Commercial offer of a vendor is valid for certain time period as stipulated in RFP. If validity of the offer expires before approval of Staff Evaluation Report, vendor(s) will be given the option of revising their commercial offer and they can revise their commercial offer at that stage. In all other eventualities, prices quoted by the vendor at RFP stage will remain unchanged irrespective of how much time it takes thereafter for signing of the contract. No escalation is permitted. Vendors are however entitled to exchange rate variation (ERV) on the value of imported content between opening of commercial offer and signing of contract.