Domesday is a variant of doomsday and alludes to the day of reckoning. In Norman times, William the Conqueror ordered that an economic survey or audit be carried out on the citizenry, essentially for taxation purposes. The data compiled included land ownership and usage details, neighbourhood customs and disputes and livestock numbers and it constitues a unique public historical record. It is still the first point of reference in genealogy research in England and is the oldest surviving government document. The volumes of the Domesday Book have been divided for preservation and are held at the National Archives in Kew.