If a meter device monitored by a node is replaced, the meter reading collected by the node can jump, often going from some large number back down to zero. When calling the /datum/reading endpoint for a time range that includes such a meter "reset" unexpected results are returned, as a simple difference between the first/last readings aren't valid (they refer to different devices).

We need a way to indicate to SolarNetwork that the device associated with a given node+source has been "reset" at a specific point in time. Then the /datum/reading query in the previous example could use that information to break the overall difference into two parts, one for before the "reset" and one for after. The final difference would then be the sum of these two parts.