I think this is only useful in mission tracks.
If the race type in Races.txt is 4 or 5 (Smash / Smash and peds), this can be used to define what are the mission targets:
(In other words: what smashables increase your " destroyed targets"-number)
1 // Number of run time variable changes
1,1 // Don't know much of these, but write 1,1 anyway.