Changes made by Council Directive 2013/22/EU of 13 May 2013 adapting certain directives in the field of transport policy, by reason of the accession of the Republic of Croatia
EU Directive 2013/22
Made to Council Directive 1999/37/EC of 29 April 1999 on the registration documents for vehicles
From legislation.gov.uk's record of changes, the official one: see it there.