That is undoubtedly a unique discovery. Initially, I would assume that it is either an experimental feature or a bespoke server-side chat script rather than something meant for standard gaming.
The item ID answer raises the question of whether the NPCs are connected to a database lookup and whether ...

That is undoubtedly a unique discovery. Initially, I would assume that it is either an experimental feature or a bespoke server-side chat script rather than something meant for standard gaming.