The turn (symbol tr or pla) is a unit of plane angle measurement that is the measure of a complete angle—the angle subtended by a complete circle at its center. One turn is equal to radians, 360 degrees or 400 gradians. As an angular unit, one turn also corresponds to one cycle (symbol cyc or c)
Unit symbols
There are several unit symbols for the turn.
EU and Switzerland
The German standard DIN 1315 (March 1974) proposed the unit symbol "pla" (from Latin: 'full angle') for turns.
which also received other special names, such as the radian.