In Owusu v. Commonwealth, 11 Va. App. 671, 401 S.E.2d 431 (1991), the Court described the failure of locational proof as a failure to prove "subject matter jurisdiction." This failure of proof impaired the trial court's "subject matter jurisdiction" because it impaired the ability of the trial court to try the accusation before it. The essence of the impairment, however, went not to the true subject matter of the case, the classification of the issues on trial, but rather to proof that the events alleged occurred within the trial court's territorial jurisdiction.