Thing is that I personally believe that we should be referring to primary and secondary information, not primary and secondary sources. I believe that to be true not because ESM has a system doing that, but because I spent 30y analysing stuff in IT and when I analyse the contents of a gravestone that mentions (directly or indirectly) both death and birth data, it stands out to me that the birth and death information have different degrees of primacy / secondariness(?)
So that's pretty much something that I believe for myself, though I probably didn't develop those ideas directly and equally wouldn't expect everyone else to follow my phrasing - though I would hope that others at least think a bit along the same lines, even if their terms are different.
There are many different techniques - but the issues tend to be very much the same.
