Misu, you're new to these forums right? :3 From what i've seen in causal at least, people keep most OC talk in OOC, and IC is IC ( I guess people use parenthesis if you needed to really say something, such as apologizing for double posts that this server makes you do sometimes). If someone does something wrong in IC, OOc is the place to yell at them xD politely. It does vary from GM to GM, haha.
EDIT: I think it means you can post four times until everyone else catches up Jk