Ross,
The illusive, poorly documented and hardly ever used automenu.
Automenu is a method for making specials or price changes. You could in theory have all submenu item assignments done with the feature but I can't think of why you would want to. Automenu overwrites an existing submenu that is flagged to allow automenu overwrite and is fired in events. The items assigned to an automenu are sorted by the priority assignment and then alphabetically by short name if more than 1 item is assigned the same priority in automenu. The pricing for an automenu item is assigned with fixed item pricing. It is really limiting since an item can only be assigned once in fixed item pricing.
The only time I ever use automenu is if a restaurant has daily specials that are the same every week where I do all of their menu management. In this case you would create one submenu for specials the create an automenu for each day with that days items assigned. Then have an event each day firing the automenu. Since they are fired in events you could have many different specials at different times of day.
I have had so many issues training clients as well as technicians on automenus I pretty much stopped using the feature and often disable it in all back of house security levels except my own.
Cheers