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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EXHIBIT 10.18 CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED WITH "[***]", HAS BEEN EXCLUDED BECAUSE IT IS NOT MATERIAL AND WOULD BE COMPETITIVELY HARMFUL IF PUBLICLY DISCLOSED. MASTER SUPPLY AGREEMENT THIS MASTER SUPPLY AGREEMENT ("Agreement") is made as of 31 October 2019 ("Effective Date") by and between Premier Nutrition Company, LLC, a Delaware limited liability company with its headquarters located at 1222 67th Street, Suite 210, Emeryville, CA 94608 ("Buyer" or "PNC"), and Fonterra (USA) Inc., a California corporation with its principal place of business located at 8700 W. Bryn Mawr Avenue, Suite 500N, Chicago, IL 60631 ("Supplier" or "Fonterra") (each a "Party", collectively "Parties"). WHEREAS PNC produces, distributes, markets and sells products including ready to drink protein shakes and beverages, powdered protein shakes, nutrition bars, and dietary supplements (the "Finished Products"); and WHEREAS Supplier produces raw materials including protein powders used by PNC to produce at least some of the Finished Products; NOW THEREFORE in consideration of their respective rights and obligations as set forth in this Agreement, and for other good and valuable consideration, the adequacy and receipt of which are acknowledged, PNC and Supplier agree as follows: 1 Supply of Ingredients 1.1 Supplier will provide such materials to PNC or its Third Party Manufacturers ("TPMs") as are specified in any Master Purchase Commitment or any other purchase orders that the Parties may execute from time to time during the term of this Agreement ("Ingredients"). Ingredients will be produced at Supplier's facilities listed in a Master Purchase Commitment, or any other of Supplier's facilities approved in advance, in writing by PNC. 1.2 PNC or its TPMs will place specific orders for Ingredients from Supplier by issuing a purchase order that specifies, at minimum, the item, quantities, price, delivery dates, and delivery and payment terms (each a "Purchase Order"). 1.3 PNC and Supplier may enter certain Master Purchase Commitments from time to time during the Term of this Master Supply Agreement. Such Master Purchase Commitments and any Purchase Orders issued against such Commitments shall be subject exclusively to the terms and conditions of this Agreement. In the event the terms of any Master Purchase Commitment conflicts with the terms of this Agreement, the terms of the Master Purchase Commitment shall control. 1.4 Supplier will receive Purchase Orders by telephone, USPS, overnight courier, email, and fax transmission, Monday through Friday except on state or nationally recognized bank holidays. Purchase Orders not received by 3:00 p.m. Eastern Time are considered to be received on the following Page 1 business day. Supplier will confirm or reject Purchase Orders within [***] of receipt of the Purchase Order. Orders not rejected in writing within such time will be deemed confirmed and accepted by Supplier. Each Purchase Order issued by PNC or its TPMs and accepted by Supplier shall be governed by the terms and conditions of this Agreement. Additional terms included in acknowledgments, standard terms and conditions, or any other documents or communications exchanged by the Parties in connection with the sale or purchase of any Ingredients shall be void and of no force or effect. The Parties may only modify, add to or amend any of the terms or conditions of this Agreement by a writing signed by authorized representatives of both Parties. 1.5 Supplier represents and warrants that at the time and date of delivery, the Ingredients will comply with all specifications ("Specifications"), a copy of which will be attached to the relevant Master Purchase Commitment or Purchase Order accordingly. A Specification may be updated from time to time by PNC in its sole discretion, provided PNC provides Supplier with reasonable prior notice on any updates ("Change Notification"). Within [***] from receipt of the Change Notification, Supplier will either: (1) accept the Specification change at the current price and terms; or (2) submit to PNC a proposal ("Proposal") setting forth the conditions of acceptance that may include a change in price and/or other terms, including documentation to support same. Within [***] the Parties will discuss the Proposal in good faith and exercise their best efforts to agree on the appropriate adjustment if any. PNC will not issue any Purchase Orders, nor be required to issue any Purchase Orders to Supplier until PNC and Supplier have agreed on required Ingredient Specifications and any associated price and/or term adjustment. In the event the Parties fail to agree on required Ingredient Specifications or price and/or term adjustments despite their best good faith efforts, neither Party will have any further obligation with regard to purchase
"""

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

assistant: 31 October 2019