The rules region above the dungeon surface where inventories lock, class powers fail, and Carl wants answers.
Because the production trailer sits above the surface, the team is in the secondary zone whenever they attend an interview. Carl admits he still does not know what that really means, only that certain dungeon-specific items and protections do not work there, and he is determined to find out more.
The evidence mounts during this visit. Inventories are sealed until Loita opens them for exactly twenty seconds. Katia Grim's doppelganger abilities simply do not function, so she arrives as her human self with a heavy backpack instead of borrowed mass, which Carl finds strange. In the transfer room afterward there are no notifications at all, his UI stays blocked, the Valtay Corporation implant works but returns limited information, he cannot take a screenshot, and he cannot pass through any of the one-way doors.
Manifests as ordinary rooms above the dungeon where the interface goes dark, inventories seal, and powers quietly stop working.
The rules layer governing everything above the dungeon surface, and an open research question for Carl.