（a）by the contractor to the engineer of his intention to claim extra payment or a varied rate
or price，or
（b）by the engineer to the contractor of his intention to vary a rate or price．
除非在命令作出之後，如是額外或增加工程，則在工程動工前或之後儘快以書面形式：
a)由承包人通知工程師他要求額外支付或更改價格，
b)或由工程師通知承包人他打算改變價格，
否則不得按本條第1款增加或減少工程量，或按本條第2款變動價格。
（3）if，on certified completion of the whole of the works it shall be found that a reduction or increase greater than per cent of the sum named in the letter of acceptance，excluding allfixed sums，provisional sums and allowance for day works，if any，results from：
52．3竣工驗證時，如發現增減工程的費用超過驗收證書所註明數額的_______％，除去所有的規定費用、臨時費用和零工補貼外，如有任何是因：
（a) the aggregate effect of all variation orders，and
變動命令累計所致，以及因
（b）all adjustments upon measurement of the estimated quantities set out in the bill of quantities，excluding all provisional sums，day works and adjustments of price made under clause 70（1）hereof，
修正建築工程清單所列的估算工程量所致，所有臨時費用、零工補貼和本契約第70條第1款規定的價格調整除外，
but not from any other cause，the amount of the contract price shall be adjusted by such sum as may be agreed between the contractor and the engineer or，failing agreement，fixed by the engineer having regard to all material and relevant factors，including the contractor's site and general overhead costs of the contract．
若非其他原因，契約價格應由承包人和工程師協商予以調整，或，如協商不果，則由工程師在考慮所有材料及相關的，包括承包人的場地及契約的一般間接費用在內的因素的基礎上予以決定。
（4）the engineer may，if，in his opinion it is necessary or desirable，order in writing that
any additional or substituted work shall be executed on a day-work basis．the contractor shall
then be paid for such work under the conditions set out in the day-work schedule included in the
contract and at the rates and prices affixed thereto by him in his tender．
52．4如工程師認為有必要，可書面命令將增加或替換的工程按零工計價。此種工程承包人所得報酬應根據契約中的零工細目表的條件，按其標書中所附的價格予以支付。