The Tract
Six miles on each side of the Grand River.
From the river’s mouth at Lake Erie to its head. Press any point on the map to learn whether it is within the six miles, or ask the device where you are.
Press the map, or the button.The streets inside the Tract are shown clear. Move in close to find your own road. Your position is worked out on your own device and is sent nowhere.
The six-mile lineOutside the six miles, washed backThe point you pressed, or where you are
This is guidance. The formal answer is a Tract certificate from the Register, with its Record Code. The line is certified to within 2.1 metres; a point within a few metres of it should be checked on the ground.