complementation agreements meaning in English

补充协议

Nineteen . parties hereto may revise or supplement through negotiation matters not mentioned herein , complementation agreement has same legal efficiency same as the contract
十九本合同未尽事宜，经本合同双方协商一致后，可以签订补充协议，补充协议与本合同具有同等法律效力。
During the construction , if contractor need to increase or decrease or modify the project , which should be granted by client , so that it can execute alteration after getting the complementation agreement in written under both discussion
施工期间承包人如要增减或修改本工程，须征得发包人同意，并由本合同双方协商达成书面补充协议后，方能进行改建。