An object lesson on how a fastidious lawyer — yea, even a historical succession of them, from the dawn of antiquity — can make a mountain out of a molehill.

A business day, we all know, is a day when someone will be in the office: not a weekend, not a public holiday - but don't let that stop your advocate doing his best to complicate that by reference to commercial banks, the settlement of foreign exchange, securities markets, the principal financial centre, local business days, delivery days, settlement days - you name it.

Each year, bankers, lawyers and like-minded pedants gather in Las Vegas to discuss the minutiae of these definitions before repairing to the bar to network and drink themselves into a stupor at the annual international business day convention.

The many gorgeous, multi-hued variations on the business day can be enjoyed as follows:

ISDA extended universe