Nexus Workgroup Read Validation Scenarios 4th December 2013

Background Read Validation rules and tolerances developed during the Settlement BRD Concern raised at 30th October workgroup that the tolerances may not be appropriate for Class 4 sites as a ‘flat profile’ is used (AQ / 365 x no. of days in period). Workgroup agreed the principle of read validation was correct but would like to examine the tolerances further The following slides provide a list of various scenarios considered by Xoserve during analysis of the AQ requirements to validate the principles & tolerances described in the BRD

Scenarios AQ = 1 Reason: the site has not been consuming gas for over 9 months Consequence: read will fail validation Outcome: AQ Correction process used to re-calculate the AQ then re-submit the read AQ is significantly higher or lower than sites predicted consumption Reason: change in plant or site previously ‘mothballed’ Consequence: read may fail validation

Scenarios cont. Site Isolated Vacant site AQ would carry over until 9 months consumption was available during the non-isolated period therefore read would not fail Vacant site AQ would reduce as reads are loaded with zero/low consumption over a period If read fails due to the AQ being low, the AQ Correction process to be used to amend AQ Round The Clock value incorrect/not populated Read would fail due to out of tolerance Re-submit read with correct ‘Round the Clock’ (TTZ) count

Scenarios cont. Change of Class – Class 4 to 2 SOQ is used to validate the reads, Shipper nominates the SOQ Change of Class – Class 2 to 4 Daily reads previously loaded for site and AQ reviewed monthly. Reads should therefore pass the validations based on AQ