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|                        |                                                                                                          |                                                                     |                               |
|-----------------------------|---------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------|------------------------------------|
| ARTICLE                I    |
|                        | TERM                OF AGREEMENT                                                                              |
|                        |                                                                                                          |                                                                     |                               |
| ARTICLE                II   |
|                        | DEFINITIONS                                                                                                   |
|                        | 2.1                                                                                                           | Agent                                                                    |
|                        | 2.2                                                                                                           | Agreement                                                                |
|                        | 2.3                                                                                                           | Buyer’s                Decremental Energy Value                    |
|                        | 2.4                                                                                                           | Capacity                Commitment                                       |
|                        | 2.5                                                                                                           | Capacity                Commitment Charge                                |
|                        | 2.6                                                                                                           | Central                Control Center                                    |
|                        | 2.7                                                                                                           | Chief                Executive Officer (CEO)                             |
|                        | 2.8                                                                                                           | Company                                                                  |
|                        | 2.9                                                                                                           | Company                Capability                                        |
|                        | 2.10                                                                                                          | Company                Demand                                            |
|                        | 2.11                                                                                                          | Company                Hourly Capability                                 |
|                        | 2.12                                                                                                          | Company                Load Responsibility                               |
|                        | 2.13                                                                                                          | Company                Operating Capability                              |
|                        | 2.14                                                                                                          | Company                Operating Reserve                                 |
|                        | 2.15                                                                                                          | Company                Peak Demand                                       |
|                        | 2.16                                                                                                          | Day                                                                      |
|                        | 2.17                                                                                                          | Economic                Dispatch                                         |
|                        | 2.18                                                                                                          | Energy                                                                   |
|                        | 2.19                                                                                                          | Entitlement                Energy                                        |
|                        | 2.20                                                                                                          | Generating                Unit                                           |
|                        | 2.21                                                                                                          | Hour                                                                     |
|                        | 2.22                                                                                                          | Internal                Economy Energy                                   |
|                        | 2.23                                                                                                          | Joint                Resource Plan                                       |
|                        | 2.24                                                                                                          | Joint                Unit                                                |
|                        | 2.25                                                                                                          | (a)                                                                      | Margin                on Sales     |
|                        |                                                                                                          | (b)                                                                      | Margin                on Purchases |
|                        |                                                                                                          | (c)                                                                      | Margin                             |
|                        | 2.26                                                                                                          | Month                                                                    |
|                        | 2.27                                                                                                          | Operating                Committee                                       |
|                        | 2.28                                                                                                          | Own                Load                                                  |
|                        | 2.29                                                                                                          | Parent                Company                                            |
|                        | 2.30                                                                                                          | Planning                Reserve Level                                    |
|                        | 2.31                                                                                                          | Pool                Energy                                               |
|                        | 2.32                                                                                                          | Power                                                                    |
|                        | 2.33                                                                                                          | Prorated                Reserve Level                                    |
|                        | 2.34                                                                                                          | Reserve                Capacity (Company or System)                      |
|                        | 2.35                                                                                                          | Seller’s                Incremental Energy Cost                    |
|                        | 2.36                                                                                                          | System                                                                   |
|                        | 2.37                                                                                                          | System                Capability                                         |
|                        | 2.38                                                                                                          | System                Demand                                             |
|                        | 2.39                                                                                                          | System                Load Responsibility                                |
|                        | 2.40                                                                                                          | System                Operating Capability                               |
|                        | 2.41                                                                                                          | System                Operating Reserve                                  |
|                        | 2.42                                                                                                          | System                Peak Demand                                        |
|                        | 2.43                                                                                                          | Variable                Cost                                             |
|                        | 2.44                                                                                                          | Year                                                                     |
|                        |                                                                                                          |                                                                     |
| ARTICLE                III  |
|                        | OBJECTIVES                                                                                                    |
|                        | 3.1                                                                                                           | Purpose                                                                  |
|                        |                                                                                                          |                                                                     |
| ARTICLE                IV   |
|                        | AGENT                                                                                                         |
|                        | 4.1                                                                                                           | Responsibility                of the Agent                               |
|                        | 4.2                                                                                                           | Delegation                and Acceptance of Authority                    |
|                        | 4.3                                                                                                           | Reporting                                                                |
|                        |                                                                                                          |                                                                     |
| ARTICLE                V    |
|                        | OPERATING                COMMITTEE                                                                            |
|                        | 5.1                                                                                                           | Operating                Committee                                       |
|                        | 5.2                                                                                                           | Delegation                of CEO Duties                                  |
|                        |                                                                                                          |                                                                     |
| ARTICLE                VI   |
|                        | OPERATIONS                                                                                                    |
|                        | 6.1                                                                                                           | Planning                and Authorization of Production Facilities  |
|                        | 6.2                                                                                                           | Planning                Reserve Levels                                   |
|                        | 6.3                                                                                                           | Provision                to Achieve Planning Reserve Levels              |
|                        | 6.4                                                                                                           | Capacity                Sales and Purchases and Reserve Shortfalls       |
|                        | 6.5                                                                                                           | Energy                Exchanges Among the Companies                      |
|                        | 6.6                                                                                                           | Energy                Exchange Pricing                                   |
|                        | 6.7                                                                                                           | Energy                Exchanges with non-Associated Entities             |
|                        | 6.8                                                                                                           | Communications                and Other Facilities                       |
|                        |                                                                                                          |                                                                     |
| ARTICLE                VII  |
|                        | CENTRAL                CONTROL CENTER                                                                         |
|                        | 7.1                                                                                                           | Central                Control Center                                    |
|                        | 7.2                                                                                                           | Expenses                                                                 |
|                        |                                                                                                          |                                                                     |
| ARTICLE                VIII |
|                        | GENERAL                                                                                                       |
|                        | 8.1                                                                                                           | Regulatory                Authorization                                  |
|                        | 8.2                                                                                                           | Effect                on Other Agreements                                |
|                        | 8.3                                                                                                           | Schedules                                                                |
|                        | 8.4                                                                                                           | Billings                                                                 |
|                        | 8.5                                                                                                           | Waivers                                                                  |
|                        | 8.6                                                                                                           | Successors                and Assigns; No Third Party Beneficiary        |
|                        | 8.7                                                                                                           | Amendment                                                                |
|                        | 8.8                                                                                                           | Independent                Contractors                                   |
|                        | 8.9                                                                                                           | Responsibility                and Liability                              |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                A   |
|                        | JOINT                UNIT                                                                                     |
|                        | 9.1                                                                                                           | Purpose                                                                  |
|                        | 9.2                                                                                                           | Ownership                                                                |
|                        | 9.3                                                                                                           | Contracts                                                                |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                B   |
|                        | COMPANY                UNITS THAT ARE NOT JOINT UNITS                                                         |
|                        | 10.1                                                                                                          | Purpose                                                                  |
|                        | 10.2                                                                                                          | Company                Units that Are Not Joint Units                    |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                C   |
|                        | CAPACITY                COMMITMENT CHARGE                                                                     |
|                        | 11.1                                                                                                          | Purpose                                                                  |
|                        | 11.2                                                                                                          | Basis                for Capacity Commitment                             |
|                        | 11.3                                                                                                          | Provisions                for Capacity Commitment Charge                 |
|                        | 11.4                                                                                                          | Provision                for Energy Charge                               |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                D   |
|                        | PAYMENTS                AND RECEIPTS FOR POOL ENERGY EXCHANGES AMONG THE                COMPANIES             |
|                        | 12.1                                                                                                          | Purpose                                                                  |
|                        | 12.2                                                                                                          | Hourly                Calculations                                  |
|                        | 12.3                                                                                                          | Receipts                and Payments                                     |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                E   |
|                        | PAYMENTS                AND RECEIPTS FOR INTERNAL ECONOMY ENERGY EXCHANGES AMONG THE                COMPANIES |
|                        | 13.1                                                                                                          | Purpose                                                                  |
|                        | 13.2                                                                                                          | Hourly                Calculations                                       |
|                        | 13.3                                                                                                          | Payments                                                                 |
|                        | 13.4                                                                                                          | Receipts                                                                 |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                F   |
|                        | DISTRIBUTION                OF MARGIN FOR OFF-SYSTEM ENERGY PURCHASES AND SALES                               |
|                        | 14.1                                                                                                          | Purpose                                                                  |
|                        | 14.2                                                                                                          | Distribution                of Margin                                    |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                G   |
|                        | DISTRIBUTION                OF OPERATING EXPENSES OF THE CENTRAL CONTROL CENTER                               |
|                        | 15.1                                                                                                          | Purpose                                                                  |
|                        | 15.2                                                                                                          | Costs                                                                    |
|                        | 15.3                                                                                                          | Distribution                of Costs                                     |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                H   |
|                        | CAPACITY                COMMITMENT UNITS                                                                      |
|                        | 16.1                                                                                                          | Purpose                                                                  |
|                        | 16.2                                                                                                          | Commitment                Units                                          |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                I   |
|                        | PLANNING-RESERVE                CRITERIA                                                                      |
|                        | 17.1                                                                                                          | Purpose                                                                  |
|                        | 17.2                                                                                                          | Planning                Reserve Criteria                                 |
|                        |                                                                                                          |                                                                     |
| SCHEDULE                J   |
|                        | STATEMENT                OF PRACTICE REGARDING OFF-SYSTEM ENERGY SALES                                        |
|                        | 18.1                                                                                                          | Purpose                                                                  |
|                        | 18.2                                                                                                          | Determination                of Energy Price Quotations                  |

