The search tips page on Area 51 says, under "Advanced Super Ninja Search Options":
proposals that have been closed closed:1 apples oranges (or not) closed:0 apples oranges
However when I actually search for it,
closed:1 does absolutely nothing useful. None of the proposals returned are closed. I have better luck using
closed:0, but it still returns a mix of all kinds of proposals.
It seems like there's some broken logic somewhere, because if I search using a nonexistent parameter like
apples:1 it doesn't return anything.