system: You are a contract-analysis assistant performing a span-extraction task. You are given an excerpt from a commercial contract and the name of a clause type to locate within it.

Return the exact text of the requested clause, copied verbatim from the excerpt — identical wording and punctuation, with no paraphrasing, summarising, explanation, or added commentary.

The excerpt is one window of a much longer contract and often will not contain the requested clause. If the requested clause does not appear in this excerpt, respond with exactly: Not found.

Output only the extracted clause text, or the exact string `Not found.` — nothing else.

user: Contract excerpt:
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of Vendor's Personnel and Equipment 57 4.14Independent Contractor 57 4.15Inspection of Material 58 4.16Inspection of Work 58 4.17Liens 58 4.18Notification of Injury or Damage 59 4.19Protection of Property 59 4.20Releases Void 59 4.21Removal and Management of Used Batteries 59 4.22Resource Recovery Center 60 Proprietary and Confidential This Agreement and information contained therein is not for use or disclosure outside of AT&T, its Affiliates, and third party representatives, and Vendor except under written agreement by the contracting parties. 4 Source: ATN INTERNATIONAL, INC., 10-Q, 11/8/2019 Mobility Network General Agreement TABLE OF CONTENTS 4.23Safety Management 60 4.24Technical Support 61 4.25Testimony 61 4.26AT&T Data and AT&T Derived Data (Big Data) 61 4.27Business Continuity Plan 63 4.28Change in Laws 63 4.29FOSS 63 5.1 Execution of Agreement 64 5.2 Transmission of Original Signatures and Executing Multiple Counterparts 64 Exhibit A: Government Flow Downs and Contract Clauses Exhibit B: Supplier Information Security Requirements (SISR) Exhibit C: Change Management Plan Addendum 1: Network Build and Structured Payments Addendum 2: Maintenance Proprietary and Confidential This Agreement and information contained therein is not for use or disclosure outside of AT&T, its Affiliates, and third party representatives, and Vendor except under written agreement by the contracting parties. 5 Source: ATN INTERNATIONAL, INC., 10-Q, 11/8/2019 This Network Build and Maintenance Agreement is entered into as of the 31 day of July, 2019 (the "Effective Date") by and between Commnet Wireless, LLC, a Delaware limited liability company (hereinafter referred to as "Vendor"), and AT&T Mobility LLC, a Delaware limited liability company on behalf of itself and its Affiliates (as such term is defined herein) (collectively and hereinafter referred to as "AT&T"), each of which may be referred to in the singular as a "Party" or in the plural as the "Parties." 1.0 Scope 1.1 Scope of Agreement. Subject to the terms and conditions of this Agreement, Vendor shall (i) build, install and deploy a radio access network ("RAN") at certain Cell Sites in one or more states for AT&T and its Affiliates as more particularly described in Addendum 1: Network Build and Structured Payments (the "Build Addendum") attached hereto, (ii) provide ongoing maintenance of the RAN network constructed by Vendor pursuant to the Build Addendum as more particularly described in Addendum 2: Maintenance (the "Maintenance Addendum") attached hereto and (iii) provide to AT&T certain other Material and Services related thereto as described herein and therein. In exchange for the provision of the Material and Services set forth in the Build Addendum, the Parties agree that AT&T will pay to Vendor the Structured Payments (as such term is defined in the Build Addendum) and in exchange for the provision of the Material and Services set forth in the Maintenance Addendum, the Parties agree that AT&T will pay to Vendor the Maintenance Fees (as such term is defined in the Maintenance Addendum). Vendor agrees that the Material and Services provided pursuant to this Agreement, the Build Addendum and the Maintenance Addendum shall strictly conform to the Specifications contained herein and therein. Concurrently herewith, the Parties or their Affiliates have entered into (i) that certain Cell Site Backhaul Master Services Agreement between Vendor and AT&T Corp. pursuant to which Vendor is responsible for providing transport services from the Cell Sites to AT&T's designated MTSO (the "Transport Agreement") and (ii) that certain Master License Agreement that governs all site license agreements between AT&T and Vendor (or its Affiliates) for the Cell Sites (the "Master License Agreement"). 1.2 Term of Agreement. The "Term" of this Agreement shall commence on the Effective Date and shall continue in full force and effect until the expiration or earlier termination of the last Addendum to expire or be terminated, at which time this Agreement will expire, unless this Agreement is sooner terminated in accordance with the terms and provisions of this Agreement. 2.0 Definitions 2.1 Affiliate. "Affiliate" of a Person means any other Person, directly or indirectly, through one or more intermediaries, Controlling, Controlled by or under common Control with such Person or any other Person in which such Person beneficially owns a majority of the outstanding capital stock, membership interests or partnership interests. Proprietary and Confidential This Agreement and information contained therein is not for use or disclosure outside of AT&T, its Affiliates, and third party representatives, and Vendor except under written agreement by the contracting parties. 1 st Source: ATN INTERNATIONAL, INC., 10-Q, 11/8/2019 2.2 Agreement. "Agreement" means the written agreement between the Parties as set forth in this document and the attached addendums, exhibits, schedules and appendices and
"""

Extract the exact clause related to "Expiration Date" from the excerpt above.

assistant: The "Term" of this Agreement shall commence on the Effective Date and shall continue in full force and effect until the expiration or earlier termination of the last Addendum to expire or be terminated, at which time this Agreement will expire, unless this Agreement is sooner terminated in accordance with the terms and provisions of this Agreement.