[rst]

So, we have a "standard" which says that both behaviors should be supported, and there should be two different ways to express them, but explicitly declines to say which does what?

I'm genuinely not sure what purpose this particular standard serves, but it looks like it's not allowing people to write portable code...

[anamexis]

I can't imagine the standard does not specify that NULLS DISTINCT should treat nulls as distinct and NULLS NOT DISTINCT should treat nulls as not distinct.

[rst]

Ah. So there are three ways to write it, and explicit ways to call for either behavior. That's sane -- just wasn't what I got from the original writeup.

[mjw1007]

No, it's not as bad as that.

The thing that's implementation defined is what happens if you don't explictly select either option.