I don't know for wines exactly, but last year/year before, I bought 4 different makes of commercially available mead.
Now it's fair to point out, that they all tasted "cloyingly sweet" - far too sweet for my taste. Inasfaras I deemed them all to be "Dessert" mead.
So what was the numbers? Well, after the taste test, I measured them and all 4 of them came out between 1038 and 1045 for final gravity readings.
Also, I seem to recall reading somewhere, that there is a set of numbers that match the descriptions i.e. dry, medium dry, medium, medium sweet, sweet, etc etc. You'd have to google for it if you want to stick to the numbers rather than back sweetening to taste.
Personally, I do both (with my meads), but more often than not, I just back sweeten to taste......
regards
fatbloke
p.s. Oh and if you put a hydrometer into a measure of "Stones Ginger Wine", I think that you'd be amazed at how much sugar it contains.