Classification of the coordinates of a set of points (the survey) produced by a single surveying project. It differs from the classification of control in that the set as a whole rather than the individual points in the set is classified. The practise is to place the survey in the same category as would have been placed a single control point considered characteristic of the points actually produced by the survey. The largest error produced by the survey may be used as a basis, or the average error, or some more complicated function of coordinates and their errors may be used.