Development Modification Proposal 0337: Introduction of a Inter-day Linepack Product – OPEN LETTER Review Group 0291 11 August 2010 14th November 2010

Open Letter National Grid to raise an Open Letter seeking industry views on their anticipated usage and the viability of Linepack Product to Users. Open Letter consultation will be completed prior to commencing the Modification Proposal consultation period. Open Letter will facilitate final development of the Proposal and inform the User Pays option included in the Modification Proposal. Allows views of those unable to attend Workstream meetings to be captured prior to finalisation of the Modification Proposal.

Open Letter – Industry views sought on the following areas: expected utilisation of Service valuation of the service reserve pricing User Pays Options impact on other products (OTC Trading, OCM, Storage Services) Potential structure of any National Grid Inter-day Linepack release incentive any other comments

Open Letter – consultation timetable Final MP0337 Development Workstream meeting 14 Dec 10 Open Letter - for industry consultation 20 Dec 10 Issue Inter-day Linepack Methodology Paper 12 Jan 11 incorporate into MP0337 Open Letter – close out of representations 24 Jan 11 MP0337 Workstream report to Transmission Workstream Incorporating relevant feedback from Open Letter 3 Feb 11 Panel review MP0337 Workstream Report 17 Feb 11 MP0337 Workstream Report to Panel Include suggested legal text Include relevant feedback from Open Letter recommendation to consultation 17 Mar 11 FMR to April Panel 21 Apr 11 FMR issued to Ofgem for decision 22 Apr 11