The issue or deemed issue of the taking-over certificate signifies the commencement of the defects notification period (DNP), during which the contractor is to complete outstanding items of work and rectify defective or damaged ones so that the works become fully compliant with the contract requirements and may be accepted by the employer. Clause 11.2 of the 2017 Yellow and Silver books provides that work to rectify defects or damage during the DNP is to be executed at the contractor's risk and cost to the extent that the work is attributable to design and non-compliant plant, materials or workmanship. Expiry of the DNP and acceptance of the works by issue of the performance certificate do not signify the end of the contractor's potential liability in respect of any of his obligations. Depending on the governing and/or local law, the contractor might owe duties and have liabilities in addition to those arising under the contract.