Theorganisationiscallingformorecountriestosignuptotwoconventionsonstatelessness.这里有个tosignuptotwoconventions小生不知道这个＂signuptosth＂怎么解释,只知道有个＂signupforsth＂

Question

The organisation is calling for more countries to sign up to two conventions on statelessness.
这里有个to sign up to two conventions
小生不知道这个＂sign up to sth＂怎么解释,只知道有个＂sign up for sth＂

Answer 1

sign up to后面跟登记的对象,某组织,某网站,某会议
sign up for后面跟登记是为了什么,要聊天,要开会,要使用邮件