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.