Is the OGL 1.0 Open Source?

The OGL was intended to be open source. The designer said it was open source. And in open source, you can't change stuff. Or if you do, later people can come along and go, okay, well, I don't like those new changes. I'm going to go with the old one. This is the 2000 does not say that. It says you may use any authorized version of this license to copy, modify, and distribute any open game content originally distributed under any version of this licence. And that's a very different set from what I just read.