Art. 283 SchKG; landlord’s retention inventory and contractual extension of retention rights; scope of supervisory review. The Betreibungsbeamte and the supervisory authorities are not competent to decide on the validity of a contractual clause creating a retention right over objects excluded by law from landlord’s retention. Yet the inventory under Art. 283 SchKG may comprise only those objects over which the landlord has a retention right pursuant to Arts. 294, 295 and 297 OR. The extraordinary measure of provisional seizure cannot be extended by private agreement beyond the statutory circle of retentions; a broader contractual claim must be asserted in ordinary proceedings and, if necessary, judicially established.