Forest areas to be harvested are marked before the start of work. Earlier, each tree in the stand was marked individually either to be harvested or to be saved. Nowadays, stands are marked in the forestry maps, and the ”marking” is one of the tasks of the harvester operator, in that he or she decides which trees are cut and which saved. The most modern method of defining a stand for harvesting is to walk its boundaries in the terrain with a GPS device, which transmits the information into a GIS system. This is an electronic map containing a wealth of information, some of which may be transmitted electronically to a map shown on the harvester’s VDU. The same method is used to indicate areas to be avoided, such as natural sites to be spared.