Worldline deviation rate.
It is a deviation value calculated by comparing the observation of parallel worldlines, taking the main world one inhabits as the "reference point".
Its significance lies in the ability to quantify the space-time fluctuations of different parallel worldlines on a macro level, allowing one to understand the degree of deviation this worldline has compared to the reference worldline without in-depth knowledge.
When the worldline deviation rate is merely 0.0000001, or when there are more zeros after the decimal point—
Then the corresponding parallel world is often a mirror space-time, where no major changes or turning points in historical progress occur, at most there are some discrepancies in details... For instance, if a major historical event occurs in the real world, it is very likely to happen in such parallel worlds as well.
It's just that there might be some differences in timing, or variations in processes and outcomes, things like that.
