DOT-5 fluid anyone?

After reading that article by E-booger I thought of something. I used what is called Dot-5 in my car a couple of years ago but I never looked to see if it is actually silicone based. I just thought all Dot-5 was silicone based. He says it don't have to be. Just a higher boiling temp. I do remember that when I used to work on Crown forklifts they all used Dot-5 fluid and it was purple. The Dot-5 I bought from Wal-mart for my car isn't purple. It looks just like regular fluid, clear. Maybe only the purple stuff is silicone based???? I never thought about it at the time. I'm gonna have to see if I still have a bottle of it and read it to see if is actually silicone based.