Never seen 0.5 smerits, the minimum sMerit one can get is 1. So, 1 merit = 0 merits, 2 merits = 1 merit.
It is not a whole number, so it does not show up on the merit page but that is the smerit added to a user when they receive 1 merit.
To understand it better, you have 3 earned merit and 1 smerit. You actually have 1.5 smerits but it does not show up like that until you get another 0.5, when you receive an extra 1 merit. Altogether you now have 4 merits and 2 smerits.
- Jay -