The best Google hit I found for "JQL" was this blog post: Search JIRA like a boss with JQL
But following the highly recommended favorite link there, is completely misleading (not my sense of humor).
In all of the split spaces (what the heck...) I don't have a good hit with the term "JQL" anymore, besides the fact, that the titles of those three new clouds don't tell me at all, what to expect there. "Core" is bullshit and depends highly on the target group which claims for itself what's core from its very specific perspective.
For me as a stupid user it is essential not to make choices first, if I want to learn something new. I request to be guided adequately! But this went totally wrong and I'm really pissed.