This excerpt taken from the BP 20-F filed Jun 30, 2005.
Specific Provisions relating to Cash Incentive Element
1.1 The Committee may, at its absolute discretion, grant the Cash Incentive Element during any Grant Period.
1.2 The Cash Incentive Element shall be subject to such terms (including performance conditions) as the Committee shall impose at the time of grant. The Committee only intends to grant this Element in special circumstances.
1.3 If an event within rule 7 occurs, any Cash Incentive Element shall be treated in such manner as the Committee specifies at the time of grant or subsequently.