10In ascertaining for the purposes of this Schedule whether there is any difference between amounts or what that difference is, such adjustments shall be made as may be necessary to take account of periods of different lengths ; and for that purpose a month shall be treated as one-twelfth and a week as one fifty-second of a year.
11Where a registration takes effect from a date earlier than the date of registration, references in this Schedule to the date of registration shall nonetheless be references to the later date.
12Where a rent determined by a rent assessment committee is registered in substitution for a rent determined by the rent officer, the foregoing provisions of this Schedule shall have effect as if only the rent determined by the rent assessment committee had been registered ; but the date of registration shall be deemed for the purpose of this Schedule (but not for the purposes of section 21(2)(b) of the Act of 1971) to be the date on which the rent determined by the rent officer was registered.
13This Schedule shall not apply where a registration is also the first after the completion, during the existence of the regulated tenancy, of works towards the cost of which a grant was payable under Part II of the Act of 1968.