That line describes an automated way for advanced sellers to track where their FBA stock is stored and for how long. By querying the inventory summaries endpoint at the fulfillment‑center level, you get each FC’s code and unit counts.
If you log this daily, you can spot when inventory has sat 30+ days in “attribution” states and treat that as a potential nexus trigger, helping you decide when you must register and start filing in those states.
