1. Space-time library: The universe is composed of countless hardcover books. Each spine represents a parallel time and space. The thickness of the pages determines the flow rate of time (for example, the pages of the Vatican Secret Code are as thin as cicada wings, 1 second in reality = 1 year in the book)
2. Dark Line Rules: Travelers must abide by the "three no's" iron rule: they cannot carry the original world entity, they cannot change the established binding, and they cannot reveal the existence of the library. Violators will be hunted by the "staple torture officer"
3. Colored ink economy: writing with special ink can be exchanged for space-time currency, and different colors correspond to different functions (crimson ink rewrites fate, indigo ink freezes time, and dry yellow ink corrodes space)
