|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
A circular mil is a unit of area, equal to the area of a circle with a diameter of one mil (one thousandth of an inch). It corresponds to 5.067×10−4 mm². It is a unit intended for referring to the area of a wire with a circular cross section. As the area in circular mils can be calculated without reference to π, the unit makes conversion between cross section and diameter of a wire considerably easier.
Survey township, sometimes called Congressional township, as used by the United States Public Land Survey System, refers to a square unit of land, that is nominally six (U.S. Survey) miles (~9.7 km) on a side. Each 36-square-mile (~93 km2) township is divided into 36 one-square-mile (~2.6 km2) sections, that can be further subdivided for sale, and each section covers a nominal 640 acres (2.6 km2).