The Engineer may request a proposal, before instructing a Variation, by giving a Notice to the Contractor. Each Provisional Sum shall only be used, in whole or in part, in accordance with the Engineer’s instructions, and the Contract Price shall be adjusted accordingly. Whenever the Contractor considers putting forward a proposal under the Sub-Clause then it must be weighed in the balance as to whether the Contractor while achieving one or more of the benefits offered to the Employer by the proposal deserves adequate compensation. The Engineer shall promptly respond with the particulars requested and the Contractor shall thereafter promptly execute the Variation. The word “Contract” needs to be amended to “Contract Documents”. The amounts payable to the Contractor shall be adjusted for rises or falls in the cost of labour, Goods and other inputs to the Works, by the addition or deduction of the amounts calculated in accordance with the Schedule(s) of cost indexation.