I assume he means if a character gets a level via unnatural means (such as an evented level or experience add-on)... and that wouldn't show...
As far as making a system that shows that... You could always go and have a variable for each player (called Level__) where the underscores are the player ids
Now, Level__ is the name of the event that initialized at the beginning of the game. It is 1 when you start (or whatever the starting level you use is)
Now, you have a parallel process on your maps that can cause these output messages if you level up... Here's what you need:
The index in the game where level information is kept (Idk what it is)
A script that will put this value in a variable.
Now, you just have to check every few seconds if the player's level__ matches the variable gotten from the database. If it does, do nothign, if it doesn't, display a message that __ got a level up~!
as far as the practical and useful way of sayign this, I do not know... I am just good at theoretical...