The joint agreement was originally an initiative by Germany, France, Italy, the United Kingdom, and Spain. Roughly 50 early-adopter countries and territories decided to take part, while other countries have indicated their willingness to join.
该联合协议最初由德国、法国、意大利、英国和西班牙发起。大约50个早期采用的国家和地区决定参与其中，其他国家也表示愿意加入。