https://html.spec.whatwg.org/multipage/input.html#attr-input...
> Authors are encouraged to specify both any MIME types and any corresponding extensions when looking for data in a specific format.
> User agents should prevent the user from selecting files that are not accepted by one (or more) of these tokens.
https://html.spec.whatwg.org/multipage/input.html#attr-input...
> Authors are encouraged to specify both any MIME types and any corresponding extensions when looking for data in a specific format.
> User agents should prevent the user from selecting files that are not accepted by one (or more) of these tokens.