Naven
Glossary
Mention
Addressing somebody by name inside a message so they are notified.
The mechanism that makes a busy group survivable: most messages can be muted while the ones addressed to you still arrive. Its failure mode is the everyone-mention, which is why most platforms restrict who may use it.
A good implementation notifies regardless of mute state and says so.
Where Naven stands
Naven supports mentions in groups and channels, with a picker that only offers people who are actually in the conversation.