(at)thread ping

There's a missing feature with forums and threads. Namely, you can't ping everyone that's already in a thread. You could use (at)everyone or (at)here, but that would pull a lot of people into the thread (depending on server size) and would most likely be an undesirable outcome. 

So, my new suggestion to resolve this missing feature would be a new ping: (at)thread. It would only be available when typing a message inside a thread (whether it be a thread or a forum post). It would ping everyone that was already following a thread. 

A permission node could be made to control who could use this new ping. It could also piggy-back off the existing permission node that controls (at)everyone and (at)here pings.