A relative number denoting an evaluation of rate of spread, or suppression difficulty for specific combinations of fuel, fuel moisture and wind speed. This data is then indexed into comparative FDIs based on the regions within NSW
New South Wales Rural Fire Service (NSWRFS), Dictionary/Terminology, Granville, NSW, Australia 2010. http://www.rfs.nsw.gov.au/dsp_content.cfm?cat_id=1 049, (For Fr - Brit) {170}