its for UL508a listed control panels. all motor circuits. in this case for 200 and 250 HP soft starts. I just found the pricing model interesting. another supplier's IT breakers are substantially less for the same frame as a TM breaker. I suppose the marketing geniuses figured out most people can't easily tell what something costs so would assume the IT version was less.
As he said, the pricing you can get is functional, not cost based. It does cost significantly less to manufacture a mag-only breaker compared to a TM breaker. Here is how the pricing works:
IT breakers have only two valid uses; FACTORY built and tested motor starters that are going to be UL listed as complete assemblies after short circuit withstand testing, and replacements as such. So if you are buying a Mag Only breaker from a mfr, and you are NOT one of their partner mfrs using their breakers, then the ONLY reason you can be buying it is because you are REPLACING one that it already installed. Then since they know that you cannot replace one brand with another, they therefore
also know that they can charge you more and get away with it.
It also serves to keep people from buying IT breakers just because they are cheaper and misapplying them. I would see people trying to do that all the time when I worked for Siemens, I would even see it shown in drawings that were stamped by PEs.
Back to the notations, that is an uncommon notation, but I have seen it before and yes it does mean IT (Mag-Only) breakers. The fallacy is, the engineer that put it there was making a pointless notation in that for whatever motor starter they called for, the mfr has NO CHOICE in the sizing of the IT breaker that goes into it, they can ONLY use the size that the starter is specifically UL listed for. So if he picks right, great, but if he picks wrong, he creates a conflict that may need to be addressed via correspondence, a needless waste of everyone's time. I have to deal with this kind of pointless specificity all the time now, bugs the crap out of me.