Lead from the front Texas Nodal 1 EDS 3 Release 5 Phase 1 Testing Monday / Friday Market Updates September 26, 2007

Lead from the front Texas Nodal 2 Agenda Antitrust Admonition Roll Call Review of Testing Schedule Updates –Sandbox Release –October / November Expectations and Activities –Reminders –Follow-up to Data Dictionary Q&A / Open Forum

Lead from the front Texas Nodal 3 Antitrust Admonition ANTITRUST ADMONITION ERCOT strictly prohibits Market Participants and their employees who are participating in ERCOT activities from using their participation in ERCOT activities as a forum for engaging in practices or communications that violate the antitrust laws. The ERCOT Board has approved guidelines for members of ERCOT Committees, Subcommittees and Working Groups to be reviewed and followed by each Market Participant attending ERCOT meetings. If you have not received a copy of these Guidelines, copies are available at the Client Relations desk. Please remember your ongoing obligation to comply with all applicable laws, including the antitrust laws.

Lead from the front Texas Nodal Week Outlook Tests Scheduled for week beginning 10/01 –Support / Testing Call STEC 10/01 **MILESTONE – EDS 3 Phase 1 Complete Week Beginning 10/08 EDS Environment Down for Maintenance and Upgrade

Lead from the front Texas Nodal 5 Review of Testing Schedule : Week’s Status Report Note: numbers and percentages include sub-QSE’s

Lead from the front Texas Nodal 6 Updates Sandbox Release –Sandbox Update Completed – Resolved issues introduced last week Published new XSD’s WSDL’s for Sandbox –Notifications updated to current EDS release Still working on one outstanding issue before Notifications are restored to sandbox ETA on resolving issue EOB 9/29/07 October / November Expectations and Activities –QSE’s to receive resource data 10/5/2007 (updated delivery date) –Submit SCED inputs via web services for your entire portfolio (mid-Oct) –Ensure your Nodal ICCP feed is operational (Now) Start providing new ‘Nodal ICCP’ points –Local ICCP failover test (Now) –Validate Resource specific Base Points and LMPs (Nov ‘07) –Use Nodal Sandbox for next set of web services (Now) Reminders –LFC Workshop – Oct 10th, am – 4pm Taylor Office – Room 253 and WebEx MP Technical / Operations personnel highly encouraged to participate Agenda: –Overview –Testing Process - Technical discussion with MP operational personnel –Settlements Discussion

Lead from the front Texas Nodal 7 Updates Defect Fixes to be released during EDS outage week to be published next week Work around requiring HH:59:59 on ending time values will be released late October. –This will require MP’s to use the hour ending –This will be released with the next push to MMS Version 1.04 of the Machine to Machine Interface Specification –Sandbox will be updated to 1.04 at the end of October –EDS will be updated to 1.04 at the end of November

Lead from the front Texas Nodal 8 Data Dictionary 1.Feedback received: ―Content: Entity – e.g. names, descriptions, rules, etc Attribute – e.g. data types, lengths, precision, etc ―Usage: Align output with Use Cases (already in progress) ―Formats: Word/ Excel (we will also look at xml) ―Timeline: Align to EDS and Release 1 st cut – potentially start of November (EDS 2 Release 3) Play catch up 2.Next Steps: over coming week: ―Opportunity for further feedback/ input ―Provide sample data dictionary towards end of next week

Lead from the front Texas Nodal 9 Q&A Q&A / Open Forum