This excerpt taken from the BP 20-F filed Jun 30, 2005.
Adjustment of Awards
the event of:
variation in the share capital or reserves of the Company (including, without limitation, by way of capitalisation or rights issue or any consolidation, sub-division
or reduction); or
implementation by the Company of a demerger or the payment by the Company of a super-dividend which would otherwise materially affect the value of an Award, then the terms of
Awards (including, if relevant, the performance conditions applicable thereto) shall be adjusted in such manner as the Committee shall determine in its absolute discretion provided that no adjustment
shall be made pursuant to this rule unless and until the auditors for the time being of the Company (acting as experts not
arbitrators) shall confirm in writing to the Committee that such adjustment is in their opinion fair and reasonable.