I have another time worn Fact not theory. My father's family all MacKinnon's had written the name in what we called Scot's shorthand. I wrote my name as my father before me had, with the small c raised above the level with two small lines drawn below, this was done to replace the a. Unfortunately when this was done in birth records etc. when subsequently copied by some other either in long hand or typewritten, the two lines were eliminated. Thus I have a brother whose birth cert. reads Mac while mine and another brother reads as Mc. Hope this helps some.
Pat McKinnon Lockey