Finnish Uniform Coordinate System

The Finnish Uniform Coordinate System (in Finnish Yhtenäiskoordinaatisto, YKJ) has been used in biological observation mapping since the 1970s. Based on YKJ, Finland is divided in square-shaped areas, the size of which are determined according to the needs of the study. The area division used in national biomonitoring is 10 km x 10 km squares, but in some cases 1 km x 1 km and 100 m x 100 m YKJ squares are also used. This data set includes XY-lines that form square grid in four scales according to Unified Coordinate System (100 m - 100 km), with identifiers describing each square.