1. Lead from the front Texas Nodal http://nodal.ercot.com 1 EDS 3 Release 5 and 6 Friday Market Updates Oct 24, 2008

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 Agenda Antitrust Admonition Roll Call SCED Update –Submission Metrics Update –Updates / Questions / Reminders LFC / State Estimator Update Q&A / Open Forum API Subgroup Topics (General Discussion Only)

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 Submission Metrics Update 10/18/200810/19/200810/20/200810/21/2008 N/A88%34N/A87%33N/A88%3484%89%39 COP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOS Submit the following for each trade date: –Three Part Offer or Output Schedule EOC only required. Should cover 80 – 120% of cost Min Energy / Start-up may be zero’d out FIP/FOP must sum to 100% –COP Only required if submitting an Output Schedule No updates in the adjustment period required Note: a COP is also required in order to submit during the adjustment period (this will be changed to a warning in the next release of MMS  MMS4) 10/22/200810/23/200810/24/2008 76%85%3985%92%42N/A78%32 COP TPO IDOOSCOP TPO IDOOSCOP TPO IDOOS Blue Background = Focused Input Windows State Estimator / SCED Next Focused Input starts 11/4 Start submitting COP’s 10/28

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Updates / Questions / Reminders Unplanned Environment Outages –No Outages to Report REMINDER: Planned EDS Environment Outage –Outage Spans from 10/24/08 5pm – 10/27/08 8am –This will effect all MMS and Outage Scheduler interfaces –Basepoints / LMPs over ICCP will remain static –Market Participants will not be required to make submissions for Trade Dates: 10/25 (SAT), 10/26 (SUN) and 10/27 (MON) All normal submissions should be in place for 10/28 (Tues) REMINDER: Send to eds3@ercot.com the Certificate Authority your MP is using or intends to useeds3@ercot.com

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Updates / Questions / Reminders REMINDER: External Interfaces Specification v1.17 –Posted to the Readiness Center at: http://nodal.ercot.com/readiness/sandbox/documents/index.html http://nodal.ercot.com/readiness/sandbox/documents/index.html –Send all comments to eds3@ercot.comeds3@ercot.com Daylight Savings Time 11/02 –ERCOT will not perform any formal testing during this period –The MMS version in EDS does not fully support the final implementation of DST –What may work now may behave differently in the future –Formal DST testing will be communicated with the release of the Nodal Integrated Schedule

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 Updates / Questions / Reminders Updated Intermediate Certificates and Extended Inventory of Certificate Authorities (CA’s) –Both of these issues will be resolved in a release on 11/11/08 All renewed Intermediate certificates will be supported All CA’s sent to eds3@ercot.com by 10/31 will also be supportededs3@ercot.com –An upcoming market notice will detail the specifics of the outage

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 Focused SE & System Constrained Economic Dispatch Testing (SCED) FIT II Assessment reports will be posted at: http://nodal.ercot.com/readiness/eds3/documents/index.htmlhttp://nodal.ercot.com/readiness/eds3/documents/index.html Observations –TPO & OS submissions missing (12-15% fewer) –Lack of TPO & OS may affect LMP’s –Telemetry Issues

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 Focused SE & System Constrained Economic Dispatch Testing (SCED) Observations –Convergence % Decline since FIT I –97% Convergence will require full market support to achieve

10. Lead from the front Texas Nodal http://nodal.ercot.com 10 Q&A Q&A / Open Forum

11. Lead from the front Texas Nodal http://nodal.ercot.com 11 API Sub-Group Topics General Discussion