A quick definition of ad finem:

Ad finem is a Latin term that means "to the end." It is often used as a citation signal in texts to direct the reader to a specific span of pages. In Roman law, adfinis refers to a relative of one's spouse, while adfinitas refers to the connection between a husband or wife and relatives of his or her spouse. Ad firmam tradidi is a legal term that means "farm let," and ad fundandam jurisdictionem is a historical term that means "for the purpose of founding jurisdiction."