With bondholders facing a 50% haircut following the latest arrangement sealed in Brussels, it would be fair to assume that the word "default" may be whispered in the credit default swaps market. So here is a useful guide about who – and what – decides when enough is enough.

A refrain oft-repeated by eurozone officials negotiating a writedown in Greek debt was that they had to avoid a payout on credit default swaps - a form of insurance that is triggered when a so-called "credit event" occurs.