Purpose

Architecture of the Standard

Status and Planned Extensions

STEP Initial Release

STEP Subsequent Releases

Advantages of Current Specification

Implementation Issues

Implementation of APs

Software Tools

Implementation Levels

Testing

Training and Education

Purpose

STEP (Standard for the Exchange of Product model data) is the unofficial name for the ISO 10303 standards which are being developed by the International Organization for Standardization (ISO). STEP is formally called the "Industrial Automation Systems and Integration - Product Data Representation and Exchange Standard". In the United States, STEP is known as PDES which stands for "Product Data Exchange using STEP". PDES is the U. S. organizational activity that supports the development and implementation of STEP.

STEP is an international standard which is being designed to give a complete computer-interpretable representation of product data in a neutral format throughout the complete product life-cycle (design, engineering analysis, manufacture, support and maintenance, and disposal). This representation makes it suitable not only for file exchange but also as a basis for implementation, sharing, and archiving product databases.

With the proliferation of Computer-Aided Design, Computer-Aided Manufacturing, and Computer-Aided Engineering systems (CAD/CAM/CAE), all product data can be captured in digital form. The ability to transfer such product data in computer-readable format from one system to another is essential. Once the STEP standard is defined and implemented on various systems, then such systems can accept, use, and exchange product data so that developers, suppliers, vendors, and manufacturers will be able to receive and supply information about product parts and materials digitally. This will mean shorter development times, higher quality products, lower costs. It will also ensure flexibility and responsiveness to the needs of customers, manufacturers, suppliers, and users.

The STEP standards are fundamental to the CALS effort. CALS encompasses an architecture for Contractor integrated Technical information Services (CITIS) which requires an Integrated Weapon System Data Base (IWSDB). The STEP shared data environment will provide the kernel of the IWSDB and will support information access for prime contractors, sub-contractors, and the DoD. The scope of STEP standards development is immense with respect to the variety of products addressed.

Architecture of the Standard

STEP is organized as a series of Parts which are divided into six logical groups. Each of these groups is called a Class. Each Class has a unique function in STEP. Within each Class, documentation for each Part is being developed. STEP is being published as a set of inter-related standards, each of which falls into one of the six Classes:

• Overview (Parts 1 - 9) This Class provides an overview of all the STEP standards. Currently, only one part, Part 1- Overview and Fundamental Principles, has been developed. Other Parts in this Class may be developed in the future.
• Description Methods (Parts 10 - 19) This Class specifies the methods used to describe the information models found in both the integrated Resources Class and Application Protocols (AP) Class. Only one part, Part 11 - EXPRESS language, has been developed. The EXPRESS language provides the mechanism for the description of product data for both integrated resources and APs within STEP. This description is independent of any implementation method and will support all such methods defined in STEP consistently.
• Implementation Forms (Parts 20 - 29) This Class specifies the methods for exchanging and sharing data captured from information models.
• Conformance Testing (Parts 30 - 39) This Class specifies the methods that determine whether a STEP implementation conforms to the standard.
• Integrated Resources (Parts 40 - 199) This Class provides the specification of integrated conceptual information models for all of the STEP effort. Within this Class, there are two types of STEP Parts:
  1. Generic Resources (Parts 40 - 99) : These are Parts comprised of concepts and constructs that may be used by many applications, including the higher level Application Resources and APs.
  2. Application Resources (Parts 100 - 199): These are Parts containing conceptual constructs for specific application areas. These Parts may be used by many APs.
• Application Protocols (Parts 200 +) These Parts, the Application Protocols (AP), provide the mechanism both for specifying implementation requirements and for ensuring reliable information communication within the context of a given application. An AP is a complete specification of the context and scope for the use of product data in a particular domain using standardized integrated resources and other application specific entities. The AP also describes the conformance requirements and test purposes from which its abstract test suite is derived. Parts in this Class are numbered 200 and above.

Status and Planned Extensions

STEP Initial Release

Twelve STEP Parts were registered for Draft International Standard (DIS) status in May 1993. This initial release of STEP provides capabilities for the exchange of two-dimensional drafting product data and the configuration controlled exchange of three-dimensional product definition data with emphasis on mechanical parts and assemblies.

• Part 1 - Overview and Fundamental Principles
• Part 11 - EXPRESS Language Reference Manual
• Part 21 - Clear Text Encoding of the Exchange Structure
• Part 31 - Conformance Testing Methodology
• Part 41 - Fundamentals Product Description and Support
• Part 42 - Geometric and Topological Representation
• Part 43 - Representation Structures
• Part 44 - Product Structure Configuration
• Part 46 - Visual Presentation
• Part 101 - Drafting
• Part 201 - Explicit Drafting
• Part 203 - Configuration Controlled Design

STEP Subsequent Releases

Subsequent STEP releases will provide added functionality and extend the capabilities of the Parts in the initial Release. The schedule for these STEP subsequent releases has not been determined. The following Parts are currently being developed.

