If you live in a Democratic-dominated open primary state, like Massachusetts, you just might be an independent or "unenrolled." It allows you to vote in either primary.
Once upon a time when there were still conservative Democrats running in Massachusetts and Republicans couldn't win anyway, it wasn't a bad deal.
Anyway, my family were "unenrolled" or independent during the Reagan years. We voted for Reagan anyway.
x already knows that stuff.
x has posted on this thread about a RedState story which included this text, "According to the town clerk, Romney became an Republican only on October 19, 1993. The implication is that Romney had either never voted between his registration as a independent in 1979 and 1992 (so his vote in 1992 automatically enrolled him as a Democrat) or that he was a regular Democrat voters in those earlier elections and changed to Republican to run for Senate."
Red State--Mitt Romney: Registered Democrat (also his registration as a independent in 1979)