Well, I wanted to be sure just since it could theoretically write to it currently.  I think you're right and the code will probably never actually be hit.

With this, I'm hoping we could probably be safe and pretty fast just using DISABLE when the prefixes aren't known.  And that way, we'll see via profiling if some game is setting them any other way (or not, since probably it would not be often even if they did.)

-[Unknown]