This excerpt taken from the GM DEF 14A filed Apr 25, 2008.
(a) Deferred Share Units — Represents the unit equivalents of Common Stock for retainer fees deferred into the Director Compensation Plan. For more information about this plan, please refer to “Compensation Plan for Non-Employee Directors” beginning on page 12.
(b) Number of shares that may be acquired through the exercise of stock options within 60 days of February 29, 2008. Directors no longer receive stock options; the last grant was in 2002.
(c) Shares were purchased after February 29, 2008.