Template:M summ Equity Derivatives 12.8(d)
If, having gone out and got some dealer quotations or market data for the purpose of determining the Cancellation Amount, the Calculation Agent doesn’t like what it got, it has to use it unless with a straight face it can say to do so would be to produce some manifestly erroneous outcome. This keeps the Calculation Agent — which will be one of the parties, remember; usually the dealer — honest (if its regulatory obligations to treat customers fairly, not be a dork and so on, doesn’t).