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  Harvey  Betty 
  Tucker  Hugh 
 

STEP/SGML Standards Working Together

 

Abstract:

  ISO 10303, Standard Exchange for Product Data (STEP), is being developed by a broad range of industries to provide extensive support for modeling, automated storage schema generation, life-cycle support, plus many more data management facilities. ISO 8879, Standard Generalized Markup Language (SGML), and the SGML family of standards, includingHyTime (Hypermedia-Time-based Structuring Language, ISO 10744) andDSSSL (Document Style Semantics and Specification Language) , is used for the documentation of products. These two standards, STEP and SGML, are used in the same industries and companies. STEP is used during product development and manufacturing, where as SGML products are usually created during the final processes of product development.
 This paper will discuss current initiatives in industry and government organizations for incorporating SGML product information during the beginning of the product development cycle. Several different initiatives from various corporations will be discussed. The benefits of each of the different methodologies will be discussed and analyzed.
 The STEP standard task group, Product Documentation (ISO 184/SC4/WG3/T14) is currently tasked with the responsibility for creating a methodology for the cooperation of the STEP and SGML standards. Information will be provided about how current corporate initiatives could impact and provide pertinent input in the T14 Working Group.
 

Introduction

 ISO 10303, Standard Exchange for Product Data (STEP), is being developed by a broad range of industries to provide extensive support for modeling, automated storage schema generation, life-cycle support, plus many more data management facilities. ISO 8879, Standard Generalized Markup Language (SGML), and the SGML family of standards, including HyTime and DSSSL, is used for the documentation of products. These two standards, STEP and SGML, are used in the same industries and companies. STEP is used for exchange of product data during the entire product lifecycle. Product documentation is usually created during the final stages of the product development.
 Many industries and individual corporations are currently in the process of defining methodologies for including product documentation in SGML both during the product development cycles, and through the entire life-cycle of the product.
 

Why Integrate Industrial Data and Product Documentation

 Today most organizations that are creating product are also creating product documentation. Most consumer products, from the food we eat to the automobiles we drive have product documentation associated with the product. The documentation usually starts being compiled at the time the product is being designed and developed.
 The documentation that is developed at the time of the design and development of a given product is often not used in the development of the product documentation. Product documentation is typically developed at the end of the product development cycle. The engineers who developed the product and the technical writers who create the technical documentation often do not communicate together.
 It is more efficient to generate a great deal of the product documentation during the design, development and implementation of a product. The larger the amount of product documentation that is developed in the front-end of the product development cycle, the greater the benefit to the organization.
 The engineer(s) who are developing a product are the most knowledgeable individuals about that product and are in the best position to supply information about the product. Information created by the engineer(s) is more likely to be accurate.
 It is important to understand at this point that we are not talking about replacing the technical writer. The technical writer will still add value to the documentation. The information will still require expert writers and editors to provide the technical documentation to the end-user in a meanful and understandable format.
 

Why STEP and SGML

  The answer to the question 'WhySTEP (Standard Exchange for Product Data) and SGML?' seems obvious to us. Both STEP andSGML (Standard Generalized Markup Language) are:
 
  • ISO Standards
    •  
  • Used within the same organizations
    •  
  • STEP models product while SGML models documents
    •  
  • Readily available tools
    •  Both standards play different but related roles in information management. Each role is already well defined within the information architecture of an organization.
     

    How STEP and SGML Can Work Together

     STEP and SGML/HyTime can work very well as companion standards. STEP does a very good job of modeling product data.
      STEP is a relatively new ISO standard. It became a standard in 1992. It is an information exchange standard that allows information to be exchanged between different CAD systems. Initially it was a standard that involved modeling product or processing geometry. However, as STEP is beginning to implemented and used in the commercial, government and military areas organizations are beginning to focus on STEP for its standard modeling capability. STEP uses a modeling language called EXPRESS for creating models. The EXPRESS language allows user definedentities . Eachentity has a unique ID similar to ID's used within SGML.
     Unlike SGML, the STEP standard doesn't have the capability of reuse of data by referencing or addressing the data. For instance, if you wanted to reuse a circle within your EXPRESS model, you would have to copy the entire contents of the entity that defined the circle, whereas in SGML if you wanted to reuse an object you would reference that object. Figure 1 shows how STEP requires an object to be copied whereas SGML allows the object to be referenced.
     
