Greg Cox wrote:
It should be noted that this subject is not exclusive to Trek or Who. No matter what the franchise, there's always a percentage of fans who really, really want to know if the books are "canon" or not. Did Arnold's insistence on drawing a public line between canon and non-canon material create or/promote this mentality? I'm not sure. Comic book fans tend to be equally obsessed with having to know which old issues are in "continuity" or not, but that probably has more to do with the way comic book companies tend to periodically reboot and revamp their universes . . . .
Well, I don't recall Trek fans talking much about the concept of canon before TNG and Arnold came along. I do think it was Roddenberry and Arnold who generated the notion that canon is something defined by what it excludes.