the rules are clear.
you have go be able to answer a GM at any time should he stop in and say hi.
if you cant or dont, your account is actionable.
PERIOD!
Umm... again, that's not true. No where does it indicate that in the Rules of Conduct, and over the course of the past decade and then some, various members of the development team and community management (when we had those) indicated that as long as your character was not actively engaged in the game, it was not actionable. Not that I would expect GMs today to know anything about that since a majority of them don't actually know anything about UO. It's still a crap shoot as to whether or not you get one who understands the game or not.
6. You may not leave an active character or pet in game while unattended. If your character is performing a skill, text or action, you must be able to respond to a Game Master when one attempts to speak to you.
While I know this will turn into a huge debate onto what that means, the term "active" has, for years now, meant doing something other than standing around. Hence the clarification that if your character is "performing a skill, text or action" -- thus indicating that the GMs can, indeed, see what you are doing -- then you must be able to respond.
If you walk away from your system to go to the bathroom, and your character isn't doing anything other than standing idle, that is not an "active character" standing around "unattended."
And yes, I foresee the counter argument that "active" means "in game" or "logged in," and again, I point out that if that were the case, the rule would not then go on to clarify what it meant by active.