Please answer this: Extract the answer to the question from the following context. Question: What is used as the guide for actions permitted against a receiver? Context: There are many rules to contact in this type of football. First, the only player on the field who may be legally tackled is the player currently in possession of the football (the ball carrier). Second, a receiver, that is to say, an offensive player sent down the field to receive a pass, may not be interfered with (have his motion impeded, be blocked, etc.) unless he is within one yard of the line of scrimmage (instead of 5 yards (4.6 m) in American football). Any player may block another player's passage, so long as he does not hold or trip the player he intends to block. The kicker may not be contacted after the kick but before his kicking leg returns to the ground (this rule is not enforced upon a player who has blocked a kick), and the quarterback, having already thrown the ball, may not be hit or tackled.
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Answer: line of scrimmage

Please answer this: Extract the answer to the question from the following context. Question: What happened in the 15th year of the 21st century? Context: An exception is the United States, where patents filed prior to 8 June 1995 expire 17 years after the publication date of the patent, but application extensions make it possible for a patent to issue much later than normally expected (see submarine patents). The various MP3-related patents expire on dates ranging from 2007 to 2017 in the U.S. Patents filed for anything disclosed in ISO CD 11172 a year or more after its publication are questionable. If only the known MP3 patents filed by December 1992 are considered, then MP3 decoding has been patent-free in the US since 22 September 2015 when U.S. Patent 5,812,672 expired which had a PCT filing in October 1992. If the longest-running patent mentioned in the aforementioned references is taken as a measure, then the MP3 technology will be patent-free in the United States on 30 December 2017 when U.S. Patent 5,703,999, held by the Fraunhofer-Gesellschaft and administered by Technicolor, expires.
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Answer: U.S. Patent 5,812,672 expired

Please answer this: Extract the answer to the question from the following context. Question: What company was ranked 18th for being most innovative? Context: In 2012, Fortune ranked IBM the second largest U.S. firm in terms of number of employees (435,000 worldwide), the fourth largest in terms of market capitalization, the ninth most profitable, and the nineteenth largest firm in terms of revenue. Globally, the company was ranked the 31st largest in terms of revenue by Forbes for 2011. Other rankings for 2011/2012 include 1 company for leaders (Fortune), 1 green company in the United States (Newsweek), 2 best global brand (Interbrand), 2 most respected company (Barron's), 5 most admired company (Fortune), and 18 most innovative company (Fast Company).
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Answer:
IBM