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:
"""
hereof. CLAUSE NINTH OBLIGATIONS OF THE SHIPPER 9.1 In addition to the obligations set forth in the Manual of the Shipper and those established in the law, ECOPETROL is obliged in a special manner to: CLAUSE TENTH OBLIGATIONS OF THE SENDER 10.1 In addition to the obligations set out in the Manual of the Shipper and those in the law, the SENDER is obliged particularly to: a) Receive in the Entrance Point agreed in the Pipeline, the Crude owned by the SENDER up to the volume corresponding to the Contracted Capacity, subject to the Available Capacity of the Pipeline in the Month of Operation in which the Service is to be provided. b) Maintain in custody the Crude delivered from the Point of Entrance until the time of delivery to the SENDER in the Exit Point. Notwithstanding the foregoing, in the event in which the SENDER does not receive the Crude in the Point of Exit pursuant to the agreement, the responsibility by the ECOPETROL to maintain the Crude in custody shall cease. c) Shipping and decanting through the Pipeline the Crude delivered by the SENDER from the Point of Entrance until the Exit Point. d) Store the Crude from its reception in the Point of Entrance until delivered to the SENDER in the Point of Exit, exclusively to facilitate its shipment under the Contract hereof, not including the storage for export or the segregate storage of Crude. e) Deliver the Crudes shipped to the SENDER or whoever is designated as receiver of the same in the Point of Exit, in accordance with the instructions received by the SENDER and with the conditions of the Manual of the Shipper. f) ECOPETROL shall not be obliged to receive Crude: (a) when the same fails to fulfill the Specifications of Quality agreed in the Contract hereof; (b) when the SENDER does not have an accepted nomination in the Shipment Schedule of the Pipeline, or (c) when there are not valid agreements of the SENDER that allow the delivery of Crude in the Point of Exit. g) Execute all other obligations derived from the nature of the Contract. 5 CLAUSE ELEVENTH RISKS AND RESPONSIBILITY 11.1 Each Party shall be responsible for any damage caused to the other Party as a result of failing to fulfill its obligations under the Contract hereof, in the terms set out in the clause hereof. 11.2 Responsibility of ECOPETROL: a) Undertake the nomination of the Crudes to be shipped, pursuant to the procedure established in the Manual of the Shipper. b) Deliver at the Point of Entrance the Crudes of its own/production included in the Shipment Schedule as a result of the nomination process. c) Receive in the Point of Exit the Crudes transported as established in the Manual of the Shipper and the procedures set forth by ECOPETROL, or if a receiver different than the SENDER has been designated, this shall take al necessary measures so that the Crude is received in accordance with the stipulations in the Manual of the Shipper and the procedures set out by ECOPETROL, the SENDER is any case responsible for the reception of the Crude. In case the Crude is not received at the Point of Exit, the provisions established in the Manual of the Shipper shall be applied. d) Enter into the contracts with other shippers or terminal operators required to ensure the delivery of crudes at the Point of Exit without affecting the operation of the Pipeline. e) Make the Fee payment and all other items as they may apply in the terms and conditions established in the Contract hereof. f) Execute the bond in favor of ECOPETROL. g) Make the payment of the shipping tax under the conditions set out in this Contract and the law. h) Execute all other obligations derived from the nature of the Contract. a) In addition to the provisions in the Manual of the Shipper, ECOPETROL shall not be responsible for any faults in the Service, or the loses, damage or deterioration the Crude may suffer, if the fault in the Service, the loss, damage or deterioration of the Crude are due to (i) events of force majeure or acts of nature, (ii) Acts from third parties, (iii) vice inherent to the Crude, or (iv) fault attributable to the Sender (hereinafter, the "Excusable Events"). b) ECOPETROL shall only be responsible for the faults in the Service or loses, damage or deterioration the Crude may suffer to the extent it does not demonstrate that
"""

Extract the exact clause related to "Warranty Duration" from the excerpt above.