Here an according section from the goldrush.script file:
[code]
tank_construct
{
    spawn
    {
        wait 1000

        kill tank

        constructible_class 2            // <-- tank can be destroyed by nades, mines etc.
        constructible_health 1200               // <-- health points for tank
        constructible_constructxpbonus 10    // <-- increased xp for repairing the 
tank
        constructible_destructxpbonus 10        // <-- increased xp for destroying 
the tank
    }

    built final
    {
        alertentity tank

        wm_announce "The Tank has been repaired!"
    }
}
[/code]