What does the asterisk symbol (*) represent in the DOT hazardous materials segregation table at 49 CFR 177.848(d)-(e)?

49 CFR 177.848(e); cross-reference to 177.848(f) Class 1 compatibility table

Explosives compatibility is more nuanced than a simple X/O rating can capture, since different compatibility groups within Class 1 have their own specific rules for what can and can't travel together. The asterisk exists precisely to route explosives questions to that more detailed table instead of the general one.