Or so the story goes.

[keannu]

Is "Or so the story goes." an idiom? What does "or" mean in there?
==========================

One day, to show respect for all that Albert had sacrificed, Albrecht Dürer painstakingly drew his brother's abused hands with palms together and thin fingers stretched skyward. He called it simply 'Hands,' but the world immediately opened its heart to his great masterpiece and renamed his tribute of love 'The Praying Hands.' Or so the story goes. Though this story isn't actually true, people have been telling it for a very long time. The hands were actually a sketch that Dürer did to prepare for a painting. 6It raises the question: What is art about? Is it the work, or what we say and feel about it, that is most important?

 

[Raymott]

It means that the author cannot verify the truth of what he's just written. That is the 'story' - the tradition, the oral account, it's apocryphal. 'Or' means 'At least', as in 'At least that's what they say happened. I can't say whether it's strictly true."
Yes, it's an idiomatic expression.

Another example:
"George cannot have committed the murder, because he was at home watching TV all night. Or so the story goes."

 

[Rover_KE]

For those who demand dictionary definitions confirming what we write, here's one:

or
(conj)

4. (used to correct or rephrase what was previously said): His autobiography, or rather his memoirs, will be published soon.

(Collins)