DIN 18202 (Deutsches Institut für Normung (DIN), the German standard)
The latest version of the DIN 18202 standard was published in April 1997. It concerns the flatness of various types of floors, especially for "free movement" floors (warehouses with wide aisles, transfer areas and bulk storage...).
With this standard the gap is surveyed under a straight edge of 1 meter and 4 meter. No transverse survey needs to be carried out.