is a two by two kilometre square. Previously they were the basis for most recording, now this is a monadis a one kilometre square on an ordinance survey map.. There are 25 tetradsis a two by two kilometre square. Previously they were the b… within a hectadthe is a 10 x 10 km square on an ordinance survey map contai… and they are labelled with the hectadthe is a 10 x 10 km square on an ordinance survey map contai… number and a letter. The letter O is not used to avoid confusion. This diagram shows which monadis a one kilometre square on an ordinance survey map. is in which tetradis a two by two kilometre square. Previously they were the b….
