In the first place the contractor becomes aware that certain specified stores/materials will be supplied to him by the Department at fixed rates for being used in the works to be undertaken by him for which he has not to pay from his pocket and it is on that footing that he submits his tender quoting a particular figure for the entire work; secondly, such stores/material so supplied by the M.E.S. Department has to be used, fixed or incorporat 3 817 SCI/78 26 ed by the contractor in the works undertaken by him and the surplus, if any, that would remain after the completion of the work is to be returned to the Department; thirdly, since for accounting purposes the initial supply is debited to the contractor at the specified fixed rates, credit for the balance of the stores/materials so returned is also given at the same rates, some adjustment being made in respect of the wear and tear of such stores/material but in regard to the stores/material out of such supply as is actually used, fixed or incorporated in the works, no accounting is done vis a vis the contract payment that is made to the contractor.