This excerpt taken from the CMCSA 10-K filed Feb 26, 2007.
(a) In General. The Board or the Committee may amend the Plan from time to time in such manner as it may deem advisable. Nevertheless, neither the Board nor the Committee may, without obtaining approval within twelve months before or after such action by such vote of the Sponsors shareholders as may be required by Pennsylvania law for any action requiring shareholder approval, or by a majority of votes cast at a duly held shareholders meeting at which a majority of all voting stock is present and voting on such amendment, either in person or in proxy (but not, in any event, less than the vote required pursuant to Rule 16b-3(b) under the 1934 Act) change the class of individuals eligible to receive an Incentive Stock Option, extend the expiration date of the Plan, decrease the minimum option price of an Incentive Stock Option granted under the Plan or increase the maximum number of shares as to which Options may be granted, except as provided in Paragraph 10 hereof.
(b) Repricing of Options. Notwithstanding any provision in the Plan to the contrary, neither the Board nor the Committee may, without obtaining prior approval by the Sponsors shareholders, reduce the option price of any issued and outstanding Option granted under the Plan at any time during the term of such option (other than by adjustment pursuant to Paragraph 10 relating to Changes in Capitalization). This Paragraph 13(b) may not be repealed, modified or amended without the prior approval of the Sponsors shareholders.