A friend recently showed me a scan from a Batman comic from Whatever Happened to the Caped Crusader?,
in which Alfred Pennyworth is revealed to be The Joker.
and we ended up discussing whether or not the events shown are considered canon.
The Wikipedia page for the comic states:
The Batman presented in the story is not necessarily the one from current DC Universe continuity but rather an indeterminate amalgamation that pays homage to the entirety of the character's 70-year history.
But the source for this is a news site and nothing authoritative.
Is there an authoritative source stating whether or not Whatever Happened to the Caped Crusader is considered canon?