Air to Boil test in diesel engine cooling system

[Uncia_Uncia]

Hello All,
I am intrigued by term Air to Boil temperature to measure cooling capacity in diesel engine.
As per def
ATB= TTT ( Max. top tank temp)- Tco (Coolant temp. out of engine)+ Ambient air temp

I am trying to understand, how ATB defines cooling capacity.
If TTT= 107 , Tco =90 and Ta= 29,

ATB= 46
What does this number 46 celsius reveal about cooling capacity?

Thanks

 

[lucky-guesser]

"The main goal of the ATB test is to evaluate the maximum efficiency of the system. It is important, therefore, to
define the vehicle characteristics such as motorization, weight, maximum load, and the place where this vehicle will be
sold (due to the climate and altitude parameters). The ATB index represents the maximum temperature that the cooling
system supports before the coolant begins to boil. If the temperature exceeds this limit, the cooling system should be
better dimensioned or the maximum load of the vehicle should be reduced."

Taken from page 6:

https://abcm.org.br/anais/encit/2008/artigos/11_5472.pdf

 

[Uncia_Uncia]

Hello lucky-guesser,
I find that document online but still I am not actually getting what will happen if in above example ATB temp is below 46 or above 46.
I found one good document about it.
Do we want temperature above ATB or below ATB?
if above ATB why it needs to be above?

 

[Uncia_Uncia]

Finally, I understood.
Thanks