I'm currently trying the Twitter Card Validator for my website.
I did not set twitter:domain, because the help text shows
RESTRICTED - twitter:domain will be automatically generated from your card's URL.
Not required
But I've just wondered if I should set it anyway.
What would be the effect when I set twitter:domain? To which value should I set it? Should I set it at all?
(I guess martin-thoma.com, but it might also be http://martin-thoma.com or martin-thoma.com/.)
Answers that don't cite a reliable source are note acceptable!