And the district court was not authorized to modify the decree sua sponte. See Martin v. Martin, 261 Neb. 125, 621 N.W.2d 511 (2001) (Neb. Rev. Stat. § 42-351 (Reissue 2016) does not authorize district court to modify, sua sponte, final order from which no appeal has been taken).
A jurisdictional question which does not involve a factual dispute is determined by an appellate court as a matter of law, in which case the appellate court must reach a conclusion independent from the lower court's decision. Martin v. Martin, 261 Neb. 125, 621 N.W.2d 511 (2001). ANALYSIS