The Schematic after it has been placed in the world in the middle of a ravine. Most of the stone has been replaced with air except an area off to the right which I made a mistake and missed a part of a chunk that needed an Implicit Air Marker.
Working with the ruins before I export them as a schematic. I surround the area with Explicit Air blocks, then put down an Interior Air Marker to mark the inside of the Ruins red. These areas will be marked as air when loaded into the world.