[cableshaft]

Have a source for that? I can't find a mention of that anywhere.

[jfengel]

I apologize: the USDA uses only the 2 hour rule. The 2/4 hour rule is common in most of the rest of the world, most prominently in Australia, e.g.: https://timestrip.com/2-hour-4-hour-rule-haccp-plans/