Alex made Quest work with XML. He needed a file extension which could be set up to be associated with Quest, though, and he couldn't really do that with the XML file extension, so he decided on changing the XML to Alex's Specification Language. BUT, Photoshop uses ASL, so he just tacked on an X and rolled with it.
Are you sure? I think the previous version of Quest (1 to 4 in fact) used ASL. The X was added for XML, I guess. It is possible the A stands for Axe. Some clues on this very old page here:
I recently found this stuff:
Wow, that's great material! Perhaps there should be a "History of Quest" link on the home page? ...updated as developments occur?
...my suggestion was in connection with the blog material? ...the video is perhaps the basis of a separate thread...