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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on behalf of itself and the other members of the Licensor Group, and solely to the extent the Licensor Party or another member of the Licensor Group has the right to do so, hereby grants and agrees to grant to the applicable Licensee Party and the other members of the Licensee Group, subject to the field restriction of Section 3.1.2, a royalty-free, nonexclusive, perpetual, irrevocable, fully paid-up, worldwide right and license, with the right to sublicense as provided in Section 3.1.3, to Exploit Intellectual Property Rights that are owned by the Licensor Party or another member of the Licensor Group immediately following the assignments pursuant to Article II and meet one or more of the following descriptions with respect to the relevant Licensee Party: (a) the Intellectual Property Rights are rights under Licensed Patents or other Intellectual Property Rights that, in each case, as of the Effective Time, are either (A) used in connection with, or necessary for the ongoing conduct of, the current business of the Licensee Party or another member of the Licensee Group, or (B) Contemplated to be Used in the business of the Licensee Party, or another member of the Licensee Group, in the Licensee Group Field; provided, however, that the license granted in this Section 3.1.1(a) does not apply to the Intellectual Property Rights received under or otherwise governed by an Excluded Agreement; and/or (b) the Intellectual Property Rights are embodied in an invention, or proposed invention, that is both (i) described in a Patent or Invention Disclosure held by the Licensor Party or another member of the Licensor Group and (ii) conceived by at least one inventor who, at the time of conception, was employed by a member of the Licensee Group, a non-inclusive list of which inventions and proposed inventions are provided in Schedule 3.1.1(b), provided, however, that the license granted in this Section 3.1.1(b) does not apply to an invention conceived under or otherwise governed by an Excluded Agreement; and/or (c) the Intellectual Property Rights are subject to an assignment to the Licensor Party in Section 2.1.1(b) concerning Performer Foreground-Delivered IPR conceived or created in the course of services concerning which the Licensor Party or another member of the Licensor Group was the Requester and the Licensee Party or another member of the Licensee Group was the Performer; and/or 8 (d) the Intellectual Property Rights are Performer Background IPR or Patent rights of the Licensor Party or another member of the Licensor Group and is necessary for the Licensee Party or another member of the Licensee Party to Exploit the Performer Foreground-Delivered IPR in the Licensee Group Field, provided, however, that the license granted in this Section 3.1.1(d) applies only to the extent necessary for the Licensee Party or another member of the Licensee Group to Exploit the Performer Foreground-Delivered IPR in the Licensee Group Field. (collectively, "Licensed Intellectual Property Rights"). 3.1.2 Field Restriction. The licenses granted in Section 3.1.1 are limited to, and a Licensee Party and the other members of the Licensee Group will have the right to Exploit, only the Licensed Intellectual Property Rights within the Licensee Group Field, except for the purposes of research and development at a stage encompassed within U.S. Department of Defense Technology Readiness Levels 1-6 or NASA Technology Readiness Levels 1-6; provided that (a) such research is not intended for use outside the Licensee Group Field, and (b) in the course of research conducted for a third party outside the Licensee Group Field, neither the Licensee Party nor any member of the Licensee Group (nor any of their respective officers, directors, employees, contractors, agents or sublicensees) shall disclose such Intellectual Property Rights to the third party. 3.1.3 Sublicense of Licensed Intellectual Property Rights. A Licensee Party or another member of the Licensee Group may sublicense its rights in Licensed Intellectual Property Rights hereunder, solely in support of its respective businesses (and not independent of its current or future products and related services). In all cases in which the exercise of sublicense rights hereunder reasonably requires disclosure of Licensed Intellectual Property Rights to a third party, the applicable member of the Licensee Group will disclose such Licensed Intellectual Property Rights (a) solely on a "need to know" basis, (b) provided that the Person to receive Licensed Intellectual Property Rights first agrees in writing to terms of confidentiality and non-use at least as restrictive as those provided in this Agreement, and (c) provided that the Licensee Party ensures the performance of, and accepts joint and several
"""

Extract the exact clause related to "Irrevocable Or Perpetual License" from the excerpt above.

assistant: (d) the Intellectual Property Rights are Performer Background IPR or Patent rights of the Licensor Party or another member of the Licensor Group and is necessary for the Licensee Party or another member of the Licensee Party to Exploit the Performer Foreground-Delivered IPR in the Licensee Group Field, provided, however, that the license granted in this Section 3.1.1(d) applies only to the extent necessary for the Licensee Party or another member of the Licensee Group to Exploit the Performer Foreground-Delivered IPR in the Licensee Group Field.