This excerpt taken from the ROST DEF 14A filed Apr 14, 2008.
Other Award Limits. To enable compensation in connection with certain types of awards to qualify as performance-based within the meaning of Section 162(m) of the Code, the 2008 Plan establishes a limit on the maximum aggregate number of shares or dollar value for which any such award may be granted to an employee in any fiscal year, as follows:
A participant may receive only one performance share or performance unit award with respect to any performance period. To comply with applicable tax rules, the 2008 Plan also limits to 6,000,000 the number of shares that may be issued upon the exercise of incentive stock options granted under the 2008 Plan.