A recent working group dialog revealed that there was some confusion over what a product characteristic is and what a product family rating is. One approach to resolve this matter is to consult the definition for these terms in a dictionary or glossary created by a standards development organisation (SDO).
Finding definitions for terms
My favourite reference work is the IEC Glossary. The Glossary is the collected terms and definitions taken from IEC standards published since 2002. The ISO/IEC Directives require that the definition formulation shall be able replace the term in a sentence. This means the definition shall be a phrase and any definition starting with, for example, “the” shows the formulation group didn’t understand the rules and the ISO/IEC editors were asleep at the wheel when the document was edited at central office. Being a phrase is limiting, meaning that usually there is only room for the essential elements of the term to appear. Informative information can be relegated to additions like notes or examples.
The IEEE doesn’t have the phrase constraint allowing some IEEE definitions to look more like a chapter of a book. May be the IEEE-SA should apply the Twitter tweet restriction of no more than 140 characters.
Because many standards use the same term, the glossary contains many entries for a given term. For example the term “routine test” occurs 81 times in the Glossary at the time of writing this document. This means routine test is defined in at least 81 IEC standards. In the perfect world all the definitions would be the same, but the world isn’t perfect and people inadequately formulate, tweak and customise definitions.
Here is an example of a (claimed) customisation of the “term” definition in IEC 60050-151 by IEC SC37A WG5
routine test: test made on each SPD or on parts and materials as required to ensure that the product meets the design specifications
Published in: IEC 61643-11, ed. 1.0 (2011-03)
Source: IEC 60050-151:2001, 151-16-17 (modified)
Customisation proliferates definition variances, restricts usage of what should be generic item into a specific one with the potential of causing confusion. As terms and definitions are shown without the rest of the standard they occur in, the acronym SPD should have been explained by writing “surge protective device” in full. Likewise references to figures and clauses in a standard should be avoided.
What does the referenced IEC 60050-151 source definition look like?
routine test: conformity test made on each individual item during or after manufacture
Quite how IEC SC37A WG5 justifies their definition is a modification of the IEC 60050-151 one is an interesting debate. The IEC 60050-151 definition is an example of daisy chaining as you now need to find out what a conformity test is.
conformity test (compliance test): test for conformity evaluation
OK, one last time
conformity evaluation: systematic examination of the extent to which a product, process or service fulfils specified requirements
Bearing in mind the term can be replaced by its definition we have:
routine test: test for systematic examination of the extent to which a product, process or service fulfils specified requirements made on each individual item during or after manufacture
The two substitutions don’t quite work and that’s the problem with daisy chaining definitions, you need to check that replacement works.
When using the IEC Glossary it is important to pick the most relevant definition for your purpose with an emphasis on a generic definition rather than a customised definition. Next time we’ll get down to the business of looking up the definition of the term “characteristic”.