in the general case, the main area of a given parcel of a survey unit is where the parcel has only one occupation during a crop year, unequivocally defined by that occupation (In this case the secondary area of that parcel will be zero.)
If the parcel of arable land is used more than once during a given crop year (successive cropping), and the area each time has only one crop, then the main area is the crop with the highest value. If the value of the production does not determine which is the main crop, then the main crop is taken as the one which occupies the ground for the longest period of time. Secondary area: All other occupations are then regarded as secondary areas.
