This excerpt taken from the GWW 10-Q filed Aug 2, 2006.
FMV means a price that is based on the opening, closing, actual, high, low, or average selling prices of a Share reported on the New York Stock Exchange (NYSE) or other established stock exchange (or exchanges) on the applicable date, the preceding trading day, the next succeeding trading day, or an average of trading days, as determined by the Committee in its discretion. Unless the Committee determines otherwise, if the Shares are traded over the counter at the time a determination of its Fair Market Value is required to be made hereunder, its Fair Market Value shall be deemed to be equal to the average between the reported high and low or closing bid and asked prices of a Share on the most recent date on which Shares were publicly traded. In the event Shares are not publicly determined at the time a determination of their value is required to be made hereunder, the determination of their Fair Market Value shall be made by the Committee in such manner as it deems appropriate. Such definition(s) of FMV shall be specified in each Award Agreement and may differ depending on whether FMV is in reference to the grant, exercise, vesting, settlement, or payout of an Award; provided, however, that upon a broker-assisted exercise of an Option, the FMV shall be the price at which the Shares are sold by the broker.