If that is so, then why does /attack <bt> work when I have taken no actions against the enemy? I was lead to believe that <bt> will target the closest enemy claimed by your party; that is why it doesn't work when the mob is claimed by another party in your alliance. (Red name/Purple name)
I end up using /ignorepet with an attack macro of
/attack <bt> <wait 1>
/attack <stnpc>
That way, if the <bt> macro fails due to alliance claim the <stnpc> pops up and I can still get to the target. But nonetheless it would be nice if there was an easier way to attack alliance claimed mobs without having to resort to using an /assist macro and a caller. Maybe SE could make an /assistalliance command or something of the sort.
This is correct.
<bt> targets the closest monster that is claimed by your party. Remember that any monster is only ever claimed by a single person at any given time - namely, the person who has taken the most recent action on the monster. If someone in your party was the last person to act on the monster, then <bt> will work. If someone in another party was the last person to act on the monster, then <bt> will not work.
I wouldn't mind an <at> tag, but honestly I just manually target things. If you use f1 or f7 to center your reticule on yourself, then you can adjust your camera such that the next thing to be tabbed to is the monster.
Tabbing always selects the next target to the right of your current target based on your current camera view. So, after centering the cursor on your character, you can just adjust your camera such that the monster you want to target is directly to the "right" of your character in your camera view.
If you start to tab with no target, the cursor will default to the direction your character is "facing" and pick the next target to the right of that point.
Fun facts, etc.