ISO 10303 is an ISO standard for the computer-interpretable representation and exchange of product manufacturing
information.
Its official title is: Automation systems and integration — Product data representation
and exchange.
It is known informally as "STEP", which stands for "Standard for the Exchange of Product
model data".
ISO 10303 can represent 3D objects in Computer-aided design and related information.
Overview The international standard's objective is
to provide a mechanism that is capable of describing product data throughout the life
cycle of a product, independent from any particular system.
The nature of this description makes it suitable not only for neutral file exchange, but also
as a basis for implementing and sharing product databases and archiving.
Typically STEP can be used to exchange data between CAD, computer-aided manufacturing,
computer-aided engineering, product data management/enterprise data modeling and other CAx systems.
STEP is addressing product data from mechanical and electrical design, geometric dimensioning
and tolerancing, analysis and manufacturing, with additional information specific to various
industries such as automotive, aerospace, building construction, ship, oil and gas,
process plants and others.
STEP is developed and maintained by the ISO technical committee TC 184, Automation systems
and integration, sub-committee SC 4, Industrial data.
Like other ISO and IEC standards STEP is copyright by ISO and is not freely available.
However, the 10303 EXPRESS schemas are freely available, as are the recommended practices
for implementers.
Other standards developed and maintained by ISO TC 184/SC 4 are:
ISO 13584 PLIB - Parts Library ISO 15531 MANDATE - Industrial manufacturing
management data ISO 15926 Process Plants including Oil and
Gas facilities Life-Cycle data ISO 18629 PSL- Process specification language
ISO 18876 IIDEAS - Integration of industrial data for exchange, access, and sharing
ISO 22745 Open technical dictionaries and their application to master data
ISO 8000 Data quality STEP is closely related with PLIB.
History The evolution of STEP can be divided into
four release phases.
The development of STEP started in 1984 as a successor of IGES, SET and VDA-FS.
The initial plan was that "STEP shall be based on one single, complete, implementation-independent
Product Information Model, which shall be the Master Record of the integrated topical
and application information models".
But because of the complexity, the standard had to be broken up into smaller parts that
can be developed, balloted and approved separately.
In 1994/95 ISO published the initial release of STEP as international standards with the
parts 1, 11, 21, 31, 41, 42, 43, 44, 46, 101, AP 201 and AP 203.
Today AP 203 Configuration controlled 3D design is still one of the most important parts of
STEP and supported by many CAD systems for import and export.
In the second phase the capabilities of STEP got widely extended, primarily for the design
of products in the aerospace, automotive, electrical, electronic, and other industries.
This phase ended in the year 2002 with the second major release, including the STEP parts
AP 202, 209, AP 210, AP 212, AP 214, AP 224, AP 225, AP 227, AP 232.
Basic harmonization between the APs especially in the geometric areas was achieved by introducing
the Application Interpreted Constructs.
A major problem with the monolithic APs of the first and second release is that they
are too big, have too much overlap with each other and are not sufficiently harmonized.
These deficits lead to the development of the STEP modular architecture.
This activity was primarily driven by new AP covering additional life-cycle phases such
as early requirement analysis and maintenance and repair, and also new industrial areas.
New editions of the previous monolithic APs on a modular basis have been developed.
The publication of these new editions coincide with the release of the new ISO product SMRL,
the STEP Module and Resource Library, in 2010 that contains all STEP resource parts and
application modules on a single CD.
The SMRL will be revised frequently and is available at a much lower cost than buying
all the parts separately.
At the end of 2010 the seventh Change Request of the SMRL has been worked out.
In mid 2010 the development of the new major AP 242 Managed model based 3d engineering
was initiated.
The first edition of AP242 is expected to be technically complete in 2011 and is dedicated
to replace the most successful STEP APs 203, 214 and other APs in the mechanical design
area in an upward compatible way.
In particular it will contain major updates in the area of Geometric dimensioning and
tolerancing, Kinematics, and Tessellation.
Future editions of AP242 will extend the scope further into areas such as electrical harnesses.
