A particularly large use of Retroactive Continuity (retcon) in which the very nature of an entire
universe, usually a fictional
universe, is changed.
Any revision to a story in which essential details, and established facts are altered in such a way that nothing which has come before is sacred.
Named for the propensity of DC Comics to rewrite the
history of their comic universe every few years to fix mistakes in writing, or to update characters and situations that have been stated in the intervening years.
Johnny originally told me he was at
Greg's house last night, then he hit the DC Reset Button on that and owned up he was out with Sheila.
Han shooting first was
Lucas' worst offense when he hit the DC Reset Button in the original
Star Wars trilogy.