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:
"""
TREATMENT WITH RESPECT TO CERTAIN PORTIONS OF THIS AGREEMENT ACCORDINGLY, CERTAIN PORTIONS HAVE BEEN REDACTED Exhibit 10.1 SPONSORSHIP AGREEMENT This agreement ("Agreement") is entered into as of the 31st day of March, 1998 ("Effective Date"), by and between Excite, Inc., a California corporation, located at 555 Broadway, Redwood City, California 94063 ("Excite"), and CyberShop, a Delaware corporation, located at 130 Madison Avenue, New York, New York 10016 ("Client"). RECITALS A. Excite maintains a site on the Internet at http://www.excite.com (the "Excite Site"), a site at http://www.webcrawler.com (the "WebCrawler Site") and owns, manages or is authorized to place advertising on affiliated Web sites worldwide (collectively, the "Excite Network") which, among other things, allow its users to search for and access content and other sites on the Internet. B. Within the Excite Site and the WebCrawler Site, Excite currently organizes certain content into topical channels, including "shopping" channels (the "Shopping Channels"). C. Client operates an on-line department store at its Web site located at http:// cybershop.com (the "Client Site"). D. Client wishes to promote its business to Excite's users through promotions and advertising in various portions of the Excite Network. Therefore, the parties agree as follows: 1. SPONSORSHIP OF THE SHOPPING CHANNELS a) Commencing on the Launch Date (as defined below), Client will be promoted in the Excite Shopping Channel and the WebCrawler Shopping Channel: i) A link to the Client Site (consistent with the format used on similar links on the same page) will be displayed in the Excite Shopping Channel home page "Such a Deal" promotional rotation in two (2) separate one-week rotations during each year of the term of the Agreement, once every six (6) months. ii) A link to the Client Site (consistent with the format used on similar links on the same page) will be displayed in the Excite Shopping Channel home page "Shop Here First" promotional rotation in four (4) separate one-week rotations during each year of the term of the Agreement, once every quarter. CONFIDENTIAL iii) A link to the Client Site (consistent with the format used on similar links on the same page) will be displayed on the Excite Shopping Channel home page under the department listings, subject to the following conditions: A) Client is allocated eight (8) separate one-week link displays in each year of the term of the Agreement. Only one (1) link to the Client Site may be displayed on the Excite Shopping Channel home page under the department listings at any one time. Links to the Client Site may not appear under the Auctions, Books or Gourmet & Groceries department listings and may not appear in more than four (4) different department listings during each year of the term of the Agreement. B) The display of all links on the Excite Shopping Channel home page under the department listings is subject to availability at the time. iv) A link to the Client Site (consistent with the format used on similar links on the same page) will be displayed on the front pages of the following departments of the Excite Shopping Channel subject to the following conditions: A) A link to the Client Site will be displayed on the front page of the Department Stores & Malls department of the Excite Shopping Channel for the term of the Agreement. B) A link to the Client Site will be displayed on the front page of one other department of the Excite Shopping Channel of Client's choice for the term of the Agreement, other than the Auctions, Books or Gourmet & Groceries departments of the Excite Shopping Channel. C) Client is allocated twelve (12) months of link display in three (3) separate four-month blocks on the front page of departments of the Excite Shopping Channel other than the Auctions, Books, Department Stores & Malls or Gourmet & Groceries departments of the Excite Shopping Channel in each year of the term of the Agreement. This allocation of links may not be used in more than one (1) department at any one time. 2 CONFIDENTIAL v) A link to the Client Site (consistent with the format used on similar links on the same page) will be displayed in the "Shop Here First" promotional rotation on the front pages of the following departments of the Excite Shopping Channel subject to the following conditions: A) Client is allocated four (4) separate four-week link displays in the "Shop Here First" promotional rotation on the front page of departments of the Excite Shopping Channel other than the Auctions, Books
"""

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

assistant: 31st day of March, 1998