The PIV online uses many symbols that can sometimes be deduced—but not always.
For instance, if you look up mortiĝi, you get:
You can hover over “evi” to discover it means evitinda (avoidable), and the blue-on-green superscript “Z” means the quote is from Zamenhof, but what does the asterisk mean? (In linguistics, a prefix asterisk means “wrong”, and that might make sense here since mortiĝi is “avoidable”.)
Then a symbol like ☞ obviously means “see also”…. The cross in the entry for mortinda is telling you that “mortal sin” is a Catholic usage. Or… maybe it means a Christian usage—or maybe, just “religious”? How can one know?
Other symbols such as ⚥ are, like the cross, understandable in context, but for a reference work, it would be nice to know their “official” meanings.
Is there a “cheat sheet” somewhere? I imagine a printed PIV would have this, but I don’t have one handy.
(Note: an earlier version of this question said I also would like a key to abbreviations in the PIV, but that, it was suggested, made this question a duplicate of another question. Although that answer is in Spanish, so I’m not quite certain it’s a real duplicate in the useful sense, it’s not my place to say—so I’ve removed references to abbreviations. There were comments and answers added that only addressed that part of the question, so you may want to take that into account in reading seemingly-unresponsive comments/answers.)