[imsc] Constrain tts:rubyPosition

palemieux has just created a new issue for https://github.com/w3c/imsc:

== Constrain tts:rubyPosition ==
The permitted values of `tts:rubyPosition` need to be constrained per the [requirements](https://w3c.github.io/imsc-vnext-reqs/)

Please view or discuss this issue at https://github.com/w3c/imsc/issues/345 using your GitHub account

Received on Tuesday, 6 March 2018 18:03:28 UTC