• Part 22 - STEP Data Access Interface (SDAI)
• Part 32 - Test Laboratory Requirements
• Part 33 - Structure and Use of Abstract Test Suites
• Part 34 - Abstract Test Methods
• Part 45 - Materials Products
• Part 4~ - Shape Tolerances
• Part 48 - Form Features
• Part 104 - Finite Element Analysis
• Part 105 - Kinematics
• Part 202 - Associative Drafting
• Part 204 - Mechanical Design Using Boundary Representation
• Part 205 - Mechanical Design Using Surface Representation
• Part 206 - Mechanical Design Using Wireframe Representation
• Part 20~ - Sheet Metal Die Planning and Design
• Part 208 - Life Cycle Product Change Process
• Part 209 - Design Through Analysis of Composite & Metallic Structures
• Part 210 - Electronic Printed Circuit Assembly: Design and Manufacture
• Part 211 - Electronic Printed Circuit Assembly: Test, Integrated Diagnostics and Remanufacture
• Part 212 - Electrotechnical Plants
• Part 213 - NC Process Plans for Machined Parts
• Part 214 - Core Data for Automotive Mechanical Design
• Part 215 - Ship Arrangements
• Part 216 - Ship Molded Forms
• Part 217 - Ship Piping Systems
• Part 218 - Ship Structures
• Part 219 - Dimensional inspection Process Planning

Advantages of Current Specification

STEP is an extremely broad specification, including virtually every data item required to develop, analyze, manufacture, document, and support products ranging from mechanical products to electronic products to large structures such as ships and buildings, etc.

STEP is a conceptual specification for communicating product information at all stages in a product's life cycle, covering all aspects of product description and manufacturing specifications. The fundamental components of STEP are product information models and specifications to exchange information corresponding to these product models. STEP will provide tools to reduce time to market, reduce costs, improve quality, and continuously improve processes. STEP will allow all information from finance, marketing, engineering, manufacturing, support, etc. to work together and share data. STEP data is open: it is independent of the applications or systems that create it, and is accessible to and usable by any other applications that need to use it.

STEP will provide the ability to turn data into meaningful information to support decision making. STEP will provide a foundation for the next generation of open systems.

Implementation Issues

The initial Release of DIS STEP is available for implementation. The emphasis on software applications is currently focused on creating Application protocols (APs) which are focused on high value industrial processes.

Implementation of APs

APs are the implementable parts of STEP. Many APs are in the planning or development stages. Guidelines for the development of APs are documented and are available through the U. S. Product Data Association. When an AP is proposed for development, approval is required from the IGES/PDES Organization (IPO). The AP proposal requires a precise definition of scope and a detailed plan for development. The development of the AP proceeds in accordance with the STEP guidelines. The draft AP is reviewed and balloted through the international standards process.

Software Tools

There is a growing recognition of the need for software tools to facilitate the STEP standards development, application software implementation, and testing process. Software tools can be catalogued in four major groupings.

• Standards development tools: Parsers, compilers, editors, schema generators, etc.
• STEP data exchange tools: Software to generate and interpret STEP physical files and databases, etc.
• Data management tools: STEP data access interfaces and database management software, etc.
• End User Tools: Translators, etc.

Implementation Levels

STEP provides a wide variety of levels for system implementation. Implementation levels are particular ways of storing, exchanging or accessing information which are distinguished by the degree of data sharing. Those levels may include the following:

• Exchange File - Product data is exchanged between computer systems or applications using STEP exchange files which are defined in STEP Part 21. The structure of the exchange file is derived from the conceptual data model's EXPRESS definition. It is expected that the early use of STEP will involve using exchange files to move data between systems.
• Database - Product data is stored and accessed in databases based on various database architectures (such as relational or object-oriented) This database level will allow application developers to create, manipulate, and share STEP data, based on standard data models and system interfaces. Applications use a standard query language such as SQL or standard interfaces such as the STEP Data Access Interface (SDAI) defined in Part 22.
• Data Access - Product data can be accessed independently of the storage method used.

Testing

The STEP testing activities are categorized as follows:

• Standards testing: it addresses the quality of the evolving STEP specification itself. These validation efforts provide assurance that the methods employed by STEP will indeed work, and that the standard provides a means to meet the functionality that it claims to support.
• Component testing: This is the preliminary testing conducted by the STEP software implementor to verify that the application software addresses both the basic requirements imposed for compliance with the standard and the users' functionality requirements.
• Conformance testing: it evaluates a software product with respect to the specifications provided in a Part of a STEP standard and tests for the presence of these characteristics required by the standard itself. STEP includes the specifications for Conformance testing as a requirement built into many Parts of the standard.
• Acceptance testing: it is concerned with the user's specific requirements. It tests a software product against a set of requirements defined by the users of that software product. This type of testing may include performance, user interfaces and inter-operability with other systems.

  Current efforts are primarily focused on developing methods for Conformance and Standards testing. Component and Acceptance testing activities have just gotten underway within the vendor and user communities.

  Training and Education

  The STEP standard is technically complex and requires different types of skills for the development of the standard, as well as, its implementation in a production environment. Training has been focused on the highly technical needs of the developers. As industry proceeds from the standards development stage to testing and implementation, additional types of training are needed for the new users, new developers, and even experienced staff. More formal, structured training programs will be required to effectively transfer the needed information to users.

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