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, respectively, the Otis Group and the Carrier Group, hereby irrevocably assign to UTC, and agree and promise to assign to UTC, (a) any and all rights, title and interest in and to the United Technologies Trademarks, including all goodwill appurtenant thereto held by them and the other members of the Otis Group and the Carrier Group, and (b) any and all registrations and applications for registration of Trademarks consisting of or containing any of the United Technologies Trademarks, anywhere in the world, to which Otis, Carrier or another member of the Otis Group or the Carrier Group holds a legal or equitable interest as of the Effective Time. Without limitation, the foregoing assignment and promise of assignment includes the right to sue and recover damages for past and future infringements of the United Technologies Trademarks and to bring any proceeding in the United States Patent and Trademark Office or any equivalent agency or governing body in any other country for cancellation, opposition, or other proceeding in connection with the United Technologies Trademarks. Except as expressly stated in Section 4.2, none of Otis, Carrier or any other member of the Otis Group or the Carrier Group shall have any right, title or interest in or to any of the United Technologies Trademarks, and any and all use of the United Technologies Trademarks, whether or not authorized pursuant to Section 4.2, shall inure solely and exclusively to UTC for all purposes. 10 4.1.2 Otis and Carrier, on behalf of themselves and the other members of, respectively, the Otis Group and the Carrier Group, agree and promise to assist UTC and the other members of the UTC Group, at UTC's request, in UTC's discretion and at UTC's cost, in applying for, registering, maintaining, renewing, demonstrating use of, recording UTC's and the other members of the UTC Group's rights in, and otherwise perfecting, and defending and enforcing against third party infringers, the rights of UTC and the other members of the UTC Group in the United Technologies Trademarks and all goodwill associated therewith, including executing, verifying, acknowledging and delivering any and all documents, including any instruments of transfer and recordable assignments, and confirmations of use, and performing such other acts deemed necessary in the reasonable opinion of UTC. 4.1.3 Otis and Carrier, on behalf of themselves and the other members of, respectively, the Otis Group and the Carrier Group, agree and promise not to (a) challenge in any jurisdiction or venue the right or title of UTC or any other members of the UTC Group in and to any United Technologies Trademark, or the validity or enforceability of any United Technologies Trademark or any registration thereof, or (b) register or renew, attempt to register or renew, or assist a Person other than UTC or a member of the UTC Group in registering or renewing, any United Technologies Trademark. 4.2 Use of United Technologies Trademarks 4.2.1 Except as expressly provided in this Section 4.2, after the Effective Time, none of Otis, Carrier or any other members of the Otis Group or the Carrier Group shall use, or have the right to use, any of the United Technologies Trademarks. 4.2.2 Without limitation, Otis and Carrier as promptly as reasonably practicable (but in any case within six (6) months of the Effective Time) shall cause each member of, respectively, the Otis Group and the Carrier Group having a corporate name that includes any of the United Technologies Trademarks to apply to change its corporate name to a name that does not include any of the United Technologies Trademarks, including, within six (6) months of the Effective Time, by making any legal filings in each relevant jurisdiction necessary to effect such change worldwide. 4.2.3 UTC, on behalf of itself and the other members of the UTC Group, hereby grants to Otis, Carrier and the other members of the Otis Group and the Carrier Group a limited, non-exclusive, non-transferable, personal and nonsublicensable right to continue temporarily to use, following the Effective Time, any United Technologies Trademark it is using immediately prior to the Effective Time, solely to the extent of such pre- Separation use and in accordance with product quality standards and programs in place at the respective member of the Otis Group or the Carrier Group immediately prior to the Effective Time, and strictly in accordance with this Section 4.2.3; provided that Otis and Carrier shall, and shall cause each of its respective Affiliates (including, after the Effective Time, the members of, respectively, the Otis Group and
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Extract the exact clause related to "Covenant Not To Sue" from the excerpt above.

assistant: Otis and Carrier, on behalf of themselves and the other members of, respectively, the Otis Group and the Carrier Group, agree and promise not to (a) challenge in any jurisdiction or venue the right or title of UTC or any other members of the UTC Group in and to any United Technologies Trademark, or the validity or enforceability of any United Technologies Trademark or any registration thereof, or (b) register or renew, attempt to register or renew, or assist a Person other than UTC or a member of the UTC Group in registering or renewing, any United Technologies Trademark.