[ttml2] Pull Request: Improve constraints on 'tts:rubyPosition' usage (#832).

skynavga has just submitted a new pull request for https://github.com/w3c/ttml2:

== Improve constraints on 'tts:rubyPosition' usage (#832). ==
Closes #832.

See https://github.com/w3c/ttml2/pull/833

Received on Thursday, 14 June 2018 09:55:19 UTC