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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the claim promptly on notice of such claim being received by the SCIEN; · No admissions of liability or compromise or offer of settlement of any claim shall be made by SCIEN without the prior written consent of HEMISPHERX; and · HEMISPHERX shall have full control over any claim, proceedings or settlement negotiations in respect of which it is providing the indemnity. Subject to clause X.B 1.), SCIEN shall defend and indemnify HEMISPHERX and its Affiliates and hold each of them harmless against all claims, demands, actions, losses, expenses, damages, liabilities, costs (including interest, penalties and reasonable attorneys' fees) and judgements suffered by each of them, which arise out of SCIEN's negligent or wilful acts or omissions or which otherwise arise out of SCIEN's breach of the Agreement. Survivability. The obligations set forth in this Section X. shall survive the termination of this Agreement for the legal periods of limitation provided by US law. {***} Confidential portions of this exhibit have been redacted and filed separately with the Commission pursuant to a confidential treatment request in accordance with Rule 24b-2 of the Securities Exchange Act of 1934, as amended. Page 7 of 28 XI. CONFIDENTIALITY A. SCIEN and HEMISPHERX agree to keep secret and confidential all confidential, proprietary or non-public information ("Confidential Information") of the other Party .This provision shall survive termination or expiration of this Agreement. B. Such Confidential Information will be kept confidential until 5 years after the expiration of termination of this Agreement. Notwithstanding the foregoing , Confidential Information of a Party shall not include information which the other Party can establish by written documentation was (a) to have been publicly known prior to disclosure of such information by the disclosing Party to the other Party, (b) to have become publicly known, without fault on the part of the other Party, subsequent to disclosure of such information by the disclosing Party to the other Party, (c) to have been received by the other Party at any time from a source , other than the disclosing Party, rightfully having possession of and the right to disclose such information, (d) to have been otherwise known by the other Party prior to disclosure of such information by the disclosing Party to the other Party, or (e) to have been independently developed by employees or agents of the other Party without access to or use of such information disclosed by the disclosing Party to the other Party. C. The confidentiality obligations contained in this section XI shall not apply to the extent that the receiving Party (the "Recipient") is required (a) to disclose information by law, order or regulation of a governmental agency or a court of competent jurisdiction , or (b) to disclose information to any governmental agency for purposes of obtaining approval to test or market a Product , provided in either case that the Recipient shall provide written notice thereof to the other Party and sufficient opportunity to object to any such disclosure or to request confidential treatment thereof. XII. PROSECUTION, INFRINGEMENT, AND DEFENSE OF HEMISPHERX INTELLECTUAL PROPERTY A. HEMISPHERX will be responsible for and shall control, at its expense, the preparation, filing, prosecution and maintenance of HEMISPHERX Intellectual Property. B. SCIEN will cooperate in all reasonable ways to establish and protect HEMISPHERX Intellectual Property in the Territory. C. HEMISPHERX, at its expense, will have the right to determine the appropriate course of action to enforce its HEMISPHERX Intellectual Property against infringement or otherwise abate the infringement thereof , to take (or refrain from taking) appropriate action to enforce its HEMISPHERX Intellectual Property, to control any litigation or other enforcement action and to enter into, or permit, the settlement of any such litigation or other enforcement action with respect to its Intellectual Property . D. Each Party shall promptly notify the other Party in writing if any claim, action, demand or other proceeding (a "Claim") is brought against or is threatened to be brought against such Party alleging that the sale of Product violates another party's intellectual property. E. SCIEN will promptly notify HEMISPHERX of any Third party SCIEN knows or believes may be infringing HEMISPHERX Intellectual Property and will, to the greatest extent reasonably possible, provide to HEMISPHERX any information SCIEN has in support of such belief. HEMISPHERX will have the right, but not the obligation, to use such information in an infringement action against such third Party. SCIEN agrees to cooperate with HEMISPHERX in any action for infringement of HEMISPHERX, and HEMISPHERX will reimburse SCIEN for
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Extract the exact clause related to "Covenant Not To Sue" from the excerpt above.