That's correct so when pursuing a green card while in TN status, the applicant should only travel internationally after commencing the green card process on an advance parole travel document (not on a TN) or get his or her green card through a process abroad, called immigrant visa processing. An applicant for a green card in TN status should never seek admission in TN status if he or she is the beneficiary of a pending or approved I-140 petition unless he or she is immigrant visa processing and only then after consulting with an immigration attorney to understand the issues, process, and risks of doing so.