John,
The STEP 203 does not support mass properties. Here is an intrinsting article about the STEP files.
What do engineers need to know about STEP?
Engineers do not need to acquire an in-depth knowledge of STEP, but it will be beneficial to them to know how it works in general terms. STEP provides a neutral data format for the exchange of CAD/CAM/CAE models and PDM data -- which is generically referred to as "product data".
It is also useful to know that there are essentially two "levels" at which STEP can be used, which I will call Levels A and B (this is a simplification of the 4 levels of implementation that were originally conceived for STEP ... which I will not describe here, since they are more technical and require more knowledge of STEP "internals"):
Level A: STEP File Exchange
At this level, one buys CAD/CAM/CAE tools that have STEP translators and uses the translators to exchange data between tools via STEP files. STEP file exchange currently supports data exchange between tools capable of reading/writing the same STEP Application Protocol (AP), which -- since all mature commercial STEP translators currently are based on AP 203, which supports configuration-controlled 3D design -- enables models to be exchanged MCAD-to-MCAD and MCAD-to-Analysis (for some analysis tools, such as MSC Patran, that can read AP 203 files). In the future, as more STEP translators are implemented and more AP's are added to STEP, STEP files will support exchanges of other types of data (e.g., FEA data) between similar tools, as well as exchanges of data between different types of tools (e.g., ECAD-to-MCAD, etc.). However, to fully leverage the Product Data Management capabilities inherent in STEP's data structures, a Level B implementation is necessary.
Level B: STEP Database Application
A STEP database application can take many forms, from a simple database that stores and manages STEP files to a sophisticated Product Data Management (PDM) system that uses the STEP data structures as the core of its database schema. The power of utilizing the STEP data structures is that the database application then has "internal knowledge" of the models it is managing, even though they were originally created in proprietary formats on COTS CAD/CAM/CAE tools.
The Level B STEP capability is beyond the current state of the art of COTS PDM tools, although several OEM's (Boeing, Lockheed Martin, and IBM, for example) have proprietary in-house systems that are beginning to implement that type of capability -- which they, quite rightly, regard as a significant competitive edge. Of course, NASA's in-house systems will never be as sophisticated as Boeing's or Lockheed Martin's, but to implement the collaborative and highly integrated engineering environments needed for the next generation of NASA missions requires advanced PDM capabilities that can only be implemented properly, from a software engineering perspective, using an internal database schema that maps invertibly to the most important STEP Application Protocols.
IMPORTANT: Level B requires Level A. STEP translators must be available for the CAD/CAM/CAE tools that are used, so that their models can be translated to STEP for management within the STEP-based database application.
-Hora
