1. Lead from the front Texas Nodal http://nodal.ercot.com 1 EDS 3 Release 5 Monday / Friday Market Updates November 30, 2007

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 Agenda Antitrust Admonition Roll Call Submissions Update –Submissions Status –Submission Window for Week of 12/03/07 Updates / Questions / Reminders Q&A / Open Forum

3. Lead from the front Texas Nodal http://nodal.ercot.com 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.

4. Lead from the front Texas Nodal http://nodal.ercot.com 4 Submissions Status Submissions Dropped Off During Holiday Weekend Submissions for trade dates 12/24/07 – 01/02/08 will Not be Tracked –During this period, submissions are not required, but optional –Please ensure that all submission requirements resume for trade date 01/03/07. Currently at our Highest Submission Rate (95%) –Please review notifications for errors on submissions –Reminder: Notification Listener is an Exit Criteria for EDS 3.5.3 11/20/200711/21/200711/22/200711/23/200711/24/200711/25/200711/26/200711/27/200711/28/2007 83%84%91%95%72%80%78% 76%79%84%76%88%80%89%94%95% COPTPOCOPTPOCOPTPOCOPTPOCOPTPOCOPTPOCOPTPOCOPTPOCOPTPO

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Submission Window for Week of 12/03/07 Activities for Week of 12/03/07 –Submit the following during the 12:00 – 4:00pm submission window: COP for next trade date TPO for next trade date Output Schedule (DSR resources only) INC/DEC (DSR resources only) –Submit RT COP adjustments during business hours –Submit RT OS adjustments during business hours (DSR only) –MP Offer Curve testing: Submitted during allocated 2 hour time slot only View schedule of time slots here: http://nodal.ercot.com/readiness/eds3/documents/r5/mp_offer_curve_testing.xls

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Updates / Questions / Reminders EDS Migration of External Specification V 1.04 Completed Successfully on 11/29/07 –Issues Found and under Investigation: Notification (async) header noun was set to “Notification” –Corrected back to “BidSet” in an release 11/29 Query by date (e.g. COP) not returning the full mrID –Under investigation with development Output Schedule’s mapping of 5 minute intervals is failing. –Output Schedules using 5 minute increments will fail on the last interval of each hour (00:55:00, 01:55:00, 02:55:00, etc) –Under investigation with development –Common MP Issue: GMT offset is now validated. Offsets not set at -06:00 will return an error. MIS Updates: –Pricing Reports will now publish automatically in line with their posting frequency requirements –Pricing Reports will roll off after 7 days to preserve performance LMP’s Over ICCP Issue –Link between SCED and EMS failed last week resulting in no dynamic LMP and Basepoints from ERCOT –ERCOT is developing a manual monitoring methodology until an automated one is put in place Question from Last Week: Can there be more detail (e.g. specific dates, milestones) around the high level Nodal Schedule and go live activities? –ERCOT will present at TPTF specific milestone dates leading up to go live –Discussion will begin at 10:30AM –Dial-In information can be located at the ERCOT website calendar of meetings under TPTF http://www.ercot.com/committees/board/tac/tptf/index.html http://www.ercot.com/committees/board/tac/tptf/index.html

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 Updates / Questions / Reminders Output Schedules –DSR Resources to begin submitting OS’s for trade date 12/3/07 –Known issues: Output Schedule performance issues may drop intervals causing an error with missing EOC –This occurs most frequently when submitting each 5 minute interval –Work around: Submit TPO in advance of OS and set to TRUE in OS. –Work around: Submit OS for full 24 hour block for each resource. Example: 2007-12-04T00:00:00-06:00 2007-12-05T00:00:00-06:00 123456 RESOURCE_NAME 2007-12-04T00:00:00-06:00 2007-12-05T00:00:00-06:00 2007-12-04T00:00:00-06:00 2007-12-05T00:00:00-06:00 150.0 Partial OS submissions (not a full 24 hours) require EOC in place for interval gaps –Work around: Submit TPO in advance of OS and set to TRUE in OS.

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 Updates / Questions / Reminders INC / DEC –Question from Monday’s Call: What is the INC/DEC format to be submitted starting 12/03? –Currently TPTF is reviewing a change in the Explanation of Market Submission Items document regarding INC/DEC curves. The change will not be included in the upcoming MMS Jan. ‘08 release Vendor will need to perform an analysis and estimate for release to ERCOT The current implementation of INC/DEC is consistent with how we tested in Phase 1 of EDS 3 (e.g. the first breakpoint of offer curve must be 0) For details on the current and proposed change, please refer to the latest TPTF review of the Explanation of Market Submission Items at : http://www.ercot.com/calendar/2007/11/20071126-TPTF.html Refer to document 21a1- MMS Explanation of Market Submission Items v0.25 under the Key Documents section. http://www.ercot.com/calendar/2007/11/20071126-TPTF.html21a1- MMS Explanation of Market Submission Items v0.25

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 Updates / Questions / Reminders ERCOT MMS Data / RARF Synchronization –ERCOT received the latest RARF’s on 11/09/07 –This data is in the final stages of review –>370 resources have updated Reasonability Limits –ERCOT will load these new limits into MMS on 12/06/07 @ 10am –On the day of the update: QSE’s will either: –Need to review notifications for error messages to retrieve the correct data –Contact the Resource Owner to obtain a copy of the latest RARF QSE’s will begin submitting all next day and RT transactions reflecting the new data –COP – Sustainable Limits –TPO – Re-adjust EOC –INC/DEC – Re-adjust EOC Send new adjusted TPO Cost Curve (spreadsheet) to eds3@ercot.com

10. Lead from the front Texas Nodal http://nodal.ercot.com 10 Updates / Questions / Reminders ERCOT MMS Data / RARF Synchronization (cont…) –Not all resources will be updated next week There are several RARF’s that still need correction QSE’s scheduling these resources will be notified with a new migration date

11. Lead from the front Texas Nodal http://nodal.ercot.com 11 Q&A Q&A / Open Forum