constraint on one-title-per-lang under Link?

[Joseph Smarr <jsmarr@google.com>]

In reading through the current draft spec, it's not clear to me whether there is an explicit/implied constraint that there can be at most one <Title> element under a <Link> element per value of xml:lang. In other words, I'm hoping that the following is invalid, but I don't see that explicitly stated anywhere:

  <Link rel="http://spec.example.net/photo/1.0" type="image/jpeg"
    href=""http://photos.example.com/gpburdell.jpg">
    <Title xml:lang="en">User Photo</Title>
    <Title xml:lang="en">Second English Title</Title>
  </Link>

I don't see any value in providing multiple titles in the same language, and it's not clear what consumers should do with such a document if they find one (just take the first one and ignore the rest?). If you agree, I'd like to see that explicitly stated in the spec. Any objections?

(The reason I bring this up is that I'd like to specify a JSON representation of XRD, and I'm hoping I can have titles be represented as a map/object where the lang value is the key, e.g. "titles": { "en": "User Photo", "de": "German title", ... }, but I can only do that if the spec guarantees that each language can only appear once in a list of Title elements under a given <Link> element.)

Thanks, js