[whatwg] <INCLUDE> and links with @rel=embed

[Bjartur Thorlacius]

>> An UA can support the scheme used without supporting the <source>
>> element. If <A> was used, they just had to support <A> and the scheme.
>
> It's still not clear to me what problem this would solve. I see what it
> would do, but why would we want that?
>
Backwards-compat. It's so UAs that don't support <source> can still
grasp some semantical information from the element.