Structure
STEP is divided into many parts, grouped into Environment
Parts 1x: Description methods: EXPRESS, EXPRESS-X Parts 2x: Implementation methods: STEP-File,
STEP-XML, SDAI Parts 3x: Conformance testing methodology
and framework
Integrated data models The Integrated Resources, consisting of
Parts 4x and 5x: Integrated generic resources Parts 1xx: Integrated application resources
PLIB ISO 13584-20 Parts library: Logical model of expressions
Parts 5xx: Application Interpreted Constructs Parts 1xxx: Application Modules
Top parts Parts 2xx: Application Protocols
Parts 3xx: Abstract Test Suites for APs Parts 4xx: Implementation modules for APs
In total STEP consists of several hundred parts and every year new parts are added or
new revisions of older parts are released.
This makes STEP the biggest standard within ISO.
Each part has its own scope and introduction The APs are the top parts.
They cover a particular application and industry domain and hence are most relevant for users
of STEP.
Every AP defines one or several Conformance Classes, suitable for a particular kind of
product or data exchange scenario.
To provide a better understanding of the scope, information requirements and usage scenarios
an informative application activity model is added to every AP, using IDEF0
STEP is primarily defining data models using the EXPRESS modeling language.
Application data according to a given data model can be exchanged either by a STEP-File,
STEP-XML or via shared database access using SDAI.
Every AP defines a top data models to be used for data exchange, called the Application
Interpreted Model or in the case of a modular AP called Module Interpreted Models.
These interpreted models are constructed by choosing generic objects defined in lower
level data models and adding specializations needed for the particular application domain
of the AP.
The common generic data models are the basis for interoperability between APs for different
kinds of industries and life cycle stages.
In APs with several Conformance Classes the top data model is divided into subsets, one
for each Conformance Class.
The requirements of a conformant STEP application are:
implementation of either a preprocessor or a postprocessor or both,
using one of the STEP implementation methods STEP-File, STEP-XML or SDAI for the AIM/MIM
data model and supporting one or several conformance classes
of an AP.
Originally every APs was required to have a companion Abstract test suite, providing
Test Purposes, Verdict Criteria and Abstract Test Cases together with example STEP-Files.
But because the development of an ATS was very expensive and inefficient this requirement
was dropped and replaced by the requirements to have an informal validation report and
recommended practises how to use it.
Today the recommended practises are a primary source for those going to implement STEP.
The Application Reference Models is the mediator between the AAM and the AIM/MIM.
Originally its purpose was only to document high level application objects and the basic
relations between them.
IDEF1X diagrams documented the AP of early APs in an informal way.
The ARM objects, their attributes and relations are mapped to the AIM so that it is possible
to implement an AP.
As APs got more and more complex formal methods were needed to document the ARM and so EXPRESS
which was originally only developed for the AIM was also used for the ARM.
Over time these ARM models got very detailed till to the point that some implementations
preferred to use the ARM instead of the formally required AIM/MIM.
Today a few APs have ARM based exchange formats standardized outside of ISO TC184/SC4:
PLM-Services within the OMG for AP 214 ISO 14649 Data model for computerized numerical
controllers for AP 238 PLCS-DEXs within OASIS for AP 239
There is a bigger overlap between APs because they often need to refer to the same kind
of products, product structures, geometry and more.
And because APs are developed by different groups of people it was always an issue to
ensure interoperability between APs on a higher level.
The Application Interpreted Constructs solved this problem for common specializations of
generic concepts, primarily in the geometric area.
To address the problem of harmonizing the ARM models and their mapping to the AIM the
STEP modules were introduced.
They contain a piece of the ARM, the mapping and a piece of the AIM, called MIM.
Modules are built on each other, resulting in an directed graph with the AP and conformance
class modules at the very top.
The modular APs are: AP 203, Configuration controlled 3D design,
TS and 2nd edition AP 209, Composite and metallic structural
analysis and related design AP 210, Electronic assembly, interconnect
and packaging design AP 221, Functional data and schematic representation
of process plants AP 236, Furniture product data and project
data AP 239, Product life cycle support
AP 241, Generic Model for Life Cycle Support of AEC Facilities
AP 242, Managed model based 3d engineering The modular editions of AP 209 and 210 are
explicit extensions of AP 203.
Coverage of STEP Application Protocols The STEP APs can be roughly grouped into the
three main areas design, manufacturing and life cycle support.
Design APs: Mechanical:
AP 201, Explicit draughting.
