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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identity and reputation of the Brand, and you will comply with such requirements. Unless we specify otherwise, you may purchase products from any authorized .source of distribution; however, we reserve the right, in our business judgment, to enter into exclusive purchasing arrangements for particular products or services and to require that you purchase products or services from approved suppliers or distributors; 5.1.4 install, display, and maintain signage displaying or containing the Brand name and other distinguishing characteristics in accordance with Standards we establish for System Hotels; 5.1.5 comply with Standards for the training of persons involved in the operation of the Hotel, including completion by the General Manager and other key personnel of the Hotel of a training program for operation of the Hotel under the System, at a site we designate. You will pay us all fees and charges, if any, we require for your personnel to attend these training programs. You are responsible for all travel, lodging and other expenses you or your employees incur in attending these programs; 5.1.6 purchase and maintain property management, revenue management, in-room entertainment, telecommunications, high-speed Internet access, and other computer and technology systems that we designate for the System or any portion of the System based on our assessment of the long-term best interests of System Hotels, considering the interest of the System as a whole; 5.1.7 advertise and promote the Hotel and related facilities and services on a local and regional basis in a first-class, dignified manner, using our identity and graphics Standards for all System Hotels, at your cost and expense. You must submit to us for our approval samples of all advertising and promotional materials that we have not previously approved (including any materials in digital, electronic or computerized form or in any form of media that exists now or is developed in the future) before you produce or distribute them. You will not begin using the materials until we approve them. You must immediately discontinue your use of any advertising or promotional material we disapprove, even if we previously approved the materials; 5.1.8 participate in and pay all charges in connection with all required System guest complaint resolution programs, which programs may include chargebacks to the Hotel for guest refunds or credits and all required System quality assurance programs, such as guest comment cards, customer surveys and mystery shopper programs. You must maintain minimum performance Standards and scores for quality assurance programs we establish; 9 5.1.9 honor all nationally recognized credit cards and credit vouchers issued for general credit purposes that we require and enter into all necessary credit card and voucher agreements with the issuers of such cards or vouchers; 6.1.10 participate in and use the Reservation Service, including any additions, enhancements, supplements or variants we develop or adopt, and honor and give first priority on available rooms to all confirmed reservations referred to the Hotel through the Reservation Service. The only reservation service or system you may use for outgoing reservations referred by or from the Hotel to other Network Hotels will be the Reservation Service or other reservation services we designate; 5.1.11 comply with Laws and, on request, give evidence to us of compliance; 5.1.12 participate in, and promptly pay all fees, commissions and charges associated with, all travel agent commission programs and third-party reservation and distribution services (such as airline reservation systems), all as required by the Standards and in accordance with the terms of these programs, all of which may be modified; 5.1.13 not engage, directly or indirectly, in any cross-marketing or cross-promotion of the Hotel with any Other Hotel or related business, without our prior written consent. You agree to refer guests and customers, wherever reasonably possible, only to System Hotels or Network Hotels. We may require you to participate in programs designed to refer prospective customers to Other Hotels. You must display all material, including brochures and promotional material we provide for System Hotels and Network Hotels, and allow advertising and promotion only of System Hotels and Network Hotels on the Hotel Site, unless we specifically direct you to include advertising or promotion of Other Hotels; 5.1.14 treat as confidential the Standards, the Manual and all other Proprietary Information. You acknowledge and agree that you do not acquire any interest in the Proprietary Information other than the right to utilize the same in the development and operation of the Hotel under the terms of this Agreement. You agree that you will not use the Proprietary Information in any business or for
"""

Extract the exact clause related to "Exclusivity" from the excerpt above.

assistant: The only reservation service or system you may use for outgoing reservations referred by or from the Hotel to other Network Hotels will be the Reservation Service or other reservation services we designate;