I just started rereading a 4koma with 950+ pages/chapters and I noticed that for the first few chapters trying to use the next page for the next chapter sent me to the main page of the manga. When I checked in the chapter number in the reader the first 13 chapters weren't listed and it said I...
The classifications are about how difficult the anomaly is to contain. Basically a safe object is one that does nothing if you leave it alone. You can put it in a box in a warehouse and leave it there even if it's a button that could blow up the world so long as it requires human input to do...