Changes to Council Directive of 29 June 1990 concerning a Community procedure to improve the transparency of gas and electricity prices charged to industrial end-users (90/377/EEC)
EU Directive 1990/377
Made by Commission Decision of 7 June 2007 amending Council Directive 90/377/EEC with regard to the methodology to be applied for the collection of gas and electricity prices charged to industrial end-users (2007/394/EC)
From legislation.gov.uk's record of changes, the official one: see it there.