2/ Footnote on the terminology problem.
You've probably heard me say many times that the term "gold OA" original referred to #OpenAccess delivered by #journals, regardless of the journal's business model, as opposed to "green OA", which was delivered by repositories. Hence, gold OA could charge #APCs or not charge APCs. What we now call #DiamondOA was a species of #GoldOA.
But the term has definitely drifted and now most people use it to refer only to APC-based OA and to exclude no-APC or diamond OA. I don't like this drift, and I fought it, in part because it invited misinterpretation of early writings about OA. But I accept the drift because it's a fact of current usage. For more on this drift, see my 2021 Twitter thread.
https://x.com/petersuber/status/1379818546671317002
In its report Springer Nature uses "gold OA" in the new sense, and I use the term in the same sense when discussing the report. Normally, to avoid ambiguity and confusion, I don't use the term at all.
@petersuber this is an 8mportant conversation, not only this idea of gold OA being the elite of OA, but that it implicitly implies Diamond OA as being less worthy, reliable or *worth citing*. Gold OA is now often very high APC, so is a playground for only the most wealthy universities. Diamond OA might therefore be the only path to OA published articles for many academics (including me).