Before starting earthworks in a given area, it is necessary to properly mark the area of ​​future excavations and embankments, designation of characteristic points and specification of the designed ordinates. Characteristic places are marked by placing stakes that define the situation, design height, etc.. If the stake marks a point at the bottom of the trench or provides other important field markings, then another called the witness is placed next to him, usually with a sufficiently smooth surface, on which the necessary markings are given (ordinates, distances, slopes etc.). Due to the required visibility of all markings in the field, they are painted white. The designations relating to the works may be changed along with the progress of the works.