If you want a soldier to be 'nearestObjected' you put the type of the soldier in the "type", i.e. "SoldierWB" (basic western soldier)...
The types of different units are in the config.cpp (there are the BIS released commented configs somewhere in the Ed Depot (probably)), or you can have them by using the command
typeOf...
You can have the typeOf shown in the screen with
hint format ["%1",typeOf unitname]
Either in scripts or triggers...
No guarantees on the syntaxes though