This excerpt taken from the XOM 10-Q filed May 5, 2009.
Restrictions on Transfer; Forfeiture
Unless the Board specifies otherwise in an award, the restricted period for an award under this Plan will commence on the date the award is granted and will expire on the earliest to occur of the following:
the participant leaves the Board after reaching retirement age;
the participant leaves the Board before reaching retirement age and the Board, with the participant abstaining, votes to lift the restrictions on the participant's awards; or
the participant dies.
During the restricted period, awards may not be sold, assigned, transferred, pledged, or otherwise disposed of or encumbered. The designation of a beneficiary pursuant to Section XII will not be considered a disposition or encumbrance for this purpose.
If the participant ceases to be a member of the Board and the restricted period for the participant's awards does not expire as provided in paragraph (1) of this Section, all the participant's awards under this Plan will be forfeited and all right, title, and interest of the participant to receive any shares or amounts in connection with such awards will terminate without further obligation on the part of the Corporation.