Here you will find the GitHub repo for maintaining the Met Office Local Table extensions to the WMO BUFR and GRIB codes (http://codes.wmo.int/). These can be found at the following webpage: http://reference.metoffice.gov.uk/grib/_grib2 once published.
If you would like to request a new addition to the Met Office local tables, please create a new issue using one of our templates. These include the 'GRIB2 Local codes request form' and the 'BUFR Local codes request form'. Please include as much detail as applicable and any additional information needed will be requested via the issue comments. We will check the request against our criteria and look to publish the terms as soon as the request has been approved.