Score one for D.C. sovereignty. Actually, make that 13: Earlier this summer, school-watchers were wondering why the entire automotive fleet of the District’s school police unit bore Maryland and Virginia tags. But as of last week, the 13 cruisers can be considered liberated. According to school system spokesperson Denise Tann, the cars have gone in for a makeover and will be outfitted with D.C. government plates. The fleet’s out-of-town designation was due to the fact that the contract for school security is held by MVM Inc., a McLean contractor which in turn gets its cars from Enterprise Rent-a-Car (“Chevy Suburbans,” City Desk, 7/2). An MVM official says that D.C. made no registration stipulation when it contracted out the service in 1996, adding that MVM is more than happy to slap on the D.C. government plates. They’re free, after all.