[ttml1] Pull Request: Clarified application of tts:visibility to child elements

palemieux has just submitted a new pull request for https://github.com/w3c/ttml1:

== Clarified application of tts:visibility to child elements ==
Closes #207

Prose copied from [TTML2](https://www.w3.org/TR/ttml2/#style-attribute-visibility)

See https://github.com/w3c/ttml1/pull/270

Received on Thursday, 30 November 2017 01:05:38 UTC