1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Qualifications Weekly Update March 26, 2010

2. http://nodal.ercot.com 2 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. DISCLAIMER All presentations and materials submitted by Market Participants or any other Entity to ERCOT staff for this meeting are received and posted with the acknowledgement that the information will be considered public in accordance with the ERCOT Websites Content Management Operating Procedure.

3. http://nodal.ercot.com 3 Agenda Anti-trust Admonition Environment Report –Planned / unplanned outages –Known Issues –CIM Load Standing Reports and Updates –General reminders / updates Qualification Update Question and Answers / General Discussion ERCOT asks that Market Participants log into the WebEx session using their company name and then their name. This will allow ERCOT to take roll-call offline

4. Market Trials 2010 Roadmap http://nodal.ercot.com 4

5. http://nodal.ercot.com 5 Environment Report: Planned / Unplanned Outages Planned Outages –No planned outages to report Unplanned Outages –No unplanned outages to report

6. http://nodal.ercot.com 6 Environment Report: Known Issues Reminder: ERCOT will post known issues every Friday to the readiness center at: http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html New Issues:

7. http://nodal.ercot.com 7 Environment Report: Known Issues Closed Issues:

8. http://nodal.ercot.com 8 Standing Reports and Updates: General reminders / updates In March and April, the following CIM load dates are targeted: –3/31/2010 (data as of 3/15) –4/14/2010 (data as of 3/31) –4/20/2010 (data as of 4/6) –4/26/2010 (data as of 4/12)

9. http://nodal.ercot.com 9 Standing reports and updates: General Reminders / Updates Phase 4 Kick-Off Call –Great attendance and questions! –All meeting materials can be found at: http://www.ercot.com/calendar/2010/03/20100325-MT http://www.ercot.com/calendar/2010/03/20100325-MT Phase 4 Kick Off call highlights: Supported days / hours for Market Trials Phase 4 –The Nodal Production environment is still considered a test environment, consequently it will be necessary to bring the environment down periodically to perform maintenance and patch releases to the software –The following details the supported days and hours ERCOT is actively monitoring the nodal production environment CRR, OS and External Web Services: Monday through Friday from 8:00 am to 6:00 pm MMS, SCED, EMS, Telemetry and MIS: 24x7 –Maintenance: For those systems that are not 24x7, they will remain accessible outside of the support windows that are, however there is no guarantee of system stability or accessibility outside of the supported windows For those items that are supported 24x7, ERCOT will communicate to the market via a market notice when maintenance or planned outages will take place

10. http://nodal.ercot.com 10 Standing reports and updates: General Reminders / Updates Phase 4 Kick Off call highlights (continued): During phase 4.0, ERCOT will use an automated load process that pulls zonal outages into the nodal outage scheduler This process is successful for about 85% of the zonal outages

11. http://nodal.ercot.com 11 Standing reports and updates: General Reminders / Updates Phase 5 Handbooks to be published on 3/31/2010 –Outage Scheduler covering Phase 5.0 will be published to: http://nodal.ercot.com/readiness/markettrials/os/index.htmlhttp://nodal.ercot.com/readiness/markettrials/os/index.html

12. Qualification Update 63 / 85 QSEs are qualified (no change) 14 / 25 TSPs qualified (up from 2) 3 Business days left to complete Outage Scheduler Qualification The Outage Scheduler Qualification Dashboard –The dashboard will be updated ever Friday at 7pm http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com 12

13. http://nodal.ercot.com 13 Q&A Q&A / Open Forum

14. Appendix http://nodal.ercot.com 14

15. http://nodal.ercot.com 15 Environment Report: Changes to Supported Environment Hours Outage Scheduler Environment Availability for February - March 2010 –The Nodal Production Environment will be available Monday – Friday from 8am – 6pm –Outside of these hours, ERCOT will be executing performance testing and patch migrations based on testing results –For those MPs that provided ERCOT test certificates, there will be test notifications sent to your listeners (where applicable) during these internal ERCOT tests –ERCOT will coordinate with MPs when submitting to avoid qualification transactions Please note that only functionality that pertains to the Outage Scheduler qualification activities has been validated and are supported –Other features (such as reports and other MIS functionality) may be present in the environment but may have issues –ERCOT is still in the process of validating features to be released in later Market Trials Phases