The FAA registration site has the following on the first page: "Owners must register their UAS by paper if it meets the following guidelines: Your aircraft is used for commercial purposes. Your aircraft is used for other than hobby and recreation. Your aircraft is greater than 55 lbs. You intend to operate your aircraft outside of the United States." It appears they mean meeting any one of the points requires paper registration. Digging deeper into the site, they refer to "if you are going to operate in a country that requires an "N" number." But there is really no clarification anywhere. So - does this mean what the clear language says? But more to the point - Can I take my online registered P3 with me to Mexico next week without violating an FAA regulation (rule, guideline or whatever they're calling them these days)? FYI - Mexico doesn't require a permit for under 2 kilograms.