Who cares about a radar definition of it. I said VISUALLY CLEAR and mentioned hail falling in there. Maybe chasers will take out their GRx and scan the tilts to see it while they are chasing. That'd be exciting.
But yeah, if one wants to be completely anal about it, that's the "real" definition. If you are a chaser out watching things, I guess it's probably enough to know what it visually looks like and that it might not be precip clear(but still called the vault by chasers). Is there some name chasers use for when it's not completely free of precip, but appears so? I bet it's "vault"....but probably should be "visual vault". But I'm sure that's not acceptable enough.