This excerpt taken from the HPQ DEF 14A filed Jan 27, 2010.
Vesting Period and Exercise Dates. Options granted under this Plan shall vest and/or be exercisable at such time and in such installments during the period prior to the expiration of the Options term as determined by the Administrator. The Administrator shall have the right to make the timing of the ability to exercise any Option granted under this Plan subject to continued employment, the passage of time and/or such
performance requirements as deemed appropriate by the Administrator. At any time after the grant of an Option, the Administrator may reduce or eliminate any restrictions surrounding any Participants right to exercise all or part of the Option.