A hectad is an area 10 km x 10 km square. The term has a particular use in connection with the British

Ordnance Survey Ordnance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose (see ordnance and surveying), which was to map Scotland in the wake of the Jacobite rising of 1745. There was a ...

national grid, and then refers to any of the 100 such squares which make up a standard 100 km x 100 km myriad; these are denoted using the letter code of the 100 km square, and then a two-digit number consisting of the one-digit

easting A projected coordinate system, also known as a projected coordinate reference system, a planar coordinate system, or grid reference system, is a type of spatial reference system that represents locations on the Earth using cartesian coordina ...

of the western bound of the hectad and the one-digit

northing A projected coordinate system, also known as a projected coordinate reference system, a planar coordinate system, or grid reference system, is a type of spatial reference system that represents locations on the Earth using cartesian coordina ...

of its southern bound.

See also