Short answer, surveyors don't use absolute coordinates, only relative ones from locally known points, output as distance and bearing. The actual coordinates "ca

Short answer, surveyors don't use absolute coordinates, only relative ones from locally known points, output as distance and bearing. The actual coordinates "cancel out" of differential GPS, which also makes it much more accurate (and precise) than standalone GPS. Differential GPS (and newer VRS) gets sub-centimeter horizontal accuracy, and has been available for over 20 years. Same goes for North. You try to get it close, but it's the relative angles between bearings that actually matter. So it doesn't matter if magnetic North changes or if there was an error initially measuring it. For legal descriptions of boundary surveys, "what's on the ground" is what controls. Meaning an iron pipe set as a corner doesn't "mark" a property corner, but defines it (unless it's an offset, but it's still the defining feature). The legal description is more a treasure map than some idealized abstract legal "truth". This especially applies to metes and bounds. GPS coordinates are generally not used for boundary surveys, except maybe to drive to the job site. As for neighbors: the only people who can decide where a property boundary falls are the adjoining land owners. It's sort of zen, but the boundary is whatever you agree it is. It fits with the "local first" philosophy. In the absence of agreement, prescriptive acquisition (or judicial delineation) is the general term for when the courts have to become involved in a dispute (because the judge prescribes). "Adverse possession" is a type of positive defense to claim prescriptive acquisition when the party has no good-faith claim to the title. It's what most people think of as squatter's rights. Philosophically, it's not for cleaning up mistakes, but returning idle or abandoned real estate back into active commerce. "Good-faith possession" is if you think you have a legal claim to the property, like if you bought a bad title, or a property owner sold the same lot twice, and has a much lower burden of proof and required period of possession (generally ~30yrs adverse vs ~10yrs good-faith) Judicial delineation is more for bad boundary descriptions or cleaning up mistakes, but there's no need for judges if the neighbors can come to an agreement on their own. They just have to file an amended plat with the conveyances at the courthouse.