If you want to write where only select participants can read a topic, there are always private messages on whichever site you're on! :) Otherwise, this feature has the potential to be misused, such as excluding Prefects and other members of staff from seeing topics, which means they can't keep an eye on things.
Ideas
If you want to write where only select participants can read a topic, there are always private messages on whichever site you're on! :) Otherwise, this feature has the potential to be misused, such as excluding Prefects and other members of staff from seeing topics, which means they can't keep an eye on things.