I was looking at the SRD for Spirit of the Century, and I noticed the Wizards of the Coast OGL license at the bottom of the document. I did a bit of digging, and FATE states that it is a derivative of Fudge, and thus must use the OGL (which implies that Fudge is based off of the OGL).
This all seems a bit strange to me, as the OGL is typically applied to d20 systems as far as I am aware.
In what manner does FATE (and Fudge) use the OGL, and what is some of the history behind that?