4.1 and 4.2

4.1  The Indexed Element of the Unitary Charge in respect of each Contract Year from the Services Availability Date is subject to increases for indexation which shall be determined in accordance with the following formula;

Where:

IEy is the Indexed Element of the Annual Unitary Charge

ay is the value of RPIx for the February twelve (12) months prior to that used in the calculation of 'a' (save in the case of the first Indexation Review Date when it shall be the value of RPIx for February immediately preceding the Indexation Base Month);

b is the value of the RPIx for the month of February immediately preceding the relevant Review Date.

4.2  Indexation shall only be applied once to the UCn during any Contract Year from the Services Availability Date.