Those boxed letters/alphabets beside a monster name

Every time i get into combat with any monster and the name turns red, I realise that there would be a boxed alphabet/letter that goes in sequence from a-z.

Let's say the current target I am fighting has a label 'j' next to the name (on the right), then the next target I engage, no matter the type, will have a 'k' on the right of it's name. What exactly is this sequential alphabets for? Besides making alphabet soup out of all the monsters I kill, that is. :p

Thanks!

I think it just is meant to track your aggro with multiple targets. Even if you don't attack, a monster that aggros you gets a letter. It also helps to differentiate between multiple enemies of the same type.

Terrini is correct. It's just to differentiate multiple enemies of the same type. Kinda like old school games used to.

Thanks for the answer!