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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activities shall be at PaperExchange's sole cost and expense. 2.7. VerticalNet will provide, install, repair, maintain and pay for the communications, computer and peripheral equipment, services and facilities supporting the Co-Branded Sites. VerticalNet shall maintain the Co-Branded Sites in a high quality and professional manner consistent with its maintenance of other VerticalNet Sites. VerticalNet and PaperExchange shall be responsible for the sale of all advertising on the Co-Branded Sites; provided, however, that neither party shall sell advertising on the Co-Branded Sites to a competitor (as defined in 1.16 and 1.25) and provided that each party shall submit any proposed advertising for the Co-Branded Sites to the other party for its prior written approval, such approval not to be unreasonably withheld, delayed or conditioned. 2.8. VerticalNet shall be solely responsible for the development, operation and maintenance of Pulp and Paper Online and for all materials that appear on Pulp and Paper Online, except for the PaperExchange Content. 2.9. PaperExchange shall be solely responsible for the development, operation and maintenance of the PaperExchange Site and for all materials that appear on the PaperExchange Site, except for the VerticalNet Content and the VerticalNet Archived Content. 3. VERTICALNET CONTENT 3.1. VerticalNet shall provide or make available to PaperExchange, for use in accordance with the provisions of this Agreement, (a) the full text of all original content (headlines, feature articles, columns and case studies) created from time to time by the Managing Editor of Pulp and Paper Online, and (b) the content created from time to time by guest columnists for Pulp and Paper Online, to the extent such columnists have approved the provision of such content by VerticalNet to PaperExchange. VerticalNet shall provide such content (the "VerticalNet Content") to PaperExchange twice per week, in two "batches" of the VerticalNet Content created or acquired since the last provision of VerticalNet Content by VerticalNet to PaperExchange. 3.2. VerticalNet hereby grants to PaperExchange a non-exclusive, non-transferable license to use, reproduce, display and transmit the VerticalNet Content, solely in connection with the development, maintenance and operation of the PaperExchange Site, subject to and in accordance with the terms, conditions and provisions of this Agreement. PaperExchange may 5 reproduce, display and transmit any VerticalNet Content for up to three weeks on the PaperExchange Site, and after the expiration of such three week period PaperExchange shall cease to reproduce, display and transmit such VerticalNet Content and remove such VerticalNet Content from the PaperExchange Site. 3.3. PaperExchange shall place a VerticalNet Link in a mutually agreeable location and size on each page of the PaperExchange Site that contains all or a portion of the VerticalNet Content. 3.4. PaperExchange shall list on a mutually acceptable page of the PaperExchange Site headlines and abstracts of the VerticalNet Content then reproduced, displayed and transmitted on the PaperExchange Site. PaperExchange shall place two VerticalNet Links in mutually agreeable locations and sizes on such page of the PaperExchange Site, the first of which will take users to the Buyer's Guide on Pulp and Paper Online, and the second of which will take users to the Professional e-Bookstore on Pulp and Paper Online. VerticalNet and PaperExchange shall mutually agree upon the method of implementing such links. 3.5. PaperExchange shall not remove any titles or any trademark, copyright or patent notices, or any proprietary or restricted rights notices that appear on the VerticalNet Content and/or the VerticalNet Archived Content. All such titles and notices must be reproduced on all permitted copies of the VerticalNet Content and/or the VerticalNet Archived Content. 3.6. During the Term, VerticalNet will not disclose, transfer or otherwise provide the VerticalNet Content and/or the VerticalNet Archived Content to any PaperExchange Competitor. 4. ADVERTISING 4.1. Advertisements on the PaperExchange Site. 4.1.1. During the Term, VerticalNet shall have the exclusive right to arrange for the sale of ***** of the third party advertising inventory (which shall consist of a minimum of one advertisement per page on each of the "Co-Branded Equipment," "Co-Branded Careers," "Resources" and "Home Page" sections or successor, replacement or substitute sections) of the PaperExchange Site and shall be consistent with the amount of advertising on other business to business vertical sites on the PaperExchange Site (the "Third Party Advertising Allocation"). PaperExchange shall retain the right to place advertisements for its own account on the remaining ***** of the Third Party Advertising Allocation; provided, however, that if any portion of such Third Party Advertising Allocation remains unsold 45 days after it becomes available for advertising, VerticalNet shall have the exclusive right to arrange for third
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Extract the exact clause related to "Parties" from the excerpt above.