to every extent possible work performed be on the basis of 基于……上recognised employment relationship劳动关系 established through national law and practice. 国家法律和惯例
劳动关系上认为可行的工作都必须要通过国家法律和惯例的制约。
主句因该是extent possible work established through national law and practice
而performed be on the basis of recognised employment relationship是work 的定语
