This paper was addressed a few months ago in Ancestry or Rootsweb.com's Daily Newsletter. Apparently, another experienced genealogist did a research on these same census records and proved that the original author had mis-interpreted the meanings of the lines and marks made by the copies when they were tabulated by the Federal clerks. There was a long write-up about it explaining the exact details of the process, and it was very informatory. It turns out, all of "FWM" was totally incorrect. The original author of the Free White Mulattoes theory removed his work from the internet as a result of these findings. I am going to try to find the Newsletter Issue at Ancestry or Rootsweb, and post it if I can.