The Battle of the Non-Significant Number
by Stefan Schaefer
I started here at CargoLifter in January 2000, with the challenging task to install CM from scratch using a PDM tool. Since CargoLifter was a new company, I had no legacy systems to fight with except for the mental legacies of about 200 engineers. These were very real "Legacies," fed by each engineer's experiences at such large companies as Dornier, Boeing and General Electric. After much discussion, it was decided to take the classical CM approach. It was also decided to use a non-significant number for all objects (documents, parts, etc.), and to put all of the significances of each object into its attributes.
When this discussion was taking place at CargoLifter, I remembered the heated discussions at the CMII Conference in San Diego where there was an afternoon "debate" session entitled, "Pros and Cons of Significant Numbering." . As a result of my experience in San Diego, I was absolutely happy with my company's decision to use a non-significant number for all objects and wrote a CargoLifter CM Instruction about the way we would identify the different objects.
The Human Machine Interface
The idea to identify an object or document just by a (nonsignificant) number and put all other information into the attributes of that object is clearly very hard for managers and engineers to understand. When we started at CargoLifter, I often heard the plea that "we need new document numbers because just a PDM number is not sufficient to identify a document."
In attempting to resolve these complaints in a professional manner, I received some requirement documents concerning a "Document Number." In
them, there were recommendations for the following kinds of information to be included as part of the document (or object) number:
• Product where the document is applied
• Serial number of the product
• Project identifier
• Belonging ATA Chapter (Air Transport Association for O&M documentation)
• Originating organization unit
• Document type code
• Document revision level
• Documentation level
The resulting numbering schemes that embodied these kinds of information generally did so to make it easier (for humans) to identify and retrieve a document. In the CargoLifter arena, one major argument that was often put forward was that the aircraft industry is special, and that it is necessary to have an "intuitive" kind document number structure because the certification authorities require it.
There were many long discussions at CargoLifter regarding the above kind of "significant" numbering systems compared with non-significant numbering systems. Finally, we (our PDM Team and CM Team) were able to strike a workable compromise with the larger community. The identification term will be a mixture of document-related significances (attributes) and non-significances. While MOST of the attributes would be available in the PDM tool, some key attributes would appear as part of the identification term. We also convinced the users (engineers and manufacturing personnel) not to use any product-related attributes.
After much discussion, a mutual agreement was reached whereby our PDM Team created some more necessary (key) attributes. With our customers, the design and production engineers, we defined the mandatory inputs and automated links. Thus, the final CargoLifter document number: an identification term which may look significant, but it is nothing more than a non-significant number related to an object, mixed with a limited set of defined attributes associated with the object itself. Once agreed, the PDM Team generated a customer-oriented user interface with pull-down menus to make this work . . . and it does.
Mr. Stefan H. Schaefer, CMIIC, PMP; is President of the German speaking CMII Usergroup serving Austria, Germany, Liechtenstein and Switzerland. He is the Section Manager for Configuration Management at CargoLifter Development GmbH; Mr Schaefer holds a University Degree in Systems Engineering from the University of Applied Sciences in Esslingen (Germany). He has over 12 years of experience in development and production-oriented Configuration Management.
Institute of Configuration Management Scottsdale, AZ 85261-5656 Tel: (480) 998-8600 Fax: (480) 998-8923 Email: info@icmhq.com