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|                                    | PUBLIC                SERVICE COMPANY OF OKLAHOMA          |
|-----------------------------------------|------------------------------------------------------------|
| Attest                                  |                                                       |   |
|                                    |                                                       |   |
| /s/                Thomas G. Berkemeyer | By:                                                        | /s/                Stuart Solomon   |
| Assistant                Secretary      |                                                       | President |
|                                    |                                                       |   |
|                                    | SOUTHWESTERN                ELECTRIC POWER COMPANY         |
| Attest                                  |                                                       |   |
|                                    |                                                       |   |
| /s/                Thomas G. Berkemeyer | By:                                                        | /s/                Nicholas K. Akins   |
| Assistant                Secretary      |                                                       | President |
|                                    |                                                       |   |
|                                    | AMERICAN                ELECTRIC POWER SERVICE CORPORATION |
| Attest                                  |                                                       |   |
|                                    |                                                       |   |
| /s/                Thomas G. Berkemeyer | By:                                                        | /s/                J. Craig Baker   |
| Assistant                Secretary      |                                                       | Senior                Vice President |
|                                    |                                                       |   |

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| **COMPANY/UNIT                NAME** | **RATING****(MW)** | **YEAR****INSTALLED** |
|--------------------------------------|--------------------|-----------------------|
| **PSO**                              |               |                  |
| Riverside                #2          | 465                | 1976                  |
| Riverside                #1          | 457                | 1974                  |
| **SWEPCO**                           |               |                  |
| Know                Lee #5           | 344                | 1974                  |
| Wilkes                #3             | 351                | 1971                  |
|                                 |               |                  |

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