How can two different descriptions of nature both be right?

Two descriptions are both right when a permitted translation turns one into the other everywhere both describers looked. On opposite sides of a Barcelona street, a delivery van hides a food truck from Bob, so he reports none and Alice reports one. Both are accurate, because only what both saw can be held against them. On that shared part, Alice has the van on her left and Bob on his right, and swapping left and right turns her account into his, the way a clock treats 3 and 15 as the same hour. If she puts the van two car-lengths from the corner and he puts it four, no relabeling explains the gap, and a record has to change. Translations around a closed loop must also return to the start, or a round trip would make something from nothing.