APX is pleased to present the current and future activities of the CAISO Market Redesign and Technology Upgrade (MRTU). This issue includes:

• MRTU Schedule
• Market Simulation
• APX MarketSuite™ Training
• CAISO MRTU Training

The CAISO announced at their March 26 Board of Governors meeting that the MRTU go live date will be Fall 2008. While they have yet to set a specific date, they concurred with the sentiment of the market participants that there was no realistic opportunity to implement the market changes prior to Summer, and that the additional time will better assure that software is stable and thoroughly tested by both the CAISO and Market Participants.

A specific go-live date is expected to be decided and announced in July. By July, the CAISO and Market Participants will have completed significant market simulation testing and will have had the opportunity to assess the stability and functionality of MRTU systems. The high level plan published by the CAISO acknowledges Market Participants request to have three months of stable access to the various systems between the conclusion of the current market simulation and go-live. Barring any severe software or system problems in the near term, there likely will not be any update on the go-live date from the CAISO until July.

Integrated Market Simulation Update 2 (IMS U2) restarted Monday, April 07, 2008. The CAISO used the break to repair known software defects and promote near final (go-live ready) functionality that has been under develop and testing by CAISO vendors. The first two weeks of testing met the success criteria established by the CAISO and Market Participants without any significant variances. The simulation is currently in a semi-structured phase with the CAISO once again hosting a group of market participants on-site. The onsite testing is proving to be valuable by providing immediate feedback when variances are encountered which accelerates the fix and re-test process.

The first two weeks of the market simulation resumption were highly structured. A static data set of system conditions and bids were used to determine if the system was stable and performance was adequate to begin more rigorous testing. To date, there have been few issues that prevented the CAISO and market participants from meeting the criteria set for this stage of testing. The Day Ahead market has run and published successfully each day and the real-time market runs have been completed successfully over 90 percent of the time.

Beginning Monday, April 21, semi structured simulation began and the simulation environment was opened for Market Participants to enter schedule and bid data that more closely resembles their actual business practices. To date, this phase of the simulation has run successfully producing Day Ahead results within the expected timeframe and continuing to run the real-time market successfully as well. Additionally the elements of the near final functionality that was updated during the break, to the extent they have been exercised, are working as well.

After demonstrating that the systems and processes can handle the variety of submitted bids by Market Participants, there will be a phase in which over 50 scenarios designed to emulate extreme and anomalous system and market conditions are run. The purpose of this phase is to demonstrate that the system is designed to perform under stressed conditions. It is expected that the scenario testing will run until July.

If you have any questions regarding details of market simulation or the next steps, please contact Spence Gerber at sgerber@apx.com or (916) 351-9759

As our commitment to our clients, APX continues to test the features and functionality of the MRTU APX MarketSuite™. The CAISO systems are now stable enough and, as the limitation of using CAISO created bids and schedules are being relaxed, Clients can interact with the market in a more meaningful manner through the APX MarketSuite beginning May 5th.

On a daily basis, APX clients will be able to enter schedules, bids and trades interactively against the simulation environment and see results and view settlement statements and reports through the APX MarketSuite™. This will also provide the opportunity for clients that want to see the varying impacts of the MRTU scenario testing on their resources to participate directly. This period also provides the opportunity to exercise any "what if" scenarios that clients are concerned about in the MRTU market environment.

If you are interested in participating in this phase of simulation, please contact Cris Gallegos (408.517.2154) or Spence Gerber (916.351.9759) to register.

APX will be conducting a client webcast demonstrating the features of the APX MarketSuite™ during the week of May 5th. Topics covered will include entry of bids and trades, reviewing bid status and market results as well as viewing settlement data. Information regarding the exact date and time of the webcast will be distributed the week of April 28.

For More Information, contact your account manager Cris Gallegos (408.517.2154)

The CAISO is continuing to provide webcast training for situations and functions that are new to the market under MRTU as well as refresher courses. To make the training more user friendly, the courses are two hours in length and offer multiple times with one of the sessions with a CAISO onsite option.

This months offering is scheduling requirements and impacts of Resource Adequacy resources under MRTU. The course is being offered on April 21, 24 and 29. These refresher courses will continue each month, and although a precise calendar has not yet been released, once the course content and dates are determined they are posted to the CAISO calendar.

Contact your Account Manager Cris Gallegos (408.517.2154) or Tony Frontino (714.544.1774) for more information.