Translation metadata for linked content

Hi all,

there is an GitHub issue about translation metadata for linked content, see
https://github.com/whatwg/html/issues/2945
I made people aware of ITS 2.0 locale filter, see
https://github.com/whatwg/html/issues/2945#issuecomment-323930084

I realized in that discussion that in ITS 1.0 or 2.0, we don't have a way
to express that we select linked content. The above issue looks like a use
case for that. What do people think?

Cheers,

Felix