The scope. Timber-to-steel interface carpentry across structural joists, and the ceiling framing hung off the primary structure.
Timber to steel is a detail problem. Where timber meets steel the tolerances of two different trades have to reconcile. Steel is set to fabrication tolerance, timber to carpentry tolerance, and the connection detail has to absorb the difference without transferring load somewhere the engineer did not intend.
Commercial ceiling framing. Ceiling framing on a commercial floorplate carries services, and has to be coordinated with mechanical, electrical and fire before it closes up. Framing it without that coordination means opening it again.