Clock is ticking to 1st July 2016 when loaded containers can only be loaded on board ships after providing verified gross mass (VGM) to the carrier in advance as agreed meeting the regulatory norms of Verified Gross Mass as stipulated by the country of loading.
Below are some industry guidelines on Verified Gross Mass
U.K. Maritime and Coast Guard Agency
United States Coast Guard
World Shipping Council
European Chemical Industry Council + Freight Forwarding Trade Association