Kernrechtsfrage
Whether the 9 March 2006 declaration constituted a valid suretyship securing a flat-rate underlying debt of CHF 50,000.
Extrahierter Entscheid
The declaration was a valid suretyship, and the underlying obligation was a flat-rate amount of CHF 50,000.
Extrahierte Begründung
The lower courts' assessment of the parties' agreement was not arbitrary. The project presentation, the wording of the guarantee, and subsequent conduct supported a flat-rate cost arrangement.