About Star Wars canon, the official stance is that it all counts to some degree or other, but the truth of the matter is that they're exactly the same as the Trek novels. George Lucas only allowed SW novels in the first place if they followed the precident of Star Trek's!
George Lucas wrote:
I don't read that stuff. I haven't read any of the novels. I don't know anything about that world. That's a different world than my world. But I do try to keep it consistent. The way I do it now is they have a Star Wars Encyclopedia. So if I come up with a name or something else, I look it up and see if it has already been used. When I said [other people] could make their own Star Wars stories, we decided that, like Star Trek , we would have two universes: My universe and then this other one. They try to make their universe as consistent with mine as possible, but obviously they get enthusiastic and want to go off in other directions.
Lenny Nurdbol wrote:
Or because Romulans call themselves Rihannsu instead of Romulans some sort of violation has occurred?!
That's according to Gene Roddenberry himself. The details of why are here: http://www.trekbbs.com/showthread.php?t=208597&page=8
In short, he believed The Romulan Way to be a non-Trek novel which Diane Duane tacked McCoy sub-plot onto in order to make a quick buck.
Many disagree, and the current novelverse Romulans are still heavily based on Duane's Rihannsu.