"Aln" is a unit of length that is used in some parts of Scandinavia, particularly in Sweden and Norway. The term "aln" is derived from the Old Norse word "alinn," which means "forearm." Historically, it was a common unit of measurement for cloth, textiles, and land.
The exact length of an aln could vary by region, but it was generally around 2 Swedish feet or approximately 59.4 centimeters (or about 23.4 inches) in Sweden. In Norway, an aln was somewhat longer, typically around 62.7 centimeters (about 24.7 inches).
The use of the aln as a standard unit of measurement has largely been replaced by the metric system in Scandinavia and most parts of the world, but it may still be referenced in historical or traditional contexts.
In the United States surveying system, an "inch" is a unit of length, but it is not significantly different from the standard inch used in everyday measurements. An inch in U.S. surveying is equal to 1/12th of a foot, just like the standard inch. This means that one U.S. survey inch is approximately equal to 0.0833333 feet or about 2.54 centimeters.
The primary distinction in U.S. surveying is the use of the survey foot, which is defined as exactly 12 survey inches. This slight difference in the definition of the foot and inch in U.S. surveying is used for precise land measurements and surveying work, especially when dealing with large areas of land. However, for most everyday purposes, the standard inch and foot are used in the United States and other countries that employ the imperial system.