1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Qualifications Weekly Update March 19, 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 Webservices 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 –Weekend Upgrade: Fri 03/19/10 6pm – Mon 03/22/10 8am Maintenance activities are planned during the period in preparation for Market Trials phase 4. The outage will affect availability of: –Outage Scheduler –OS RUI –MIS –External Web Services –Outbound Notifications will be unavailable Tuesday Monday March 22, 6pm to Tuesday, March 23, 6pm OS Submissions still supported, but no notifications back Unplanned Outages –None this past week

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 No new issues Resolved issues on next slide

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

8. http://nodal.ercot.com 8 Standing Reports and Updates: General reminders / updates Network Model Update –Next scheduled load is 3/31/2010 Reminder of market call schedule: 09:00 AM-10:00 AM Outage Scheduling 10:00 AM-11:00 AM Congestion Revenue Rights 11:00 AM-12:00 PM Day Ahead Market / RUC / SASM 12:00 PM-01:00 PM Break 01:00 PM-02:00 PM Real Time Market / LFC –WebEx Details will be posted at: http://www.ercot.com/committees/nodal/mt/ http://www.ercot.com/committees/nodal/mt/

9. http://nodal.ercot.com 9 Standing reports and updates: General Reminders / Updates Reminder of Phase 4 Kick-Off Call next Thursday –Thursday, March 25 9am-3pm, Austin Airport Hilton –http://www.ercot.com/calendar/2010/03/20100325-MThttp://www.ercot.com/calendar/2010/03/20100325-MT –WebEx available Reminder of published the Market Trials Phase 4 Handbooks –Outage Scheduler covering Phase 4.0 http://nodal.ercot.com/readiness/markettrials/os/index.htmlhttp://nodal.ercot.com/readiness/markettrials/os/index.html –Real Time Market / LFC covering Phase 4.0 http://nodal.ercot.com/readiness/markettrials/rtm/index.htmlhttp://nodal.ercot.com/readiness/markettrials/rtm/index.html –CRR covering release Phase 4.0 http://nodal.ercot.com/readiness/markettrials/crr/index.htmlhttp://nodal.ercot.com/readiness/markettrials/crr/index.html –Settlements / COMs covering Phase 4.0 http://nodal.ercot.com/readiness/markettrials/coms/index.htmlhttp://nodal.ercot.com/readiness/markettrials/coms/index.html –Day-Ahead Market Phase 4.0 http://nodal.ercot.com/readiness/markettrials/dam/index.htmlhttp://nodal.ercot.com/readiness/markettrials/dam/index.html

10. Qualification Update 63 / 86 QSEs are qualified (up from 49) 12 / 25 TSPs qualified (up from 7) 9 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 10

11. MP20 Outage Scheduler Connectivity Qualification Nodal Scorecard Reminder for Metric MP20  Scorecard Calls – Starting 3/29/2010 ERCOT Account Managers will be notifying QSEs with Resources and TSPs of their scorecard status if qualification is not complete.  Scorecard Post Date – OS qualification window closes on 4/1/2010. AMBER/RED scores will post on 4/7/2010  Red, Amber, Green Rules  Red - Submissions not complete, participation not adequate  Amber - Incomplete Submissions, but actively working with ERCOT  Green - Submissions complete

12. http://nodal.ercot.com 12 Web Services Update Will be posted early next week Next NPROD release – Phase 5 Scope (these items previously announced as future changes): Change- Ancillary Service values –Change from “Float” to “Decimal” values to avoid scientific notation (eg, 1.6E01) Change - Cancel Outage API with ability to include notes –The existing “cancel OutageSet” API will be extended to allow the market participant to include RequestorNotes, SupportingNotes, and RASPSNotes in the request Payload. These elements will not be required. –The API will still support “cancel OutageSet” without notes. –The Market Manager UI will also support with and without notes. New - Get Notifications API –This will be a new API available to the market but not required for consumption. It will provide a market participant with the ability to query for Bid, Resource Parameter, and VDI acceptance and rejection notifications. –The API will support such features as querying by MRID, by time range, and by status (acceptance / rejection). The API will be constrained to a minimal amount of historical data availability. –The API / feature set will be available via the machine-to-machine API and Market Manager UI. Change - Startup / Shutdown Instructions Schema –Today, the hour ending is defined as an integer. This must be changed to string to allow the API to better represent DST (repeating hours using the * convention found elsewhere in the API for DST). EIS Specifications 1.19k

13. http://nodal.ercot.com 13 Web Services Update Scope (new): Confirmed/Unconfirmed Trades –Update example for mRID structure Opportunity Outages –Add new element takeOpportunity to OutageUpdate Dynamic Ratings API –Change deliveryTime to deliveryDate Three Part Offer –Clarify that curveStyle is not a valid element EIS Specifications 1.19k

14. http://nodal.ercot.com 14 Q&A Q&A / Open Forum

15. Appendix http://nodal.ercot.com 15

16. http://nodal.ercot.com 16 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