Levin’s U.S. Constitutional NBC Definition: Everyone born anytime anywhere in the world other than those born overseas to two non-U.S. citizen parents.
That seems an accurate understanding of Levin's definition.
Frog's definition: The term NBC as used by the founders cannot be defined by what the founders' DIDN'T say ("if they had intended that, they would have said it") rather, by what they did; i.e., by how they edited the language to exclude any other definition.
1. With reference to the qualifications for president alone, after further consideration they removed from the proposed draft the single word "citizen" and replaced it with the more exacting term NBC. Why would they have done that? Jay's letter provides the reason.
2. After even more consideration, they added by amendment the condition that ANY citizen was qualified for the presidency so long as they were alive at the time of adoption of the Constitution. Obviously, they realized there could be no NBC candidates until sometime after adoption, that only if born after adoption could one qualify as a NBC.
So, regardless of whether there were any other definitions that may seem applicable, we know exactly what the founder's intended and sought to achieve.