More H7842 (Rainbow) PSU Questions

Tony, et al., On your Rainbow H7842 PSU pinout you list pin #1 as ACOK H. Do you know what monitors that signal? Is it the AC side OK or the DC output OK? I'm guessing that it monitors the AC side to ensure that the incoming "mains" voltage is high enough to not damage the PSU. Is that correct? And nothing monitors the DC output(s) for correctness? ===== For pin #2 you give "IOWR4 L (connected via a jumper)." Does this mean that it is pulled down as "true," and if so, by what? Do you have any idea about whether it can be ignored for use in a DECmate II or if there is a jumper for DECmate use or is it always jumpered? Can you tell me what "IOWR4" means or stands for? ===== I have a question about using an automobile's headlamp for load testing this PSU. Do I need to use an increasingly rare 6V headlamp or can I safely use a "relatively modern" 12V incandescent headlamp? Will the 12V headlamp draw enough to safely load the 5V portion of the PSU? ===== There is another connector coming out of the PSU that just hangs on a plastic clip on the superstructure, presumably for another application that the DECmate II. Since it's probably only one wire, I figured it's some PC-imitation Rainbow-ism [or the Pro 325?] which is never used in the DECmate II, etc. Do you know what this "extra" connector might be for? ===== My next (dumb) question is: "Is the Rainbow PSU a switching PSU?" I assume that it is based on its size & weight, but would like expert opinions to verify this. Thanks, Bob