1. Lead from the front Texas Nodal http://nodal.ercot.com 1 Early Delivery System Testing Environments & Planning – Involving Market Participants TPTF May 8, 2007

2. Lead from the front Texas Nodal http://nodal.ercot.com 2 Objectives for today’s presentation Address EDS 3 Plan document comments Get acceptance of the EDS Timeline plan as a baseline Get agreement on additional MP involvement and the concept of the MP Handbook

3. Lead from the front Texas Nodal http://nodal.ercot.com 3 Market Trials Approach No Longer Valid This document was presented to TPTF twice in November 2006 Not approved due to insufficient detail Document contained approaches and dates no longer valid This document has been archived on the Nodal site, please disregard and do not use as a reference

4. Lead from the front Texas Nodal http://nodal.ercot.com 4 Response Approach & Main Comment Categories Comments responded to were included in the document and the necessary responses included in the spreadsheet Comment categoryAction Timeline – July vs. October What is mandatory? A table was added to Section 1.4 of the document clearly explaining each phase as defined by ERCOT Further detail required Testing process Data inputs and outputs Entry & exit criteria MP Readiness activities and timing Further detail added where available. The remaining detail will be gathered at the EDS Planning Workshops ERCOT will compile draft white papers –SCED details and gaps will be addressed and the document finalized from the EDS Planning Workshop with MPs Present to TPTF for approval Market Participant Handbook clarification Explanation of MP Handbook added to Section 1.5 This document will be further explained and refined to at the workshop Suggestions for content Joint planning workshops General punctuation Insertion of content/clarity Document updated accordingly. Registration & qualification activitiesThese activities are covered in the relevant Registration /Qualification documents. An explanation to be added to the introduction in this document for clarity Request for joint planning workshops going forward A section added to the document explaining the proposed workshops. First workshop scheduled for May 24 th to discuss SCED testing

5. Lead from the front Texas Nodal http://nodal.ercot.com 5 Summary of pending issues and plan of action Comment categoryAction Methodology for submitting offers ERCOT will compile a draft white paper - any details and gaps will be addressed at the first EDS Planning Workshop with MPs on May 24 th SCED input data questions SCED SMEs will be available at the first EDS Planning Workshop on May 24 th to address issues Interface criteria for SCEDWeb Services developers will be available at the first EDS Planning Workshop on May 24 th to address issues LFC testing issuesEDS Planning Workshop to be scheduled to define solutions with ERCOT SMEs and MPs All comments in the pending category related to the requirement for further detail and were classified as pending. These areas will be explored during ongoing planning forums.

6. Lead from the front Texas Nodal http://nodal.ercot.com 6 Planning & MP Involvement Approach

7. Lead from the front Texas Nodal http://nodal.ercot.com 7 Ongoing EDS Planning Process Planning Phase or Artifact EDS ApproachEDS PlanMP Planning Workshops and WebEX Meetings MP HandbookPre EDS Test Scripts ContentDocument defining the phases and artifacts from ERCOT for EDS planning and execution Detailed plan defining sufficient detail for MPs to begin planning system functionality and implementation sequence Detailed planning sessions to build consensus on data, test cycles, test scenarios, entry and exit criteria Consolidated agreed content from MP workshops Calendar, test cycles, contact information, data requirements, test scenarios & scripts etc Detailed scenarios and data input requirements for two weeks of testing. To be provided in rolling two week intervals. Timing D = EDS Start Date November 2006D – 6 MonthsD – 3 to D – 1 Month D – 2 weeks FrequencyOnce Weekly to Monthly by MP type Complete prior to EDS start. Calendar / Data updates during execution. Initial release prior to EDS start. Updates & additions during execution. Output Medium MS Word posted on Nodal.ercot.com TPTF Purpose Informational Approval

8. Lead from the front Texas Nodal http://nodal.ercot.com 8 Participation in the EDS 3 Testing Phases (Section 1.4 – EDS 3 Plan) Market Participant TypeActivitiesTimeframeExpectation QSEs with resources planning on utilizing API’s in production MP Development Connectivity Testing (Sandbox) July - SeptemberStrongly Recommended MP Connectivity Testing (EDS Environment)July - SeptemberStrongly Recommended MP Connectivity Testing (EDS Environment)OctoberMandatory * MP Input Validation – SCEDAug – SeptemberStrongly Recommended MP Input Validation – SCEDOctoberMandatory * MP Input using SCED User InterfaceOctoberRecommended ** All QSEs with resources MP Input using SCED User InterfaceJuly – SeptemberRecommended ** MP Input for SCED ExecutionOctober – DecemberMandatory for designated EDS testing days MP Input for 6 month LMP PeriodJanuary – June 2008Mandatory based on define scenarios and methodology QSEs with resources not planning on utilizing API’s in production MP Input using SCED User InterfaceOctoberMandatory * * Starting in October Market Participant involvement is critical to begin producing “Reasonable” LMPs. During this period the Market Participants should have a partial EDS system in place to support the activities and functionality being demonstrated. The EDS team will provide workshops during this time to support Market Participants. Required Market Participants that are not able to participate will have to still perform these activities by requesting a ‘make-up’ workshop prior to involvement in later EDS activities. There will be limited opportunities for support due to focus on other EDS functionality. ** The EDS team recommends that all QSEs with resources schedule some time to get familiar with the SCED user interface even if they are planning on utilizing APIs in production. This will help ensure that Market Participants have a second method for accessing the EDS systems if their APIs are not functioning correctly.

9. Lead from the front Texas Nodal http://nodal.ercot.com 9 The Nodal timeline contains early EDS phases to ensure ERCOT & MP readiness … Early Start