Simple 2D drawing geometry related to a product.
No association, no assembly hierarchy.
AP 202, Associative draughting.
2D/3D drawing with association, but no product structure.
AP 203, Configuration controlled 3D designs of mechanical parts and assemblies.
AP 204, Mechanical design using boundary representation AP 207, Sheet metal die planning and design
AP 209, Composite and metallic structural analysis and related design
AP 214, Core data for automotive mechanical design processes
AP 235, Materials information for the design and verification of products
AP 236, Furniture product data and project data
AP 242, Managed model based 3d engineering
Connectivity oriented electric, electronic and piping/ventilation:
AP 210, Electronic assembly, interconnect and packaging design.
The most complex and sophisticated STEP AP.
AP 212, Electrotechnical design and installation.
AP 227, Plant spatial configuration
Ship: AP 215, Ship arrangement
AP 216, Ship moulded forms AP 218, Ship structures
Others: AP 225, Building elements using explicit shape
representation AP 232, Technical data packaging core information
and exchange AP 233, Systems engineering data representation
AP 237, Fluid dynamics has been cancelled and the functionality included in AP 209
Manufacturing APs: AP 219, Dimensional inspection information
exchange AP 223, Exchange of design and manufacturing
product information for cast parts AP 224, Mechanical product definition for
process plans using machining features AP 238 - Application interpreted model for
computer numeric controllers AP 240, Process plans for machined products
Life cycle support APs: AP 239, Product life cycle support
AP 221, Functional data and schematic representation of process plants
AP 241, Generic Model for Life Cycle Support of AEC Facilities
The AP 221 model is very similar to the ISO 15926-2 model, whereas AP 221 follows the
STEP architecture and ISO 15926-2 has a different architecture.
They both use ISO-15926-4 as their common reference data library or dictionary of standard
instances.
A further development of both standards resulted in Gellish English as general product modeling
language that is application domain independent and that is proposed as a work item for a
new standard.
The original intent of STEP was to publish one integrated data-model for all life cycle
aspects.
But due to the complexity, different groups of developers and different speed in the development
processes, the splitting into several APs was needed.
But this splitting made it difficult to ensure that APs are interoperable in overlapping
areas.
Main areas of harmonization are: AP 214 and 203 in the area of 3D mechanical
design.
AP 214 took over all of the functionality of the earlier AP 203 edition and then extending
the capabilities significantly.
The second edition of AP 203 took over bigger parts of AP 214 by adding again new functionality.
The upcoming AP 242 will formally replace AP 203, 214 and other mechanical design APs
AP 201, 202, 212, 214, 221 and now AP 203 ed 2 for technical drawings with extension
in AP 212 and 221 for schematic functionality AP 214, 224 and 238 for machining features.
AP 203ed2, 210, 214, 224, 238 for Geometric dimensioning and tolerancing
For complex areas it is clear that more than one APs are needed to cover all major aspects:
AP 212 and 214 for electro-mechanical products such as a car or a transformer
AP 203/214, 209 and 210 for electro/electronic-mechanical products
AP 212, 215, 216, 218, 227 for ships AP 203/214, 224, 240 and 238 for the complete
design and manufacturing process of piece parts.
See also Boundary representation
Geometric dimensioning and tolerancing References
External links Standardization group ISO TC184/SC4
List of STEP parts STEP Ship team ISO TC 184/SC 4/WG 3/T 23
The STEP Module Repository on SourceForge CAx Implementor Forum - information on existing
implementations and testing activities STEP Application Handbook: ISO 10303, North
Charleston, SC: SCRA, 30 June 2006 WikiSTEP - tutorial and overview information
about STEP and recommended practices PDES, Inc. - recommended practices and links
Korea STEP Center Product Life Cycle Support Resources
AP 224 implementation Introducing STEP
PDM schema - a common subset extracted from AP 203 and AP 214
STEP-OAGIS Harmonization BRLCAD and STEP
STEP File Analyzer - generate a spreadsheet from a STEP file, also checks for some CAx-IF
recommended practices STEP programs
http:www.steptools.comstandard/ http:stpviewer.comDefault.aspx
http:stlviewer.orgDefault.aspx http:igsviewer.comDefault.aspx