osm.org/browse/way/89902961/history Note that wambag changed the maxspeed (presumably correctly; the city recently took over maintenance from the state), but the source:maxspeed was not touched (and is thus incorrect now). I haven’t gotten a response, but it’s very likely that he was using PL2’s simple mode, which allows you to choose the maxspeed from a dropdown, but has no mention of source:maxspeed.

Possible solution: put a list of all tags at the bottom (possibly ignoring certain ones like TIGER), with some sort of hint showing the correlation between the simple tags up top and the ones at the bottom. This has the beneficial side effect of easing the learning curve.