1. http://nodal.ercot.com 1 Market Trials Outage Scheduling Weekly Update August 13, 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 –CIM Load –Known Issues Standing Reports and Updates –General reminders / updates Outage Scheduler Transition to Go-Live 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 Day-to-day operations summary: Planned / Unplanned Outages of EDS Planned Outages –08/13/2010 8:00 A.M. – 08/16/2010 8:00 A.M. (Wait until confirmation Market Notice before updating outages) The following application services will be unavailable in support of cutover activities being planned for transition into dual entry mode: –OS –OS-UI –EWS ( Outage Scheduler components only) Unplanned Outages –N/A Network Model Load Dates –08/02/2010 –08/18/2010 –09/01/2010

6. http://nodal.ercot.com 6 General reminders / updates Reminder: Outage Scheduler with Zonal Outage Transfer Delete all Outages and run Zonal to Nodal Transfer Tool Friday, 8/13 (Note that 80% to 85% of the outages are transferred) Resource Outages will not be transferred by the Transfer tool The target is to make available for outage transfer validation and outage submissions Monday 8/16, 8:00 am, for the upcoming tests, optional months of October & November and for December and beyond A Market Notice will be sent out once ERCOT has completed this work. It is important that MPs do not start validation prior to receiving this Market Notice. Request list of Outages not transferred from MarketTrials@ERCOT.comMarketTrials@ERCOT.com Send email to Market MarketTrials@ERCOT.com confirming outages have been validated by 9/17 for all Outages December and beyondMarketTrials@ERCOT.com First production pull of OS data is scheduled for 10/2 for the first CRR Auction TSPs and QSEs are responsible to ensure that the outages in the Nodal Outage Scheduler are correct Outages previously approved in zonal will be automatically approved in Nodal

7. http://nodal.ercot.com 7 Environment Report: Known Issues Known issues posted to the readiness center at: http://nodal.ercot.com/readiness/markettrials/os/index.html http://nodal.ercot.com/readiness/markettrials/os/index.html Newly Opened Issues: StatusIssueDescriptionWork Around/Comments Open Related equipment only displays 100 rows, so lines over 100 are missing all rows over 100 If related equipment is selected for a Line or a transformer and there are more than 100 pieces of equipment, the OS will only display 100 of the pieces. The MP can pick the equipment from the drop downs to add them to the group outage. Open Custom Filter - Operating Company does not stay highlighted after the apply button is selected When the user uses the custom filter, the next time the filter is opened, the Operating Company is not selected. MP will select the Operating Company. Open When you delete a row from a group on create it it will clear the group name causing the user to have to re-enter group name before submitting The User will re-enter the group name before submitting.

8. http://nodal.ercot.com 8 Q&A Q&A / Open Forum