     Although the addressing mechanism of SGML cannot be used within the EXPRESS model, if SGML, which includes HyTime capability can be facilitated within the STEP model the robust addressing capabilities of HyTime can be used. SGML and HyTime can be used asenabling technologies to supply technical information concerning the product. HyTime can be used to reference specific objects within a STEP model.
     

    Current Industrial Initiatives (ISO/TC184/SC4/WG3/T14)

     Currently there is an ISO standard task group assigned to look into the possibility of integrating the SGML standard within the STEP environment. As organizations are beginning to implement STEP they are beginning to see the value of allowing SGML within the STEP environment. They see that they can greatly decrease theirtime to market by establishing information capturing mechanisms at the beginning at the bottom of the product development cycle.
     There are currently two proposals for including SGML information within the STEP architecture.
     
    1. The first allows a new entity type within STEP called the 'SGML_string'. The 'SGML_string' will allow SGML information to be embedded within the STEP architecture. Figure 2 shows how the SGML information can be embedded within a STEP model using the 'SGML_string' concept.
     
      The 'SGML_string' construct is an easy but powerful mechanism for including intelligent information within the STEP environment. Currently text strings are allowed within STEP but there isn't a mechanism for including 'intelligent' text. The 'SGML_string' construct will allow reusable Information Objects to be defined.
     Todays information paradigm has shifted from the time when we were only dealing with the information printed on paper. When information is only delivered on paper we think of this information as a document -cover-to-cover. Today we think of information as it really is, reusableinformation objects. This means that our information can be taken to a wide range of products and media:
     Media
     
  • paper
    •  
  • CD-Rom
    •  
  • Internet/Intranet
    •  Product
     
  • Technical Manuals
    •  
  • User Manuals
    •  
  • Computer Based Training
    •  
  • On-line help
    •  
  • And many more....
    •   The second method would require a technical documentation Application Protocol (AP). STEP has provided an architecture and methodology for the development of application protocols (APs). An AP is a standards document (a part of ISO 10303) that provides for delivery of information in a well defined application context. The use of an AP ensure that the information conveyed is that which was intended. An AP is to STEP what a DTD is to SGML. One approach that has been discussed within ISO STEP is to develop an AP specifically for technical documentation.
     There is a high probably that both of the above methods will be pursued and that both will be used within the STEP architecture. The first approach will allowinformation objects , i.e., procedures, tasks, warnings, etc. to be embedded within any AP. The second approach, a technical documentation AP, will define how technical documentation will be organized within the STEP environment. Information from the 'SGML_string' can be used and referenced within the technical documentation AP.
     

    Future Issues

     As this initiative moves forward there are emerging technological advances that are being made that will need to be monitored, as well as implemented into the solution. Some of the new technologies that are being watched carefully by the TC14 committee are DSSSL and XML. Specifically, XML looks like it may be a good mechanism for moving forward with the 'SGML_string' construct.
     A major question about incorporating SGML into the STEP environment is where will the DTD or DTD fragments (if we are talking aboutinformation objects reside within the 'SGML-string' construct. With the work that is being done with XML, it may be possible to put the onus of the DTD at the authoring component and eliminate the need for incorporating the DTD into the STEP model. Technically this concept brings up its own challenges and concerns but the problem becomes simpler than trying to have the DTD and SGML declaration residing within the STEP model.
     

    Conclusion

     The work currently being done by the TC14 group is breaking new ground and is really exciting. The possibility of these two information standards working together will be of great benefit to major industry players.
     If you are interested in learning more about the work of the TC14 group or becoming a member of the committee, information about the working group can be found at URL:http://www.eccnet.com/step . There is also an exploder list that is available and all are welcome to join. To join the TC14 exploder list send an e-mail to step@eccnet.com with the word 'SUBSCRIBE' in the subject list. Your name will be added to the list.
     

    ACKNOWLEDGEMENTS

     
      NOTE:
     Developing Application Protocols (APs) using the architecture and methods of STEP (STandard for the Exchange of Product Data), William F. Danner, Computer Integrated Construction Group, NIST, October 1996
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