A class 3 neutronic fuel carrier was the designation used to classify a type of 23rd century transport capable of hauling several metric tons of neutronic fuel as well as several hundred passengers.
In the Kobayashi Maru scenario, the Kobayashi Maru was a 3rd class neutronic fuel carrier. (Star Trek II: The Wrath of Khan)
The sidebar data was extracted from the display graphic appearing in the scenario describing the Kobayashi Maru. In dialog it was referred to as a "3rd class" carrier, whereas on the display it was referred to as a "Class III" carrier.
