[ttml1] Pull Request: Handle forward interoperability of attribute extensions in TT NS

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

== Handle forward interoperability of attribute extensions in TT NS ==
Closes #196

See https://github.com/w3c/ttml1/pull/291

Received on Thursday, 14 December 2017 07:10:19 UTC