What do the laser classes 3R and 3B mean?

Class 3R: increased risk on direct viewing of the beam, but the natural blink reflex usually still provides sufficient protection. Safety goggles are recommended but not strictly required in all cases. Maximum 5 mW in the visible range. Class 3B: direct radiation is hazardous to the eye, but diffuse reflections are usually harmless. Safety goggles are mandatory in the open beam area. Beam enclosure where possible, clear marking of laser areas, training of personnel. Maximum 500 mW. Both classes require a laser safety officer in commercial use.