because the second one is not listed as ADO16. Should I add it?
Lots of cars are missing details.
The boxes are to specify in which part of the model name you want to search. The first is the common "commercial" model name. The second ("chassis") is the internal code used by the factory and by the fans, like ADO16 in this case (or the W-codes of Mercedes, E-codes of BMW, etc.)
The last one is a field that usually holds extra info like body special info, type of vehicle, nickname, etc.