For a concise and readable summary of how fats are constructed, what this
N6/Omega 6, N3/Omega 3, double-bond, cis and trans fat stuff is all about,
see the following message from Dr. Ed Blonz from another mailing list I run:
http://maelstrom.stjohns.edu/CGI/wa.exe?A2=ind9712&L=lowcarb&O=A&P=6624