4.1 Subject to paragraphs 1 (Entitlement to make Deductions) and 5 (Repeated Failures) of this Section 3 (Deductions from Monthly Service Payments), and subject also to paragraph 4.2 [and paragraph 4.3] below where applicable, the amount of the Deduction in respect of an Availability Failure is the higher of:
4.1.1 the Minimum Availability Deduction; and
4.1.2 an amount calculated in accordance with the following formula:
D = SUA x SUR x DP
where:
D means the amount (in pounds sterling) of the Deduction in respect of the Availability Failure
4.2 Where the relevant Functional Area is Unavailable but Used the Deduction for the Availability Failure shall be reduced by 50%.
4.3 [If on the relevant day any of the Whole Facilities Unavailability Conditions are met then, for the purpose of the formula in paragraph 4.1 above the SUA will be deemed to be equal to SUF.]