It consists of 400 stainless steel poles with solid, pointed tips, arranged in a rectangular 1 mile x 1 kilometre grid array.

In contrast, in much of southern Ontario the basic survey grid was based on a mile-and-a-quarter (1.25 mi), which corresponds almost exactly to a 2 kilometre grid and which makes miles no more natural than kilometres.

Although these areal units will alter less with time than administrative units, they are nonetheless transitory and so, ideally, smaller and more permanent units like kilometre grid squares should be used, as they have been by the OPCS in a limited fashion, as the basic building block.