 The courts often use a more concrete approach to calculate damages in contractual cases, comparing the value that the specific asset or obligation would have had with its actual value after the breach (rather than on the patrimony as a whole).In terms of the market-value approach (where performance consists of marketable goods), the amount of damages is determined by the difference in the market value of the goods as received and the market value they would have had if the goods had conformed with the requirements of the contract.In terms of the once-and-for-all-rule, the plaintiff must claim all of his damages in one action.