Hello again, Doug:
The following is a link to a page which has Sir Crispin Agnew's article about the explanation of the word "sept". The word "sept" seems to be a difficult concept for many of us, especially being raised in 20th century US. :-)http://www.mactamhais.liquidweb.com/names1.htm
When trying to determine which Clan you wish to be a part of, it is very important that you understand the word "sept" and that you know the genealogy of your "own" family.
As Sir Crispin Agnew says in his article: "The difference between clans, families and septs is the source of many questions as is the question phrased in one way or another, which asks, "to which clan do I belong". There are many definitions of clans and families as there are people, but this article will try to indicate how these matters are viewed in the Lyon Court."
I recommend that you read this article and think about it in order to get a thorough understanding of "sept". :-)
Clan MacTavish Genealogist