Key legal question
How should the contested pension guarantee clause be legally qualified: surety, guarantee, or cumulative assumption of debt?
Extracted holding
The cantonal court's qualification cannot stand because the clause was interpreted without sufficiently considering the concrete contractual context; the case must be re-examined.
Extracted reasoning
Objective interpretation under Art. 18 CO requires the wording to be read together with the negotiations and circumstances. On the existing findings, it is not plausible that the buyers would have undertaken a classic surety for an obligation already regarded as due and solvent; the factual basis is incomplete.