[i18n-activity] Should there be a direction attribute?

aphillips has just created a new issue for 
https://github.com/w3c/i18n-activity:

== Should there be a direction attribute? ==
https://w3c.github.io/ttml2/spec/ttml2.html#metadata-vocabulary-metadata

Throughout TTML (but in this section in particular, which I happen to 
be working on), I see xml:lang represented, but not means of setting 
or managing base direction of natural language text. Should there be 
one?

Please view or discuss this issue at 
https://github.com/w3c/i18n-activity/issues/326 using your GitHub 
account