Look, I come from the hardware part of the industry and have never seen anyone talk about "master records" in software but always about master devices controlling slave devices. I'll give you that, apparently "master records" are a thing (although I'm curious in what part of the industry). At the same time, it seems so niche and weird to me that there's no point for me to use it. I'll stick with main because it just makes more sense and seems a lot more intuitive to people than to think about master records and what not. You do you, I personally absolutely do not care at all what you go with in your projects.