I am not sure these classifications are outdated because we have come so far along. I just think we have more individuals in this community, for what ever reason, are thinking more about how fires are investigated, asking more specific questions, and bringing these issues to light. I think your right that a lay person may see a conflict with an undertermined fire cause and an accidental determination. More or less classifications/descriptors or consistency between reporting agencies may not be the problem. I think this discussion has identified that communication is the solution. What is "undetermined" mean? Does the context matter (e.g. public vs. private investigations)? I would venture a guess that we will see this issue in a proposal in the next revision cycle of NFPA 921.

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com