Image by sylvar
Hazmatspotting is one of my hobbies: when I see a truck with a hazardous-materials placard, I check the number against the Emergency Response Guidebook (I keep a list on my PDA, adding details about when and where I first spotted it). This truck is carrying diesel fuel, although #1993 is a bit of a catchall — it can include "liquid disinfectant, n.o.s. (not otherwise specified)", "cosmetics, n.o.s.", "drugs, n.o.s.", etc. This is okay because you’d respond to a spill of any of these things in roughly the same way.