Remarks on STEP

From: Martin Geiger (Fraunhofer Gesellschaft)
To: RP-ML
Date: Friday, February 4, 1994
Subject: Remarks on STEP
Hi folks,
     during the IMS conference and the EARP meeting there was mentioned that the persons working in RP 
mostly are not good informed about STEP. I can not say that I understand much about STEP. Nevertheless I take the chance to bring in some basic information before I start with a travel of some weeks:
     Some remarks on step 
     In the beginning (1984) the development of the 'Standard for the Exchange of  Product Model Data' (STEP) was intended to be a standard only for the  exchange of data between CAD systems. Now STEP is on the way to becoming a  logically complete information model for the whole product data processing from  storage to administration and exchange. STEP is developed and standardized in  the working groups TC 184 SC4 of the International Standardization Organization  (ISO) on the base of ASCII files. The specification of STEP is realized with  the language EXPRESS (an independent data definition language with the  characteristics of Pascal and C++). An important advantage of EXPRESS is that  it provides a computer processible representation of a product model.  Conformance testing, syntax testing and software development can be done with  EXPRESS.
     The product model of STEP can be divided into three partial models.
		The kernel of the product data model is the "Fundamental of  Product Description and 
Support". This partial model contains the organization  and administration of the product data.
		The application independent partial model describes all common  product data such as 
geometry, topology, features, materials, tolereances,  etc.. (integrated sources)
		The application dependent partial model includes models for  technical drafting, ship 
structures, electrical functional, finite element  analysis and kinematics. (application resources)
     Application Protocols serve for the interpretation and realization of these  partial models in applications (processors, data bases, etc.). The world wide  development of them is increasing.
     The demands on STEP have strongly increased and the appointed time for an ISO  standard delayed. 
Meanwhile the standardizing process is going on (draft  version of first STEP parts in January 1993) and so STEP has a good chance to  become a technological base for the internal and external product data  processing in industry. To get from the present implementation of local  solutions to a common product data model will be a hard and long way. Indeed,  there are differing opinions as to whether such an implementation is useful. However, it is clear that future developments in RP without attention to STEP  could turn out to be a great mistake.
     More information and the actual STEP parts are available at a public library by an ftp-server. The adress is: ftp.cme.nist.gov or 129.6.32.54
Greetings
Martin