A structure is considered "under siege" if the owner of the structure has changed in the last 1 hour.
When a structure is under siege, there are a couple of consequences:
- You only receive atium when you break iron blocks if the structure is under siege.
- ALL structures permissions are public - anyone can enter the structure, break blocks, open inventories, etc.
The rationale behind this is simple. When you break into a structure, you need to be able to get your atium back, but the person whose structure you broke into needs to be able to fight back as well.