Shadow zone
The shadow zones are regions in answer space that fall between the desired conversion targets for a set's bonus parts. At any given difficulty, there are two shadow zones: the easy-middle shadow zone and the middle-hard shadow zone. For example: if a set is aiming for 90% conversion on easy parts, 50% conversion on middle parts, and 10% conversion on hard parts, a bonus part likely to get 70% conversion is in the easy-middle shadow zone, and a bonus part likely to get 30% conversion is in the middle-hard shadow zone.
The need to avoid topics in the shadow zones can occasionally lead some topics to be underrepresented at a given difficulty level.
Not to be confused with the shadow zone from seismology, the Forbidden Zone from the Quizbowl Resource Center, or the Shadow Realm from Yu-Gi-Oh!.