I recently noticed the vintage tag. The tag wiki simply specifies, "Used for old vintage LEGO sets and pieces."

How old is old enough for a set or piece to qualify as "vintage"? For example, would Paradisa and Blacktron be considered vintage? 4.5 volt trains? Classic Space (mid-1980's)? Fabuland? The Yellow Castle? Only stuff from before 1970? Only the very early years?

My personal opinion would be that anything before my "dark age" (circa 1995) feels vintage, but I recognize that many people will have a different perspective. Is there anything approaching a consensus on what is and what is not vintage?

I'm not really asking for an exhaustive or scientific answer, and don't need an adjudication on a borderline case. What I want to avoid is, say, tagging a bunch of monorail questions as vintage and then getting stern messages that vintage means pre-1980 and not just discontinued.