But I though ISO standards were, in fact, standards, set by the International Standards Organisation. If every film maker can measure speed by their own method, how can they call it ISO? Companies can't define their own ISO 4000 quality standard!(posted 8159 days ago)Even if the "standard" was set for high contrast (which is what I remember too), that's really not going to double a film speed. They're just overdeveloping it, which ups contrast but doesn't usually do a lot to the 0.1 over b+f speed point.
There is an ISO document ISO 6:1993 "Photography -- Black-and-white pictorial still camera negative film/process systems -- Determination of ISO speed" which I presume contain the ISO film speed definition, but the contents of the document don't seem to be available on the web (unless you pay ISO 44 swiss francs to see them!).