 At the time of initial entry, the officer at the port of entry checks that the program start date is at most 30 days ahead, and that the I-20 has a valid travel signature.It is also necessary that, at the time of initial entry, the school the student intends to attend matches the school on the student's visa and the student's I-20, though this is not a requirement in the future.The officer at the port of entry also issues a Form I-94 with expiration date indicated as "D/S" (Duration of Status), which means that the student is in authorized status in the United States until the program end date indicated on the I-20 (and can stay in the United States for up to 60 days after that).