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No training program I've undertaken refers to 10,000 as an emergency descent altitude. None of the companies or agencies for whom I've flown used it, and the arbitrary altitude that we've always used at Flight Safety and Simuflite courses has been 14,000', excepting where higher terrain or MEA intervenes.
Well just to throw another number into the mix, "my" 777 Ops manual, which is supposedly a direct lift from Boeing, says "MSA or 15000 feet (10000 feet if fuel endurance is not critical) whichever is higher..."