Certain individuals may be subject in Special Registration, the NSEERS, National Security Entry-Exit Registration System.
You may leave and enter the U.S. only from certain airports. You can find this list at http://www.ice.gov/doclib/pi/specialregistration/WalkawayMaterial.pdf.
If you are now in Special Registration, you MUST check out when you leave the U.S. There will be a special place to do this at the airport when you leave the U.S. DFW is one of the airports designated for Special Registrants to use. Please check in the above site for details.
You must also check in when you reenter the U.S.
The requirement to report to the District Office in 30 days, and annually, has been suspended. You do not need to do this unless there is a special request.
DO NOT forget to check out when you leave the U.S. If you forget, you may not be admitted back into the U.S.