This excerpt taken from the MOLX 10-K filed Aug 3, 2006.
2. Exercise Periods:
After the Initial Waiting Period, the option is exercisable as follows:
Option shall vest to the maximum extent of 25% of the total number of shares covered by the option during each of the succeeding 4 years, each commencing with the anniversary of the grant. The right to exercise shall be cumulative so that the optionee may exercise in any given year those unexpired shares he could have exercised in a prior year but did not.