The text of OGL 1.0a does not say that its irrevocable, and that was the big problem. It does say perpetual, but not irrevocable, and that was where the supposed crux of the argument came in. That said, during the OGL debacle, i saw it pointed out that the legal licensing definition of “irrevocable” was decided in court years after the ogl was written. I know the original writers of it had come out and said that they had intended it to be irrevocable, though