valuation of variations meaning in English

更改工程量的估价；更改工程量的估值
更改工程量的估值

Valuation of variations
更改工程量的估价
Effect shall be given to the measurement and valuation of variations under sub - clause ( c ) of this clause in interim certificates and by adjustment , if required , of the contract sum project schedule
依照期中付款证书本条（ c ）款规定，并视需要调整合同总价工程进度表，变更工程的测量与估价即生效。
Effect shall be given to the measurement and valuation of variations under sub - clause ( c ) of this clause in interim certificates and by adjustment , if required , of the contract sum project schedule
我的翻译是:应在中期付款证书中通过（如需要时）对合同总价项目进度的调整使根据本款（ c ）条规定进行的变更的测量与估价生效