most tangible advantage of STEP to users today is the ability to exchange design data as solid models and assemblies of solid models. Other data exchange standards, such as the newer versions of IGES, also support the exchange of solid models, but less well.

STEP led the way with three dimensional data exchange by organizing an implementation forum for the CAD vendors so that they could continually improve the quality of the solid model data exchanges. The history of this success is relatively interesting because it show that the initial reluctance of vendors to implement user-defined standards can be overcome with enough perseverance.

At first, in 1996, there was a significant body of opinion that solid model geometry data could not be exchanged between systems using a neutral standard. However, in 1997 Ford, Allied Signal and STEP Tools, Inc. demonstrated the first successful data exchange of 3D geometry using STEP. Once this basic capability had been demonstrated a pilot project, called AeroSTEP, was organized by Boeing and its Aircraft engine vendors to test the first translators by exchanging data about where an engine fits onto the airframe. This project started out by exchanging simple faceted models but eventually demonstrated the exchange of models with great complexity.

The AeroSTEP project made it clear that STEP data exchange of solid model data was both feasible and valuable. As a result, vendor neutral implementation forums were formed in Europe, the Far East and the USA and the quality of the translators was raised to the level that allowed anyone, including ordinary users in small organizations, to use STEP for data exchange of solid models after about 2001.