Kernrechtsfrage
Whether ancillary charges were validly and specifically agreed to be borne by the tenant.
Extrahierter Entscheid
No valid special agreement specified which ancillary charges were owed by the tenant; monthly advance payments did not suffice.
Extrahierte Begründung
Under Art. 257a(2) CO ancillary charges are payable only if specially agreed and described clearly and precisely; the lease clause here named only a monthly advance and later settlement, without specifying the relevant charges.