It's not. I means that there is a checked version and that checked version has a lower version number than the current version number of that page.
That is, the page had been reviewed in the past, and now is not, since a new, unreviewed version has been saved?
With the possible
side effect that some readers may still see the latest reviewed version of the page, depending on reader and page settings.
Okay, that makes some sense now. Once I have found out what "tagged" means here, I can find a translation, too. Thank you, Siebrand!
In "reviewed pages having...", the "reviewed pages" bit means the pages *whose edits are subject to* the process of revision under Flagged Revs. It does not mean that the pages have/have not been reviewed. I translated this bit as "the pages that are subject to revision" throughout Flagged Revs.
Some readers still seeing the latest reviewed version of the page is not a side effect: it's the purpose of Flagged Revs. Revisions to the page only become generally viewable after revision and approval, or at least the reader knows that the latest revisions have not yet been reviewed.
/me writing of "side effect" above was an obvious misnomer (per false friend), sorry, I corrected that.
"reviewed pages" meaning the pages *whose edits are subject to* the process of revision -- That is of course quite something else than I understood and translated up to now. I used "pages that have (already) been rewied" everywhere as far as I can remember. These meanings have to be documented in in the message documentation, and the corresponding messages fuzzied, else we can guarantee for lots of misunderstandings being translated to something rather undesirable, can we not?
Well, I think you'll find that some people have given up on this extension.
One reason for that is that the developer(s) document nothing; so they don't seem to be interested in correct translations (so my statement above is my personal interpretation of things -- you'll have to evaluate their accuracy).
Another is that some of the key terms in this extension just get changed once in a while: so, if you start a terminology list, as I did, be prepared to keep changing it.
Another is that when you do a formal "review" you're doing a "revision". If you then mix into this the term "revision" as in page history, things can get confusing. In some languages it's a pretty acute problem: for example, I had to go through all the individual messages and do a strict separation of both uses.
All of this work is wasted when someone else comes in and starts translating unawares. So, to keep it right, you'll have to police it. Then we have the problem that once in a while messages come in already "translated" (god knows from where). These get inserted without fuzzying. I haven't checked if that has happened with messages of this extension.
So, good luck keeping that right. Mind you, the extension hasn't been changed for some time now, so it may be stable enough now to justify the effort. The only place where I know it is used is at mediawiki.org.
I don't think the developer(s) are intentionally making it hard for us. They just need to be told how to do it in a way that is suitable for us, if necessary multiple times.