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 4 Rare Element Resources Ltd. EXECUTION COPY IP Rights Agreement INTELLECTUAL PROPERTY RIGHTS AGREEMENT Synchron, a California corporation having a principal place of business at 3550 General Atomics Court, San Diego, CA 92121-1122 (or one or more Affiliates, the "Investor"), and Rare Element Resources Ltd., a British Columbia Corporation having a principal place of business at P.O. Box 271049, Littleton, Colorado 80127 (the "Company") (Investor and Company each a "Party" and together the "Parties"), agree as follows: I. Background of Agreement 1.00 Company is the owner of certain Patents and related Technical Information relating to rare earth mineral processing and rare earth separation. 1.01 Investor wishes to acquire certain rights under the Patents and related Technical Information in accordance with the terms of this IP Agreement. 1.02 Company and Investor are concurrently entering into an Investment Agreement ("Investment Agreement") whereby Investor is making a monetary investment in Company. 1.03 Company is issuing the Option pursuant to which Investor will be entitled to purchase common shares of Company. II. Definitions As used herein, the following terms have the meaning set forth below: 2.01 Any term set out in this IP Agreement with its initial letters capitalized, shall have the same meaning as it has in the Investment Agreement, unless a different meaning is explicitly assigned to the term in this IP Agreement. 2.02 "Affiliate" has the meaning set forth in the Investment Agreement. 2.03 "Business Day" has the meaning set forth in the Investment Agreement. 2.04 "Company" has the meaning set out above in the introductory paragraph. 2.05 "Company Improvements" has the meaning set out below in Article 5.00. Page 1 of 15 Source: RARE ELEMENT RESOURCES LTD, SC 13D, 10/19/2017 Rare Element Resources Ltd. EXECUTION COPY IP Rights Agreement 2.06 "Dispute" has the meaning set out below in Article 18.00. 2.07 "Dispute Notice" has the meaning set out below in Article 18.00. 2.08 "Effective Date" has the meaning of the "Closing Date" set forth in the Investment Agreement. 2.09 "Escalation to Mediation Date" has the meaning set out below in Article 18.01. 2.10 "Improvement" or "Improvements" means any modification of a process or other technology described in a Patent, and any modification to Technical Information. 2.11 "Investment Agreement" has the meaning set out above in Article 1.02. 2.12 "Investor" has the meaning set out above in the introductory paragraph. 2.13 "Investor Improvements" has the meaning set out below in Article 5.01. 2.14 "IP Agreement" means this agreement, including all Exhibits referenced herein and attached hereto. 2.15 "Joint Improvements" has the meaning set out below in Article 5.02. 2.16 "Option" has the meaning set forth in the Investment Agreement. 2.17 "Option Period" has the meaning set forth in the Investment Agreement. 2.18 "Patent" or "Patents" means: (a) any and all patents and patent applications owned by Company anywhere in the world as of the Effective Date relating to rare earth mineral processing and rare earth separation including without limitation those patents and patent applications listed in Exhibit A; (b) any and all divisions, continuations, continuations-in-part of any of the patents and patent applications within subdivision (a); (c) any and all patents that may directly or indirectly issue from any patent applications within subdivisions (a) and (b); (d) any and all re- issues, substitutes and extensions of any of the patents within subdivisions (a), (b) and (c); and (e) any and all counterparts or equivalents to any of the foregoing in any country of the world. 2.19 "Party" and "Parties" have the meanings set out above in the introductory paragraph. Page 2 of 15 Source: RARE ELEMENT RESOURCES LTD, SC 13D, 10/19/2017 Rare Element Resources Ltd. EXECUTION COPY IP Rights Agreement 2.20 "Person" has the meaning set forth in the Investment Agreement. 2.21 "Technical Information" means research and development information that is published or unpublished, unpatented inventions, know-how, trade secrets, and technical data in the possession of Company at the Effective Date of this IP Agreement or developed by Company during the term of this IP Agreement that relate to rare earth mineral processing and rare earth separation. 2.22 "Third Party" means a Person other than Investor, the Company or one of their Affiliates. III. License 3.00 Company grants to Investor, for the duration of the Option Period, a worldwide, royalty-free, non-exclusive, irrevocable license (with the right to grant sublicenses to Affiliates) under the Patents to practice the methods therein described and claimed and to make and have made, use, offer to sell, sell and import products made using such methods,
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Extract the exact clause related to "Effective Date" from the excerpt above.

assistant: "Effective Date" has the meaning of the "Closing Date" set forth in the Investment Agreement.